Anal. Chem. 1981, 53,242R-273R
Food Katherine G. Sloman, Arthur K. Foltz,” and James A. Yeranslan General Foods Technical Center, White Plains, New York 19625
This review covers approximately the period from October 1978, the end of the interval of our last report (28P),to October 1980. We have tried to cite domestic and the more widely circulated foreign journals when work of a similar nature has been reported. The Association of Official Analytical Chemists has issued the thirteenth edition of its book of official methods (3P). The American Public Health Association has published standard methods for the examination of dairy products (ZP). The British Standards Institution has issued a guide for the determination of repeatability and reproducibility of a standard test method (7P).
ADDITIVES Many species considered “additives” by virtue of the known functionality in compounded food systems are “natural” in individual ingredients and might only differ in level. Therefore some overlap of this category to others in a review must be expected; e.g., fats and oils, inorganic, etc. A review dealing with the use of chemical derivative formation as analytical means of determining food additives was published by Conacher et al. (15A). Progress in methodology for additives was reviewed by Ito (30A). Chemiluminescent response of an oil sample was used by Gol’denberg et al. (23A) to relate to antioxidant content. A multispecies antioxidant method for antioxidants using both direct GC injection and extraction before GC was given by Kline et al. (39A). Nakazato et al. (47A) used both TLC and GC for separation of BHA, BHT, and TBHQ in oils partitioning into acetonitrile from hexane solution first. Ito et al. (31A) repcyted a GC detection limit of 0.4 ppm for BHT in butter by their procedure. A micromethod for BHT in owdered milk by Fukushima et al. (19A) made use of GC/Mlafter extraction and cleanup. BHA and BHT along with 10 other preservatives were analyzed by GC after steam distillation into methylene chloride by Isshiki et al. (29A). Meijboom et al. (46A) measured tocotrienols and tocopherols in palm oil by GC after TLC of the unsaponifiables. Page (52A) monitored HPLC effluent at 280 nm in a gradient elution Lichrosorb (3-18 separation of nine antioxidants from fats. King et al. (38A) showed the utility of amperometric detection to the reversed-phase separation of antioxidants and parabens. Hammond (25A) employed crystallization of a methanol-fat mixture as preliminary separation before HPLC antioxidant resolution but had low recovery for BHT. Doeden et al. (16A) chromatographed fats on five microstyragel columns in series to achieve antioxidant separations by GPC. A fluorometric detection system after HPLC determined TBHQ in oils directly injected by Van Niekerk et al. (67A). Toyoda et al. (65A)used back-extraction techniques in their GLC methodology for TBHQ in seafood and oils. Monoglyceride additives in bread were calculated by Venturini et al. (70A)based on fatty acid ratios found in methylene chloride extracts subjected to TLC and then GLC. Boronic acid derivatives of bifunctional compounds were analytically utilized by Singhawangcha et al. (62A) who reported diol analysis in soft drinks. The improved detectability of polyoxyethylene compounds such as emulsifiers was shown after GPC separation by Warner et al. (71A)who used postcolumn ammonium cobaltothiocyanate colored complex formation and flow spectrophotometry. Sen Gupta et al. (61A) conducted a thin-layer separation to detect diethylene glycol monoethyl ether in foods. The dough conditioner sodium palmitoyl-L-ascorbatewas measured in bread by Mauro et al. (45A)utilizing HPLe after a-amylase digestion. Refined oils were analyzed for anionic detergent traces by Rek et al. (57A) using spectrophotometry and methylene blue interaction. Bindler et al. (5A) described exploring the feasibility of flame ionization to detect monoglycerides by passing coated glass rods through the detector after a TLC type separation. Doeden et al. (17A)gave details 242 R
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of their version of a method that directly aspirated fat samples into a N20-CzHZ flame for AA measurement of silicone oils. Wheeler (72A) formed a FeC13 color complex of sodium stearoyl-2-lactylateafter TLC separation and hydroxamic acid reaction in a method for flour blends. Gum thickeners were isolated, hydrolyzed, reacted with trifluoroacetic acid, and profiled by GLC to determine them in skim milk cream and pudding by Glueck et al. (22A). Scherz et al. (59A)reviewed methods for polysaccharide thickeners in foods. Aitzenmueller et al. (1A) reviewed HPLC work on methods for polyols in food. Methods for the determination of preservatives in foods utilizing extraction/distillation followed by spectrophotometric measurements were discussed by Gertz et al. (21A). Hild et al. (26A)gave methods using GC, HPLC, and the TAS method for food Preservatives. A procedure for dried prunes by Stafford et al. (64A) formed the butyl ester of sorbic acid before GLC. Okamoto (51A)formed butyl benzoate directly in soy sauce before extraction/GC. Geahchan et al. (20A) methylated a rennet extract with diazomethane to perform a GLC analysis for benzoic and sorbic acids. UV measurement with a base-line correction technique allowed Goo et al. (24A) to analyze soya sauce for benzoic acid. Bertrand (4A) extracted soda water with ether and did direct GC for sorbic and benzoic acids on an acid column. Rauter et al. (56A)used GC after MIBK extraction of foods. Measurement of these acid preservatives in orange ‘uice by a HPLC method using a p-toluic acid internal standard was shown by Archer (2A). Interfering compounds were removed by “Extrelut” columns before spectrophotometry in the procedure of Schindler et al. (60A) for enzyme preparations. These columns were also found to be advanta eous before isotachophoretic separation of preservatives by kubach et al. (58A). Leuenberger et al. (43A) cleaned up with these columns before HPLC for preservative acids and saccharin in difficult sample types. Neale et al. (48A) reported a direct GC method for benzoic acid in soft drinks, discussin interferences. Mandrou et al. (44A)analyzed fruit juices fortenzoic and sorbic acids by TLC using UV extinction at 227 and 258 nm, respectively. Trifluoroacetyl derivatization steps were employed by Ishikawa et al. (%A) in a scheme to determine p-hydroxybenzoate esters in foods. Laub et al. (42A) found that the TAS method was useful to detect propionic acid and its esters in bread, separating them on a cellulose sheet. Kobori (40A) reported clear reduction waves that were analytically useful for L-ascorbic acid after Norit conversion to dehydroascorbic acid. A thin-layer method was shown by Bunton et al. (10A) to be applicable to meats for added ascorbic and erythorbic acids. Kanmuri (36A)determined glycyrrhizinic acid in pickles and soy sauce with polyamide gel chromatography, diazomethane methylation, and GC. Ogawa et al. (50A) chelated boric acid with 1,3-hexanediol before a curcumin color test in a method for shrimp and prawns. Butanol multiple extraction, polyamide TLC, and various visualization techniques on the plate were utilized by Junge (34A)to detect 5-nitrofurylacrylic acid in red and white wines. Vladimirova (68A) separated this acid from red wines on alumina thin-layer plates after CHC13extraction. A paper chromatographic method was described by acid. Burkhardt (11A)for detection of 3-(5-nitro-2-furyl)acrylic Sweetened milks were analyzed for nitrate by Cantaflora et al. (12A) who modified the xylenol method to avoid hydroxymethyl-2-furaldehyde interference. Cod roe was sub’ected to two diazotization type methods for nitrite content y It0 et al. (32A) to assess the sensitivities. Fiddler et al. (18A) commented on the inadequacy of most clarifying procedures in the nitrate analysis of frankfurters. Choi et al. (14A)found a nitrate-selective electrode suitable for meat analysis making use of Ag precipitation of interferences and differential NOzoxidation to NO3-. Ethylenediaminetetraacetic acid in crab-
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0 1981 American
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FOOD
with liquid smoke flavor with a GC study. Jeuring et al. (33A)
K d h n k w 0. Slonun. Ssnlor Research Specialist. Analytical Chemistry. General Foods W a l Research (B.A.. Smrm Cac @a: M.A. Cohmbia Vnlvarlly). has spechiked P, lhe application 01 anaMical vocedures lo foods. She has had wide exwience wlth lha standard memods of t d analyak and vim the probkms encountered In both memod devebpment for spacilic probkm and me naeds of qualW conhoi. Recentiv she has worked on s~ecialme& mi; for the determina'tion of I d addnlves. for other trace compOnenls in foods. and on suiomation of methods applicable lo foods. Mku K. Follr. Senla Raearch Specialist at G e m 1 Fw& Cenbal Ressarch Analytical Laboratory. has a ba&ground 01 past experience as an analytical ''generalist" wncenhaling heam on chrmnaiDgnphb2 app(oaches. Ha now heads a group s p e cializing in new a n a r n l memodakq and soecki rawest analvrer lor research and qla~nyeoniiai applicitions. he expioration and evaluation of new inshumenla1 and computer a~lomation developments are among his recent respM1sibilHies.as well as h a m BMnive and environmental problems. MBmberehlpS include ACS and ASTME-19.
determined uinine in soft drinks as an ion-pair separated by RP-HPL8.
ADULTERATION, CONTAMINATION, DECOMPOSITION The use of radiocarbon counting to assess the purity of
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natural producta was discussed by Noakes et al. (1958),who referred to cinnamic aldehyde from cinnamon and caffeine from coffee and tea. Bricout et al. (218)suggested comparing "C, i3C/12Cratios, and 2H/'H ratio to distinguish between natural and artificial flavors. A glass capillary column coated with carbowax 20M was used by Jurenitsch e t al. (1338) to separate nonylic acid vanillylamide when present as adulterant in Capsicum preparations. Dhingra et al. (528) detected mineral oil in edible oil by TLC. Mineral oil added to black with TLC-UV peppercorns was detected by Chakravorty (308) fluorescence. Blanchard et al. (168)examined margarines by GC for cholesterol content to assess for contamination with fish oil from machinery. Sitosterol was found by Homherg et al. (115RJto indicate the addition of vegetable oil to hutterfat when GC analysis was performed. Finrkc V I R ) chromatographed triglycerides of cocoa butter and chocolate on a glass capillary column to correlate carbon number distribution with purity and origin. Red palm oil was detected by Grover et al. (938) in other vegetable oils through the color shown when lycopene pigment was separated by TLC and visualized. The absorption spectra of rice bran oil and mustard oil were found hy Jha (1298) to be distinctive enough to detect the former in the latter. A separation of sterols and acetate esters on a reversed-phase TLC plate allowed Mathew et al. (1708) to detect vegetable oils in ghee. Gupta et al. (958) found that TLC of an ethanol extract was useful to identify castor oil added to other oils. Honey was examined for adulteration with high fructose corn syrup by first fractionatin polysaccharides and then conducting TLC separations on $em in work by Kushnir (1488). White et al. (3038) reported a collaborative study, one aspect of which was to evaluate the former method and another to evaluate a method for honey adulterant detection based on the isomaltose/ maltose ratio, as published by Doner et al. (598). A spot test to show if honey was adulterated with jaggery was described b Ayyanna et al. ( 3 8 ) based on sulfate detection. Blunt et a? (178) ap lied l3C NMR spectroscopy to identify tutin in toxic honeylew honey. Carbon-13 to -12ratios were used by Donor et al. (608) to determine if pineapple and papaya had been processed with honey. The stable carbon isotope ratios were also found by Carro et al. (268) to provide reliable information whether maple syrup products were adulterated discussed new knowledge with cane or corn syrup. Benk (88) to he considered in judging whether orange juices were adulterated. Richard (2278) characterized citrus juices with respect to 19 components for judging dilution or additions. Benzyl alcohol was separated on a CB 20M packed column in a method to detect it as a lemon oil adulterant by Bradley et al. (208). BiaLIi (118)separated the fatty acid methyl esters and used polyunsaturated acid content to estimate wild yeast in bakers yeast. Milk serum proteins were separated on urea starch el to detect cow milk in buffalo milk by Addeo et al. (ZR).$he presence of 5-vinyloxazolidine-2-thionewas detectable by HPLC in work by Josefsson et al. (1308) and could have indicated rapeseed component addition. Gerhardt et al. (828)reviewed methods to detect hydrolyzed milk proteins in meat. Poli et al. (2148) used a crossover electrophoresis method to detect soy protein in heated meat products, visualizing hands with indirect immunofluorescence. Both routine and HPLC methods were applied by Josephson et al. (1328) to the detection of cheese whey in ice milk with elevated lactose and lactic acid being found as indicators. Taber (2788) reported an improvement of the monomolecular fat film method for estimating yolk in egg albumin. The protein thiol group content of liquid whole eggs was found to correspond to the presence of incubated eggs when Cattaneo et al. (278) measured it. Iijima (123R) found a polysaccharide that he separated by GPC proportional to say protein in meat. The analyses of foods for trace toxins has become a field of specialization all to itself. Stoloff (2698) reviewed mycotoxin methodology over the last 10 years. Horwitz (1168) reviewed sampling methods for trace contaminants in foods, including aflatoxins. Nesheim (1908)reviewed the literature
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J m n A. Vwadan. Senbr Laboratory Mansgat. General Fwds Cenhal Research DepartmSm @.A. cornell UniverrW: M.S. Adelphi Is lhe supervisw of lhe Carpwale Analytical Laboralorias. Ha was
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employed as an analytical chemist by National Dairy Research LaboTaIorks hom 1948 to 1955 before ioining General Fwds. He has held posIlons in both the Ccxwaie and JelM Research Areas. His work expe rience includes analysis of foodstuHs and natural Ihvors and devebpment Of anaW -1 memods and inSrmmentai capabilMeS fa both research and quality conhol. He is an associate releree of lha AssociatiOl of O W cia1 Anatyilcal Chemists and a member of the American Chemical Society and AASD. He serves as a member of lha U.S. delegation of the Codex Alimentarius Cornmilee 01 Analysis and Sampling.
meat and mayonnaise was separated by RP-HPLC of ita copper complex and UV detection by Perfetti et al. (54A). Ng et al. (49A) could measure disodium acid pyrophosphate in french-fried potatoes with paper chromatography, hydrolysis. and molybdate color formation. Carswell (13A) reviewed sulfur dioxide in food methodology. Sulfite in soft drinks was measured by S,emission when sample was injected into H3POI by Bo danski et al. (SA). Van Lierop et al. (66A) gave a procefure for diethyl carbonate in beverages using GC MS of headspace. Carbon dioxide in cheese was measure in a nondispersive IR spectrometer after acid liberation in a paper by Bosset et al. (7A). Methods for the determination of artificial sweeteners in food were reviewed by the International Union of Pure and Applied Chemist7 (27A). Sontag et al. (63A) gave procedures for extraction an differential pulse polarographic measurement of saccharin in beverages. Chlorophenothiazine was employed as color reagent at 500 nm for saccharin analysis by Ramappa et al. (55A) for soft drinks. Saccharin in sweeteners was analyzed by direct HPLC in a method by Palermo et al. (53A) and measured at 280 nm. Saccharin and cyclamate were spectrophotometridy measured in soft drinks by Krueger (41A) after separation of other interfering ingredients. Kibuta (37A) reported a rapid diazomethane methylation before GC saccharin determination. Kacprzak (35A) assayed saccharin sweetener solutions by GC for the impurity tolueneo-sulfonamide. Von Rymon et al. (69A)gave a TLC analysis to detect acesulfam sweetener using polyamide plates. Their enzymic reference method for L-(+)-glutamic acid in meats was published by the British Standards Oranization (SA), as well as one for glucono-6-lactone @A). baltes et al. (3A) showed guaiacol presence in sausages treated
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ANALYTICAL CHEMISTRY. VOL. 53. NO. 5. APRIL 1981
245R
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for aflatoxin analysis in foods and feeds. The use of mass spectrometry in the trace analysis of mycotoxins, polyhalogenated hydrocarbons, and nitrosamines was reviewed by Self (246B). A review of sampling and analysis for aflatoxin residues in meats and eggs was presented by Loetzsch (159B). Methods for aflatoxins B, G, and M were reviewed by Luethy (163B),including collaborative study results. A thin-layer method cited by Gorst-Allman et al. (91B) was capable of detecting 13 different mycotoxins. Gimeno (87B)improved his previous TLC method by using a yellow filter for plate spot detection. The latest modifications of a minicolumn for aflatoxin screening were discussed by Romer et al. (231B). Mueller et al. (183B) removed chloroform and substituted alternate solvents in a TLC method for B1, B2, GI, and G2in foods. These four toxins were studied by Smyth et al. (258B) with respect to their response by differential pulse olarography and the technique found useful for B1. Lee et a f (156B) reported a 1-h separation of 13 mycotoxins by high-performance thin-layer chromatography utilizin multiple developments and solvent systems. Gallagher et af, (77B)showed that a reaction product of ethoxyquin interfered with aflatoxin B1 analysis. Koch et al. (143B) conducted a reversed-phase HPLC separation at 50 “C with detection at 350 nm for the four aflatoxins, detecting down to 5 ng each. Colley et al. (37B) needed to employ a variety of HPLC columns and mobile phases to separate a number of aflatoxins and their metabolites. Davis et al. (45B)gave a confirmatory test for aflatoxin B1, where the sample solution was rechromatographed after reaction. A ra id screening method for aflatoxin in peanuts was describedgy Davis et al. (43B)which examined fluorescence of a reacted sample extract. Knutti et al. (142B)proposed a plan for sampling ground nuts for aflatoxin contamination. Chang et al. (31B) in their evaluation of extraction methods for peanut meal and butter found the CB method to give higher values. Pons (217B) performed a HPLC separation of peanut extracts on a pPorasil column, detecting aflatoxins B1 and B2 by adsorption at 360 nm and GI and Gz by fluorometric emission at above 400 nm. A separation using reversed-phase HPLC was applied to peanut analysis by Hurst et al. (121B)who also used both UV absorption and fluorescent detection. Schweighardt et al. (242B) conducted their aflatoxin separations by HPLC on a Cyano-SIL-X-1column with UV detection. A method for extraction, fractionation on a silica gel column, and TLC analysis for 14 grain mycotoxins was published by Takeda et al. (280B). A minicolumn ste before TLC was found advantageous by Haggblom et al. (968 to remove interferences to B1 analysis in corn silage. Small silica columns were found to cleanup corn extracts with minimal solvent dilution by Thean et al. (283B)who used 5-p silica gel HPLC and a silica-packed flow cell for fluorescence. A collaborative study on detection of aflatoxin in yellow corn with miniscreening columns was described by Shannon et al. (248B) and favored a combination CPC-Holaday column. Randall et al. (224B) combined rapid extraction and minicolumn screening, i.e., Holaday and Velasco techniques, in a grain application. Pons (216B)compared different extraction solvent systems for corn before silica gel HPLC-fluorescence measurement of aflatoxins. Diebold et al. (56B) used a laser excited fluorescence detector on the B2* reaction product produced from B1 on a TLC plate and injected into a HPLC system to achieve freedom from interference. Iodine was used to derivatize aflatoxin in aqueous solution after cleanup with fluorescent detection serving to measure how much was extracted from corn in a procedure by Davis et al. (44B). Nartowicz et.al. (189B) inoculated coffee beans with Aspergillis parasztzcus to investigate aflatoxin susceptability with respect to whether or not caffeine was an inhibition. De Palo et al. (51B) examined 502 arriving green coffee samples and found no aflatoxin, ochratoxin, or sterigmatocystin, except for the latter in one sample of unsalable quality. Ginger root and oleoresin was analyzed by Trucksess et al. (289B) for aflatoxin with a unidimensional TLC sufficing because of cleanup improvements. Nesheim et al. (191B)studied a method on eggs for B1 and recommended its adoption. Modifications made to a previous method of Roberts and co-workers by Patterson et al. (210B) improved its utility as a multimycotoxin procedure. Methods for zearalenone in corn foods consisting of TLC, HPLC, and GC/high-resolution MS were compared by Scott et al. (245B),and the latter method was found most sensitive 244R
ANALYTICAL CHEMISTRY, VOL. 53, NO. 5, APRIL 1981
and specific. Cohen et al. (36B)described their feed method for this toxin that made use of Sephadex LH-20 column fractionation after “Sep Pak” cleanup and before HPLC. Diebold et al. (55B) found that a laser excited fluorescence detector for HPLC could show linearit down to 300 p of zearalenone. Holaday (112B)presenteBa screening metRod for this toxin that used a minicolumn. A method by Malaiyandi et al. (168B)for agricultural products used absorption at 280 nm to detect the reversed-phase C1 column peak. Schweighardt et al. (241B)employed a Cyano-8IL-X-1column in their separation of this toxin extracted from cereals. Ware et al. (299B),after preliminary partitioning, used Spherisorb ODS RP-HPLC and fluorimetric detection at 418 nm in their procedure. Smyth et al. (257B)measured both trans and cis zearalenone isomers by voltammetric detection of a Licrosorb RP-8 column eluent. A thin layer method for sterigmatocystin in moldy food showed good recoveries for Schmidt et al. (240B). Van Egmond et al. (291B)estimated the aforementioned toxin in cheese with an AlCl:, spray reagent and confirmed it by two-dimensional TLC. The occurrence of ochratoxin A was confirmed by Hunt et al. (119B)in pig kidney by derivatizing with BF3-methanol before HPLC on a bonded CZzcolumn. Joseffson et al. (131B) reported determining both ochratoxin A and zearalenone in the same cereal extract, fractionating the two for cleanup and the measuring by HPLC and series UV and fluorescence detectors. Miskovic et al. (176B)found that a thin corn starch layer could separate 12 m cotoxins using different solvent systems but ochratoxin B i d not move at all. Osborne (204B)presented his procedure for ochratoxin A in flour and bread, using series UV and fluorescence detectors for HPLC detection. A method ublished by Schweighardt et al. (243B)for ochratoxin A was lased on HPLC separation and fluorescence detection after cleanup and used CHC13-MeOH initial extraction. Friedli (73B)discussed the use of mass spectrometr with direct sample introduction to measure aflatoxins B G Mi, and Ma. Gasiorowska et al. (79B) favoreb’ a %% soyvent consisting of hexane-petroleum ether-benzeneCHCl acetone-CH3CN and acetic acid to separate M1 from B1 anginterferences from milk powder. Gauch et al. (80B) claimed sensitivity in the low ppb range for their TLC method which used an Extrelut cleanup. Stubblefield (271B)also used a small silica gel column to remove interferences due to milk and cheese before final TLC separation of M1 toxin. Biondi et al. (14B)monitored a HPLC separation of M1 at 365 nm. An on-column extraction for M which passed a milk sample through a Sep-Pak before HPLk-fluorescence was em loyed by Winterlin et al. (306B). Patterson et al. (209Bp used two-dimensional TLC, extending the detection limit of a method published previously for MI in milk. A modification of Lemieszek-Chodorowska’sown method (157B)allowed her to confirm Mi with a third plate development. Beebe et al. (6B) told of extending an aflatoxin HPLC method to M1 detection down to 0.3 ppb. Four methods for Mi in milk were compared by Fukayama et al. (76B)and the one chosen that used small hydrophobic and hydrophilic columns for isolation before TLC. Trucksess et al. (288B)added citric acid to the extraction solvent and other modifications also to make a method for eggs function for M1 in beef liver. A confirmatory test on a thin-layer plate using trifluoroacetic acid after two-dimensional separation was reported by Van Egmond et al. (292B). Collins et al. (38B)used GC MS of multiple ions to measure T-2 toxin from milk as its MS ether after preliminary TLC separation. A review of the composition and methods for determinin trichothecene mycotoxins was presented by E pley (64B). procedure applicable to cereals that used XAIfS-2 and Florisil cleanup before GC of TMS derivatives was published by Kamimura et al. (135B). Kuroda et al. (147B) employed electron capture GC to detect TMS-tricothecenes in their method. Derivatives formed on a TLC plate allowed Takitqi (281B) to measure the spots from 12 tricothecenes colorimetrically. Patulin was determined in apple juice after ethyl acetate extraction and Na2C03 cleanup by Moeller et al. (177B) who did the final separation on an ODS HPLC column with UV detection. Leuenberger et al. (158B)applied fruit juices directly onto an Extrelut column, eluting onto a silica gel column for secondary cleanup before HPLC or TLC. A procedure for patulin by Meyer (175B)gave two reactions on a TLC plate to confirm its identity. Ough (207B)discussed
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the measurement of patiilin in grapes and wines. Fruit juices were assayed for patulin content by Siriwardana et al. (25533) using column fractionation before TLC wilb spot reaction and densitometry at 256 nm. Mass spectrometric monitoring in low multiple ion and hi h single ion resolution modes were compared by Price (219Iy)for patulin detection and the latter found more sensitive. Clheese was analyzed for mycophenolic acid, penicillic acid, patulin, sterigmatocystin, and aflatoxins using selective extraction, column chromatography and TLC by Siriwardana et al. (245B). Reiss (225B) described using a gray scale to estimate mycotoxins on a thin-layer plate by comparison. Stubblefield (272%) discussed thin layer separation and detection characteristics of citrinin. Its determination in corn and barley was the subject of a paper by Marti et al. (169B)using fluorescence HPLC after cleanup. Engel (63B) separated roquefortin and PR toxin by TLC using densitometry at 310 and 275.5 nm, respectively. Scott et al. (244B) reported that PI3 toxin was unstable in blue cheese after a few days. Ware et al. (300B) gave their HPLC procedure for roquefortine iin blue cheese where they used both UV and electrochemical detectors. A thiin-layer method to detect terreic acid was published by Subramanian et al. (273B). Gilbert et al. (86B)made EC GC the measurement means for residues of 3-nitropropionic acid in cheeses after pentafluorobenzyl derivative formation. Xanthomegnin in corn wm separated by HPLC on Porasil with detection at 405 nm by Stack et al. (261B)who confirmed it by TLC. Saxitoxin from shellfish was measured by UV or fluorescence in a chemical Buckley et al. (24B) built an assay by Bates et al. (33). analyzer capable of separating (by HPLC) and monitoring for paralytic shellfish-toxin. Leuthy et al. (164B) ave data and methods for shellfish toxin. Toxins for Aspergiflisfumigatus were separated by silica gel TLC by Debeaupuis et al. (48B). Sporidesmin was determined by HPLC CIS Bondapak with 254 nm detection in the work of Halder et al. (97B). Dickes (54B) was author of a large review covering GC applications in food analysis particularly for additives and contaminants. Hoffmann (1lOB)reviewed the use of radioimmunoassay to detect hormone residues in meat. This technique was used by Butler et al. (25B)to measure cortisol in milk. A collaborative study on a GC method for melengestrol acetate in cattle feed was reported by Davis et al. (47B). Wortberg et al. (308B)used TLC of azo dye reaction products to detect oestrogen compounds in meat. A method that used fluorometry of dansyl derivatives separated by TLC was described by Stan et al. (263B). Guenther (94B) employed enzymic treatment of extracts from liver before TLC, Sephadex LH-20, and gas chromatography to distinguish between a variety of growth hormones. Hohls et al. (211B)could detect trenbolone in meat samples extracts that were partitioned and subjected to TLC. Laitem et al. (150B) discussed the formation of stable derivatives for GC analysis of anabolic residues. Kinyhercz et al. ( I40B)found they could detect stilboestrol eluting from an HPLC separation with cyclic voltammetry. Stan et al. (262B) discussed the use of GC MS to analyze for seven anabolic drugs in meat as their MS ethers. Smets et al. (25615)cleaned up fractions on hydroxypropyl sephadex before TLC of anabolic compounds for meat analyses. A method for trenbolone and testosterone that was based on silica gel HPLC final separation was given by Stan et al. (264B). Verbeke (2933) described a multiresidue procedure for anabolics that used XAD-2, alkaline celite, and alumina column fractionations before two-dimensional TLC. Coumestrol from soybeans and flours could be detected at 343 nm absorption or 410 nm fluorescent emission after C1 reversed-phase HPLC separation by Lookhart et al. (161Bj. A “boar” taint in fat was fourid by Otto et al. (206B)to be caused by androstenone which was determined by GC. The analysis of veterinary drugs that persist in foods was reviewed by Ryan et al. (234B). Chloramphenicol residues in milk were determined by Wal et al. (2968) using a heptafluorobutyryl derivative for EC GC. These authors (297B) also reported a HPLC me hod. Ruessel (233B)analyzed for this drug in meat using HPLC with fluorescence detection. Chicken meat and eggs were analyzed for zoalene by EC GC of heptofluorobutyric esters in a method by Nose et al. (198B). Imanaka et al. (124B)discussed GC analysis for this residue in the same sample types A method for furazolidone in chicken was given by Suzuki et al. (275B) using HPLC and UV detection at 356 nm. Turkey tissue was analyzed for this
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drug by Hoener et al. (109B)on pBondapak CIS, monitor the 365 nm wavelength. Nitrofurazone in milk was detecte by HPLC screening of an ethyl acetate extract in a paper by Vilim et ai. (295B). Karkocha et at. (136B)could find tylosin traces in poultry with two-dimensional TLC. Wooley et al. (307B)screened for sulfadiazine in calf meat and fluids with a thin layer method. Beef tissues were examined for sulfamethazine content by Seymour et al. (247B)using UV-HPLC. Nose et al. (199B) made use of a GC separation to measure sulfanilamide residual in meat. Goodspeed et al. (9OB) described a method to screen for five sulfonamides as phenofluoropropionic derivatives. Swine plasma was assayed for these t e drugs using TLC se aration after releasing bound moitiezy Bevill et al. (1OB). 8harma et al. (249B)examined meat and fluids for tetracycline drugs with a HPLC method. Residues of tetracyclines in milk were found by Rutczynska-Skonieczna (232B) with a TLC method. Mueller et d. (182B) reported a rapid method for chlortetracycline.HC1 based on turbidimetry after an organism was incubated. Tetracycline residues in milk were silylated before GC in the method of Hamann et al. (98B). Billon et al. (12B)employed electrophoresis to detect a variety of antibiotics in milk. Goitrin was detected in milk by HPLC in the method of B e r n et al. (9B). McLeod et al. (172B) found that heptafluorobutyryl derivatization of goitrin was necessary for sensitive GC detection. tranquilizers in meat were detected by using sulfur-photometric GC detection in a method by Laitem et al. (149B). Tway et al. (290B)used GC to measure arprinocid in chicken meat. The analysis of volatile nitrosamines in food was ublished as part of a treatise on environmental carcinogens Ey IARC. (218B). Snider et al. (259B) described an analyzer that photodecomposed volatile nitrosamines and then detected NO2- electrochemically. Hansen (99B) discussed optimizing chemiluminescence detectors for nitrosamine analysis. Fan et al. (67B)reported the formation of an artifact nitrosamine in the GC in‘ection port. Gough et al. (92B) found NN-dimethylbenzylamine was detected as a nitroso compound due to pyrolysis. Webb et al. (301B) claimed superior sensitivity to all current detection practices for N-nitrosodimethylamine by a GC/MS measurement. Hotchkiss et al. (117B)usin low-resolution MS to confirm nitrosamines in foods, recordei full mass scans. A colorimetric method reacting 4-dimethylaminobenzaldehydewith monoalkylhydrazines formed from nitrosamines was published by Ceh et al. (28B). Fish were analyzed by Boll et al. (18B)using N-sensitive GC. Cross et al. (40B) screened by liberating amines from nitrosamines, forming NBD-amines and then TLC/ fluorescence. Havery et al. (102B)ran GC/MS and TEA methods and found good agreement in a meat survey. Volatile nitrosamines in oils and margarine were assessed by Hedler et al. (104B)using FID-GC and TEA methods. Kostyukovskiiet al. (146B)used TLC and fluorescence for their analysis of meat, cheese, and water. Cross et al. (41B)used diazotization-colorimetry to measure bacon fat nitrosamines by NO - release. The IUPAC (126B) published a survey of methods for nonvolatile nitrosamine analysis. A method by Lee et al. (155B) examined fried bacon for 3-hydroxy-N-nitrosopyrrolidineby GC after volatile derivative formation with TEA detection. Baker et al. (4B) analyzed meat for N-nitrosoproline using HPLC before a TEA detection. Fujinaka et al. (75B) considered methylguanidine a likely precursor to nitrosation. The volatile nitrogen bases of beef were studied by Golovnya et al. ( B B )as N-nitrosamine precursors. Chloramine T was detected as a food contaminant by Steverink et al. (267B) by GLC of its hydrolysis product, sulfonamide. Beljaars et al. (7B) separated the roduct y HPLC. The disinfectant Dikonite was detected Ey Sucman et al. (274B)using a paper chromatographic separation. Residual thiourea fungicide in citrus peels was made into a benzoyl derivative before GLC by Toyoda et al. (286B). Hayashi et al. (103B)used HPLC to measure u-phenylphenol in citrus fruits. This residue and biphenyl were both subjected to GC analysis after steam distillation by Pyysalo et al. (221B) in citrus fruits and apples. Isshiki et al. (128B) showed a simultaneous GC separation of both residues in citrus fruits. Kenmotsu et al. (139B)also used GC analysis for these residues. Lord et al. (162B)gave an improved method for GC analysis with a cleanup if more than screening is desired. Davis (46B) analyzed for biphenyl in citrus by GC without ANALYTICAL CHEMISTRY, VOL. 53,
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steam distilling first. Ott (205B)discussed the value of amperometric detection for 2-phenylphenol traces in HPLC separations. Moye et al. (181B)found 1-naphthylacetic acid in citrus products with HPLC-fluorometry. The method of Cochrane et al. (35B)employed different HPLC columns. The fungicide imazalil in citrus was detected at 202 nm by Norman et al. (197B) after reverse-phase HPLC separation. Onada et al. (203B)derivatized methomyl extracted from tea before GC with sulfur detection. Okuno et al. (201B)distilled and derivatized sodium fluoroacetate from grain and meat before EC GC. Anion exchange LC was the separation mode for Newsome (193B)in his method for maleic h drazide in foods. Ethyleneurea was separated as a pentafluorogenzoylderivative by HPLC in work also done by this author (192B). Nandi (188B)analyzed wheat for glucosamine to assess effectiveness of antifungal treatment. Traces of Kepone were detected in seafood by GLC before and after derivatization in a method by Moseman et al. (180B). Molinari et al. (178B)used direct GLC with EC to measure fungicides in grapes and ‘uice. Bayer 73 was determined in fish using EC GC by LuLning et al. (165B). Toyoda et al. (287B) measured CS2 in mushrooms by distillation and GC with sulfur detection. Harke et al. (101B)detected surface active disinfectants in meat by a TLC method. Wells (302B)studied fish for Eulan WA New isomers and metabolites using GC/MS methodology. Chlorocholine chloride in cereals was reported on by Keitel (138B) usin pyrolysis GC and by Puchwein et al. (22OB)who used T L 8 on alumina plates. Satter et al. (239B) analyzed for MCPA and metabolites in foods by EC GC after TLC cleanup and derivatization. A method for copper trichlorophenolate was shown applicable to cottonseed oil by Sheinina (250B) and used TLC. Ramsteiner et al. (223B) monitored at 240 nm during HPLC separation of hydroxy-s-triazine residues extracted from plants. Traces of Mirex were confirmed in fish by capillary GC/MS analysis by Deleon et al. (49B). Pentachlorophenol traces were found in contaminated carrots and potatoes by Bruns et al. (23B) who compared extraction systems before diazoethane reaction and EC GC. Faas et al. (65B)used EC GC and also HPLC with 254-nm detection in analyzing seawater and marine life. Lamparski et al. (151B) reacted their cleaned-up extracts with diazomethane before pentochlorophenol GC analysis but chromatographed dioxins directly. Firestone et al. (72%)analyzed cows milk for PCP, dioxins, hexachlorobenzene, and pentachloroanisole and gave methods. A method sensitive to ppt levels of tetrachlorodioxin was described by Lamparski et al. (152%) using GC/MS final measurement. O’Keefe et al. (2OOB) discussed a cleanup procedure for traces of dioxin in cow fat and milk. Heikes (105B) analyzed peanut butter for pentachloronitrobenzene utilizing derivative formation and GC/MS measurement. Several kinds of marine life were tested for hydrocarbon traces by Chesler et al. (34B) using headspace GC. Saito et al. (236B) used multiple steps including molecular sieve adsorption to separate and estimate n-paraffins in foods. Takeda (279B) reviewed methods to determine petroleum contamination of food. Hollies et al. (113B) studied methods to measure chlorinated lon -chain alkanes. GC techniques allowed Nakamura et al. f187B) to measure S-containing oil compounds and PCBs. Niimi et al. (194B) employed 14C labeled PCBs to study recovery of methods. Szelewski et al. (276B)commented on PCB losses during fish extraction with chromium trioxide. Tessari et al. (282B) gave a method for PCBs and C1 pesticides in human milk. An EG GC procedure for PBB residues that used disposable glassware was described by Willett et al. (304B). Chau et al. (32B)analyzed fish and water for tetraalkyllead residues using atomic absorption as a GC detector, Egry (160B) identified aryl phos hate in fish by P-specific GC. Oils and fats were examine for anionic detergents by Rek et al. (226B)using methylene blue complexation. Methodology for polycyclic aromatic hydrocarbons was reviewed by Howard et al. (118B). Methods for PAHs recommended by the IUPAC were published (125B). Fritz (74B) detailed methodology for examining foods, soil, and water for PAH contamination using TLC separations. Oysters were analyzed for PAH compounds using HPLC separation after silica gel and SEC prior fractionation in work published by Hanus et al. (1OOB). Toussaint et al. (285B)used HPLC as a cleanup before GC analysis of PAHs in alcoholic beverages. PAHs in yeasts grown on n-paraffins were determined by Santoro et al. (238B)using GC on a liquid crystal phase.
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ANALYTICAL CHEMISTRY, VOL. 53, NO. 5, APRIL 1981
Sagredos et al. (235B) described a method using extraction of PAHs from fats and oils as caffeine complexes before cleanup, alumina TLC, and spectrophotometry. Hutt et al. (122B)investigated the possibility that direct drying cereals could cause PAH contamination. Shiraishi et al. (252B) studied the separation of benzo[a]pyrene and benzo[k]fluoranthene and discussed possible misinterpretation of spectra. Methods and investigations were published for benzo[a]pyrene traces in meat products b Binnemann et al. (13B),in yeast and feed by Ishiguro (127BK in liquid araffin b Nakagawa et al. (185B),in activated carbon a d c a r b o n b%ck by Nakajima et al. (186B),in liquid smoke preparations by Radecki et al. (222B), in edible oils by Shiraishi et al. (251B),and from smoked meat for fish by Gertz (83B)who extracted the caffeine complex into a water phase during a cleanup stage. Benzo[k]fluoroanthene levels were reported in various foods by Shiraishi et al. (253B). Total bromide in foods was measured by Kamimura et al. (134B)with a simple color-indicating fluorescein tube which changed color according to level. Methylbromide residues after fumigation were converted to Me1 and GLC measurement performed by Fairall et al. (66B). Birkel et al. (15B) presented a method for 1Q-dioxane residual in polysorbate emulsifiers. Ethylene chlorohydrin in cocoa was measured by Pfeilsticker et al. (213B) by colorimetric development. Traces of ethylene glycol were converted to butaneboronate before GLC analysis by Mutton (184B). Diachenko (53B) detected industrial amines in fish by GC/MS after cleanup. Styrene was extracted from wine and measured by GC by Boidron et al. (19B). Yamamoto et al. (309B) found traces of l,l,l-trichloroethane in encapsulated foods and drugs by headspace GC. Versans et al. (294B)steam distilled vegetables and fruit into hexane to determine ethylene dibromide by EC GC. Orange juice was investigated for chlorinated solvents by Dug0 et al. (62B)who steam distilled into pentane to trap them before EC GC. Landen (153B) analyzed beverages for traces of CC1 by nitrogen sweeping into pentane before EC A method for organic chloride in lipids was GC or GC described y Cunningham et al. (42B)that precipitated AgCl for measurement. Conacher et al. (39B)reported on sample preparation for organic chloride and bromide analysis in lipids by X-ray fluorescence. Heikes et ai. (106B) identified 2chloroethyl esters of fatty acids in spices and foods by GC/MS after ethylene oxide fumigation. These authors (107B)also identified 2-chloroethyl palmitate and -linoleate in French dressin . Majors et al. (167B) employed SEC to determine antioxifiants in oils, DDT in butter, and other traces. Gilbert et al. (84B) used headspace EC GC to determine l,l,l-trichloroethane in foods stored in PVC bottles. Gilbert et al. (85B) also detected vinylidene chloride monomer in foods packaged in films by a similar technique. Figge et al. (69B) discussed test conditions to assess monomer mi ration from rigid PVC to foods. Cheetham et al. (33B)stucfied the prospect of vinyl chloride/safflower oil reactions and found none. Dennison et al. (50B)gave methods to detect vinyl chloride monomer down to 1 PPB in packagin . Brown et al. (22B) separated acrylonitrile monomer by G from food simulatin systems using a N-specific detector. McNeal et al. (173B7 measured this monomer with GC/MS multiple ion monitoring. Di Pasquale et al. (58B)also investigated migration into model food systems from ABS resins, Gawell (81B) analyzed beverages and packaging for acrylonitrile monomer wlth GC/Nspecific detection. Maple syru was assayed for contamination from methyl methacrylate, to uene and styrene b Hollifield et al. (114B)by GC headspace. Kononenko et al. 545B) used polarography to detect a methacrylic acid copolymer in beer. Figge et al. (70B) studied food simulants to find octyltin decomposition products. Kashtock et al. (137B) followed ethylene glycol migration into simulants from PET bottles. Figge et al. (68B) discussed choices of test systems for migration. The detection and measurement of o-toluenesulfonamide in saccharin was published by Koebler (144B)using HPLC. Szokolay (277B)used a Zorbax CN column for this separation of saccharin impurities. Riisom et al. (228B)separated fatty acid mono- and diacylglycerols in emulsifiers. Red No. 2 was analyzed for a- and &naphthylamines by Stavric et al. (266B) using GC/MS. Dieffenbacher et al. (57B)gave a TLC method to detect emulsifiers in fats. Vitamin A esters were analyzed for BHA content by Pellerin et al. (211B)using HPLC.
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Perfetti et al. (212B) measured EDTA in crabmeat and mayonnaise by ion-pair HPLC. Roedel(229B, 230B) showed thin-layer methodology to measure 6,6'-ethylenebis(2,2,4trimethyl)-1,2-dihydroquinoliie in fats, eggs, fish, and poultry. Cerny et al. (29B) assessed caramel for 4-methylimidazole impurity by GC-N-electxochemicaldetectnon. Isothiocyanates from ra eseed meal were analyzed by Makeshwari et al. (1663) using H$LC, Serotonin in foods was detected by the thin-layer technique of Garcia-Moreno et al. (78B). Matsumoto et al. (171B) discussed a scheme to measure alkylureas by EC GC after derivatization. Nicotine in contaminated beverages was se arated and measured by TLC in work by Lee et al. (154B). Ogen et al. (202B) estimated vicine and convicine in faba beans in their TLC technique. Salek (237B)gave a spectrophotometric method for 5-alkylresorcinolsin rye. Toxins from morels were determined by GC by Stijve (268B) after liberation from their glycosides. Strocci et al. (270B) studied a method to measure cardanol in oils from cashews. Thrasher et al. (284B)gave detail3 of a new plate development system to detect urine residues in foods. A spectrophotometric urea measurement was resented by Goo et al. (89B). Stasny et al. (265B)discusse8meihods to detect asbestos in beverages for SEM analysis. Winclhager et al. (30513)determined total solanine in potatoes by colorimetry with paraformaldehyde H3P04. Dufour et al. (6 IB) discussed using the transmission electron microscope for asbestos in wines. Methods for asbestos isolation and identification in foods were given by Albright et al. (2B). The quality of shrimp was correlated to response of an ammonia electrode by Ward et al. (298B)in a storage study. Kim et al. (141B) showed a simple test to detect volatile! pasture flavor such as trimethylamine on color test strips. Ponder (215B)determined indole in shrimp to assess decomposition. Snygg et al. (26QB)used the patterns of headspace volatiles to classify fish as botulinum positive or negative. Partmann et al. (208B) investigated two radiation induced compounds in meat. Mlorel (179B) gave a method to tell if fish are fresh or thawed based on aspartate aminotransferase ratios. Hobson-Frohock (10823)determined trimethylamine in e s by collecting during freeze drying and then analyzing with a N detector. Meyer (174B)assessed fat oxidative by decomposition by simple color tests. Harrell et al. (120B) reviewed the Maillard reaction in foods. Noomen (196B) followed the size of volatile sulfur peaks as a means of assessing stability of roasted coffee.
($8
CARBOHYDRATES Papers on the determination of carbohydrates continue to cover investigations of hoth new and old methods. Both HPLC methods and GC methods continue to be of use for the determination of individual sugars. Official and Tentative Methods of the International Cornmission for Uniform Methods of Sugar Analysis (ICUMSA) have been edited by Schneider (88C), and the Proceedings of the Seventeenth Session of the Commission have been published (45C). A review of the determination of carbohydrates in foods has been published by Lee (60C) Books on Sugar: Science and Technology including analytical methods by Birch et al. (SC) and on Developments in Soft Drinks Technology, edited by Green (35C),have also been published. A fluorometric detection procedure for aldoses and ketoses separated by thinlayer chromatography has been described by Buechele (1112) using no treatment on the plate except heatin Klaus (54C) has described TLC for sugars and glycerol in teverages with fluorescent detection after treatment with lead acetate. The reaction of sugars with vanadium has been used by Haldorsen (37C) to detect sucrose, glucose, and fructose on thin-layer chromato rams, and Lee (59C) et al. have described the TLC assay of tBe sugars of molasses. A simplified method for the analysis of the silyl derivatives of sugar oximes has been used by Demaimay et al. (19C) to analyze the individual sugars in foods. The liquid-phase SILAR-1OC has been recommended by Hirase et al. (40C) for the gas chromatographic analysis of the alditol acetates of sugars. A method for the preparation of trimethylsilyl derivatives of moistened sugars for gas chromatography has been described by Ogawa et al. (78C) which uses high temperature and long reaction times. Gas chromato raphy after invertase hydrolysis has been proposed by Ford hOC) for the detc,srmination of the sugars sucrose, raffinose, and stachyose. Both HPLC and GC have been
applied by Li et al. (61C)to the analysis of sim le carbohydrates in foods and the two methods found to\e useful in combination or singly. Reducing sugars after borate-complex ion-exchange chromatography have been determined automatically by Sinner et al. (94C) using the reaction with the copper complex of 2,2'-bicinchoninate. Cation-exchange separation of monosaccharides has been improved by Nackenhorst et al. (73C)by the use of propanol-water as eluent, and Mopper (71C)proposes the use of 86.7% ethanol for the chromatography of sugars on DA-X8 resin. Preliminary heating with amino compounds has been used by Iijima (44C) to separate sugars by liquid chromatography with spectrophotometric detection. Hara et al. (38C) have separated neutral sugars as lycamines using an amino acid analyzer. Danneberg (16C) as suggested combustion detection after borate sugar chromatography. Many HPLC methods have been reported in the literature. Hurst (43C) has described the application of HPLC to the characterization of individual carbohydrates in foods. Sugar-cane saccharides have been separated by Wong-Chong et al. using HPLC adsorption chromatography with flow pro ramming (108C)and ion-exchange chromatography (1096. Black et al. (9C) have reported that standardization of the individual sugars is required when analyzing soybean sugars by HPLC. Enzymic and HPLC methods for glucose, fructose, and sucrose in onion powders have been studied by Gorin (34C)and the enzyme method gives consistently higher results, possibly due to enzyme action on soluble oligosaccharides. HPLC has been used by Damon et al. (15C) to determine fructose, glucose, and sucrose in molasses using maltose as an internal standard and by Van Olst et al. (8012) to determine glucose, fructose, and mannose in high fructose syrup products. Dunmire et al. (23C) have applied HPLC to the analysis of the sugars in various food products incuding melibiose, raffinose, and stachyose. DeVries et al. (21C) have found the HPLC analytical results on foods are cornparable with those obtained by chemical methods. In-line purification of saccharide mixtures usin mixed bed resins has been used by Fitt (26C)to remove as[ constituents before HPLC analysis of syrups, and Johncock et al. (48C) have suggested rigid control of temperature of detector and eluent to improve the performance of refractive index detectors for sugars in confectionery. Fermentable su ars in wort have been examined by Moll et al. (70C) by H j L C using rhamnose as internal standard. The use of derivatization with p-nitrobenzyloxyamineHC1 before HPLC has been suggested by Lawson et al. (58C) which makes possible the use of UV detection. Anomers of saccharides have been separated by Kahle et al. (49C) using HPLC on silica gel with chemically bonded 3-aminopropyl groups and by Oshima et al. (81C) on macroreticular anion-exchange resin in the sulfate form. Carbohydrates in avocado cultivars have been determined by Shaw et al. (93C) by HPLC including manno-heptulose and perseitol. HPLC has been shown by Davis et al. (18C)to be useful for the separation of glucose, fructose, and disaccharides in sugar syrups and for the separation of glycerol, mannitol, and sorbitol. Dextrose equivalent of starch hydrolysates has been estimated by Kiser et al. (52C) by calculation from the oligosaccharides separated by HPLC. Acetone-acetic acid-water has been suggested by Muller et al. (72C) as an eluent for mono- and oligosaccharide separation by HPLC. Saccharide distributions up to pentasaccharides have been accomplished by Fitt et al. (27C)on 4% cross-linked resin HPLC columns at 80 "C. A collaborative study of HPLC determination of saccharides in corn syrups has been conducted by Engel (24C)and the method found acceptable. An amine modifier has been used by Aitzetmuller et al. (3C)on silica HPLC columns to convert these columns into highly efficient columns for sugar analysis including oligosacchrides and cyclodextrins. HPLC separation of poly-, oligo- and monosaccharideshas been suggested by Noel et al. (75C),using either refractometric detection or postcolumn reaction with tetrazolium blue. Maltooligosaccharides have been separated by Nurok et al. (76C)using HPTLC with continuous development for 85 min. Mono- and disaccharides, sorbitol, and xylitol have been separated by Woidich et al. (107C)by HPLC on a strongly basic anion exchanger or a modified silica gel column. Reverse-phase HPLC has been proposed by Wells et al. ( 1 0 6 0 for the rapid separation of acetylated oligosaccharides, the eluates were monitored with a moving-wire detector. Maltdextrins have been separated by Jenkins (47C)
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by column chromatography on granulated hydroxylapatite. Mixtures of oligo- and monosaccharides have been chromatogra hed by Vratny et al. (104C)on DEAE-Spheron columns ande!t method applied to the analysis of sugar cane and sugar beet molasses. A selective detection of fructose and sucrose has been described by Qureshi et al. (84C) using the orange color obtained by boiling these su ars with sulfuric acid and Dowex 50W-X8 resin impregnatef with l-chloro-2,4-dinitrobenzene. A colorimetric method for reducing sugar has been described by Khattab et al. (51C) which depends on the complex formed between Cu2+and oxaldihydrazide. Another colorimetric method has been described by Soloniewicz et al. (95C) using the reaction of reducing su ar with 1,5-dihydroxy-4,8-dinitroanthraquinone-2,6 disuffonic acid in alkaline medium. Sucrose in musts and wine has been determined by Schneyder (89C)with diphenylamine after removal of interfering monosaccharides. Invert sugar methods have been described by Dobrzycki et al. (22C),one using a copper rea ent and another involving the mixing and heating of sugar and methylene blue streams and noting the length of the resulting colored zone. GLC and Lane-E non procedures for lactose in milk have been compared by dachi et al. ( I C ) ,the results are similar. HPLC has been used by Euber et al. (25C)for the determination of lactose in milk products after deproteinization with trichloracetic acid. Cryometry has been applied by Ramet et al. (85C) to the measurement of the enzymic hydrolysis of lactose, and Zarb et al. (IIOC)have combined cryoscopy with enzyme hydrolysis to measure lactose in milk products. Lactose has been determined in the presence of other reducing substances, in a method of the International Dairy Federation (46C),by the use of enzymes to liberate glucose and enzyme measurement of the glucose. Differential scanning calorimetry has been applied by Ross (87C) to the rapid determination of a- and @-lactosein whey powders. A method for the electrochemical determination of invert sugar has been described by Krause et al. (56C)which is based on the different rates of oxidation of mono- and disaccharides by iodate and the use of a polarograph with a otentiostat. Enzyme sensors for glucose have been constructe by Koyama et al. (55C) using an ultrafiltration electrode and immobilized glucose oxidase and by Thevenot et al. (102C)using a modified gas electrode with a collagen membrane to which glucose oxidase has been covalently bound. Glucose and fructose in honey have been determined by Gonnet (33C) by enzyme procedures. A study of the determination of sugars in ice cream using enzymes by Cantafora et al. (13C)has indicated that the sucrose determination is subject to interferences from other ingredients. Sucrose in sugar-beetshas been determined by Lowman et al. (62C) by nuclear magnetic resonance spectrometry using a paramagnetic relaxation a ent which relaxes the water protons faster than it does t e sucrose protons. Sucrose has been determined by Weise et al. (105C) with the use of invertase, mutarotase, and an immobilized lucose oxidase electrode. Osmotic pressure of glucose syrups !as been described by Kearsley (50C) as a rapid means for the determination of dextrose equivalent of glucose syrups after the preparation of calibration graphs. The use of a closed flow-through system using enzymes and amperometric detection has been shown by Nikolelis (74C) to be useful for repetitive determinations of maltose, sucrose, and lactose. Carbohydrates have been measured by direct-in‘ection enthalpimetry by De Oliveira et al. (20C)based on t e reaction with periodate. The use of galactose-dehydrogenase for the enzymic determination of raffinose has been studied by Hollaus et al. (4IC) and found unsuitable for determination of the absolute raffinose content. Porous lass-bead columns have been prepared by Meuser et al. (688)for the HPLC of high and low molecular weight glucose polymers. An enzymic procedure for the determination of starch in cereal products has been developed by Baur et al. (6C)using a-amylase and glucoamylase. Beutler (7C)has described the enzyme determination of starch in foods with the use of amylo-6,6-glucosidase and hexokinase. Polarimetry with calcium chloride has been found by Kujawski et al. (57C) to be more reproducible than polarimetry with hydrochloric acid when determining starch in high-starch material. Iodometric determination of extractable amylose has been described by McDermott (64C) as a rapid method for the measurement of damaged starch in flour. A reference method for starch in
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ANALYTICAL CHEMISTRY, VOL. 53,
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meat products has been published b the British Standards Institution (IOC). A modified methocrfor microdetermination of hydroxyethyl groups in hydroxyethylated starches has been described by Grigor’yan et al. (36C)by formation of the alkyl iodide and then conversion of the iodide to carbon dioxide and water. Reviews of procedures and problems in the determinations of dietary fiber have been published by Theander et al. (IOIC), by Spiller (97C),by Southgate et al. (96C),by Selvendran et al. (92C),by Asp (5C), and by Schwerdtfeger (91C). Modifications of methods for dietary fiber constituents have been suggested by Fonnesbeck et al. (29C) using preliminary enzyme (pepsin) treatment for cell-wall material, and solubilization of hemicellulose in 4% sulfuric acid. Pepsin-pancreatin pretreatment has been used by Honig et al. (42C) to determine the indigestible content of soybean products and cereal beans. The use of a-amylase has been suggested by McQueen et al. (65C)for the determination of neutral detergent fiber in cereals and vegetables. A series of enzyme treatments has been proposed by Schweizer et al. (9OC)for the determination of dietary fiber and available carbohydrates in cereals, vegetables, and fruits. The analysis and chemical characteristics of water-soluble and water-insoluble dietary fibers have been discussed by Theander (1OOC). Lignin extraction by acetyl bromide has been investigated by Robertson et al. (86C),and only a trace of lignin was found in vegetable fiber. A collaborative study on determination of crude fiber in flour has been conducted by Player et al. (82C),and the method was found repeatable and reproducible. Methods for the identification and characterization of palatinit have been developed by Gau et al. (3IC). Dextran in cane juice has been detected by Geronimos et al. (32C)using viscosity measurement before and after the addition of dextranase. HPLC has been applied by Kitahata et al. (53C)to and y-cyclodextrins in starch the determination of a-, 0-, hydrolyzates. A modified method using amyloglucosidasehas been developed by Menger (66C) for the identification of “dextrins” and soluble dietary fiber in bakery products. 0D-glucans in cereal grains have been analyzed by Prentice et al. (83C)by hydrolysis in buffer with a 0-glucanase enzyme complex. The stopped-flow technique has been applied by Obata et al. (77C)to the determination of triose reductone. Maltooligosylsucrose and other oli osaccharides have been determined by Okada et al. (79C)t y the use of HPLC. A Handbook of Water Soluble Gums and Resins has been edited by Davidson (17C). A rapid method for the determination of methoxy grou s in pectins has been described by Lur’e et al. (63C)which gtermines the methyl alcohol produced by distillation into potassium dichromate. The mhydroxydiphenyl method for pectic substances has been automated by Thibault (103C). Silylation and GLC has been used b Stromeyer et al. (98C)to characterize the monomeric breakd/own products of pectins. The same authors (99C)have analyzed methyl glycosides, formed from pectin preparations, by GLC and mass spectrometry. A scheme for the analysis of polysaccharide gums used as food additives has been proposed by Mergenthaler et al. (67C)by permethylation analysis. Procedures for the analysis of technical sodium carboxymethylcellulosehave been described by Foliforova et al. (28C). “Analytical Methods for Glycerol” has been published by Ashworth et al. (4C). The reactions of molybdate and tungstate with mannitol and sorbitol have been proposed by Mikesova et al. (69C) as the basis for a potentiometric determination of the hexitols. HPLC determination of stevioside and rebaudioside A has been described by Hashimoto (39C), the special resin column also separates glucose and sucrose. Potato glycoalkaloids have been determined colorimetricall by Coxon et al. (14C) using dye-complex formation wit{ bromothymol blue or by GLC and have been separated by Bushway et al. (12C)using HPLC. Saponins have been determined by Aguilar et al. (2C) in quinua by a method based on their hemolytic activity on human erythrocytes. (See also Nitrogen Section for glycoalkaloids.)
COLOR Methods for both natural and artificial colors continue to proliferate in the literature. It has been necessary this year to eliminate some papers which are repetitive or in less easily obtained journals unless of special interest. A handbook of U. S. colorants for foods, drugs, and cosmetics has been
FOOD
published by Marmion (320). The identification of anthocyanins by pyrolysis-mass spectrometry and pyrolysis-gas chromatography has been described by Mueller et al. (360). Cranberry anthocyanins have been separated and identified by Camire et al. (110) using high-pressure liquid chromatography. Grape juice anthocyanins have been analyzed by Ohta et al. using thin-layer chromatography (390)and column chromatography (400). Sugars have been shown by Ohta et al. (380)to increase the tibsorbance of an anthocyanin solution from rape juice. Glucosides and diglucosides of anthocyanic!& from grape juice have been separated by Williams et al. (620) using HPLC. A procedure for the detection of beet pigments and carminic acid in orange juice has been described by fhdrey (30). Citrus carotenoids have been separated by Gross (250) using thinlayer chromatography, and Fiksdahl et al. (160) have studied the separation of carotenoids by HPLC. Calabro et al. (100) have used HPLC to determine a- and @-carotenesin citrus juices. A separation schleme for chlorophyll and carotenoid pigments in capsicum cultivars has been described by Buckle et al. (9D) using column chromatography and thin-layer chromatography. Heme pigments in med, have been determined by Okayamu et al. (410) by spectrophotometry after acetone extraction, and a similar technique using a buffered extraction medium has been described by W arriss (610). Myoglobin derivatives in meat or fish have been analyzed by Wolfe et al. (640) by absorption spectrophotometry, and Wang et al. (600) have used fluorometry for the determination of hemoglobin and myoglobin in fish muscle after conversion of the heme moiety of hemoproteins to the free porphyrin by incubation with oxalic acid. The tannin content of sorghum grain has been determined by Sharp et al. (520) by direct ultraviolet spectrophotometry on a clarified hydrochloric acid-ethanol extract. Modifications to the vanillii reaction as an assay for tannin in sorghum grain have been suggested by Price et al. (430) including control of acid concentration and temperature. A simple method for curcumin in foods has been described by Yamada et al. (650) after ether extraction. Mixtures of turmeric, curcuma lon a Linn, with Curcuma aromatica Salisb have been examined y Raghuveer et al. (440) by TLC and 5% of the latter can be detected in turmeric by thin-layer and gas chromatography. A scheme for the identification of natural coloring matter utilizing extraction and column cleanup has been used by Gherardi et al. (240) to identify betanin in tomato powder. A simple extraction with acetone has been proposed by Adsule et al. (ID)for the estimation of lycopene in tomato. A column-chromatographicteclmique on Sephadex LH-20 has been applied by VanDam (59D) to the separation of colored components of red wines. Another column chromatographic technique described by Siimard et al. (530) uses polyclar AT and silica gel to separate the coloring matter of fruit juices and wines. Methods for the estimation of' colored material in musts and wines have been suggested by Bourzeix ( 8 0 ) using TLC and Polyclar A T removal of the colored substances. A TLC densitometric method for the determination of gallic acid and gallotannins in wine and cider has been described by Dadic et al. (150). Enzymes have been used by Bolex et al. (2'0)for the release of synthetic colors in foods such as kippers and chocolate sponges. Orange GGN has been identified and separated from other dyes by Courcelles et al. (130) by reduction with titanium chloride after spotting for paper chromatography. Thin-layer chromatographyhas been used by Laub et al. (300) to differentiate between Yellow-Orange S and Orange GGN after extraction from the food by the wool fiber method. Water-soluble food dyes have been separated and identified by Lepri et al. (310) by TLC using ion-exehan e and soap thin-layer chromatography; Rf values are tabulateffor 18 dyes. Tartrazine in candies has been determined by Wisker et al. (630) using TLC on silica gel plates and automatic densitometry. An electrophoretic thin-layer technique on Silica gel G has been described by Tewari et al. (560) for the separation and identification of synthetic dyestuffs in li uors and beverages, and gel electrophoresis on polyacrylande gel has been used by Banerjee et al. (40)to detect food colors with a detection limit of about 10 ppm. Trace amounts of some dyes including amaranth have been detected by Himchi et al. (260) by resonance Raman spectrlometry at the ppb level. A method
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for the simultaneous determination of dyes in binary mixtures has been described by Oda et al. (370) by laser-induced photoacoustic spectroscopy; amaranth could be detected at the 1.1nM level. Both HPLC and TLC methods have been used by Martin et al. (330)to determine synthetic acid dyes in alcoholic products after extraction on to wool yarn. Ion chromatography analysis has been applied by Fratz (220) to the analysis of anion residues in various color additives. Ion pair partition HPLC has been used by Aizetmueller et al. (20) to separate the food dyes Orange GGN, Sunset Yellow, and Ponceau 4R in fish using an eluant of water-acetone containing Bu4NC1. High-pressure liquid chromatography has ) the separation of food been applied by Masiala-Tsobo (340to dyes using ion-pair and reversed-phase techniques and by Merle et al. (350)to the separation of Orange GGN and orange S using a similar technique. Other HPLC methods for synthetic food dyes have been described by Chudy et al. (120) using ion-pairs formed with cetrimide, and by Steuerle (550)who uses the technique for enrichment, cleanup, and chromatography. Amberlite XAD-2 has been used by Uematsu et al. (580) as an adsorbent for the isolation of 11 water-soluble food dyes and for TLC of the dyes. Differential pulse polarography of food dyes has been described by Powell (420) for Green S and by Fogg et al. (190, 200) for mixtures of dyes in soft drinks. In a later study by Fogg et al. (210) the effect of tetraphenylphosphonium chloride in shifting the half-wave potentials of some azo coloring matters and other dyes has been discussed, with their implication for polarographic determination of dyes. Dual wavelen th spectrophotometry for quantitative analysis of coal-tar cfye mixtures has been described by Sasaki (460) and applied to coal-tar and xanthene dye mixtures; the method has been applied to binary mixtures of coal tar dyes by Sasaki et al. (470) and by Sasaki to two or three component mixtures, even in turbid solution (480),to liquid food (490), and to solid foods (500). A collaborative study has been reported by Cox (140) on the results of HPLC analysis of the minor components of FD & C Yellow No. 6, and agreement between participating laboratories was good. HPLC has also been used by Jones et al. (280) to separate the major dye and non-dye Components of C. I. Food Brown 1. Naphthylamines in DF & C Red No. 2 have been determined by Stavric et al. (540) using gas-liquid chromatographic-mass spectrometric determinations. Hesperidin in orange juice has been determined by Fisher (170) using HPLC thus shortening analysis time, and Galensa et al. (230) have separated acetates of flavonoids on HPLC using silica gel and four different liquid systems and applied the system to fruit and vegetable extracts. TLC of flavonoids (hesperetin and its glucosides) has been applied by Bessho et al. (50) to the determination of these compounds in foods and Schmid (510) has suggested TLC on S & S Cellulose G1440 for the separation of several flavonoids includin quercitin, rutin, and other flavonol glycosides in fruits. spectrophotometric determination of quercetin in onion with vanadyl ion has been described by Kaushal et al. (290) after extraction and paper and TLC separation. Flavonols in tea have been determined by Hirose et al. (270) using HPLC and UV detection. Methoxylated flavones have been determined by HPLC in citrus juices by Ting et al. (570), in tangerine and orange peels by Bianchini et al. (6D), and in orange juice by Rouseff et al. (450). The AOAC method for yolk color analysis has been evaluated by Fletcher (180) and found adequate only if the egg yolk color comes from a monopigment source.
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ENZYMES Interest in analytical methods for enzyme contents of foods appears to be increasing each year. A rapid nephelometric determination of a-amylase activity in sprouted wheat kernels has been described by Prasad et al., (22E, 23E), and Mathewson et al. (12E)have used Cibacron blue dyed amylase substrate for the determination of a-amylase also in sprouted wheat and sensitivity has been increased. Mathewson et al. (11E)have also described a compact self-contained unit for the assay of a-amylase in cereals. A modified Amylograph test for diastatic activity in flour has been shown by Ranum et al. (24E) to permit distinction between fungal and cereal enzyme sources. Interlaboratory differences in the determination of a-amylase in malt have been traced by Pieper et al. (21E) to the lack of standardization in the commerical ANALYTICAL CHEMISTRY, VOL. 53, NO. 5, APRIL 1981
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soluble starches used; and Seidemann (25E)has proposed both paper chromatographic and microscopic methods of characterizing the starch to be used. A glucose analyzer has been used by Paul (19E) to determine glucoamylase. An automatic programmable viscometer has been suggested by Moll et al. (14E) as a means of determining the endo-P-glucanaseactivity of malt. exo-1,4-P-xylosidaseactivity in rye has been determined by Fretzdorff (5E) using 2-nitrophenyl-P-n-xylopyranoside as substrate. A spin-labeled substrate has been used by Johnston et al. (9E) to assay lysozymes with good sensitivity. A sensitive turbidimetric method for lysozyme in cheese has been described by Hansen et al. (7E), and Tsumuraya et al. ( B E )have described another turbidimetric method which has been applied to foods. Rapid methods for alkaline phosphatase in milk and cream have been collaboratively studied by Murthy et al. (15E) using the Scharer rapid test, as well as methods for differentiating reactivated from residual phosphatase (16E),and these authors have also described (17E) a method for predicting minimum detectable residual phosphatase in high-temperature short-time processed dairy products. Three hydrogen donors have been compared by Marshall et al. (10E) for the determination of peroxidase activity and guaiacol or pyrogallol at higher concentrations than usually recommended have been found suitable. A method for peroxidase activity in cereals has been suggested by Fretzdorff (6E) using ophenylenediamine as H donor. Pol henol oxidases have been separated by Thomas et al. (27E)Ty thin-layer chromatography on Sephadex G-75 Superfine. Proteinase activity has been determined by Holm (8E)by an automated method with a trinitrobenzenesulfonic acid reagent. Standardization of the determination of proteinase activity has been proposed by Behnke et al. (1E)usin rigidly controlled conditions. Studies on rennet analysis inckde the application of chromatography on DEAE-cellulose by Carini et al. (2E),the use of fluorescamine to determine the release of the caseino-macropeptide by Pearce (20E), and the study by Molinari (13E)of milk coagulants by the use of isoelectric focusing. Chymase in rennets has been determined by DiGregorio (4E) by selective adsorption on Sepharose 4B quinonate. DeKoning et al. (3E) have sug ested the use of a synthetic hexapeptide as a substrate for t e determination of chymosin activity. Succinic dehydrogenase has been determined in fish by Parisi et al. (18E)by the reduction of triphenyltetrazolium chloride. Smith et al. (26E) have studied the method for the determination of trypsin inhibitor in foodstuffs and modified the method for interpretation of the data.
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FATS, OILS, AND FATTY ACIDS The crystallization and melting processes of cocoa butter have been studied (14F) by use of pulsed low-resolutionNMR. Use of pulsed NMR has also been applied to the determination of oil in mustard, sunflower, and soybean seeds without prior wei hing and drying of the seeds (104F), and Robertson et al. f85F) have investigated variables affecting the determination of oil in sunflower seed by wide line NMR (a technique under consideration as the official method for the domestic trading of this material). A procedure is described for the complete extraction of lipids from immature soybeans including highly polar glycolipids (80F) which is reported to eliminate artifact formation, recommendations are made (118F)for the extraction of lipids from alimentary pastes, and a modified extraction technique is described for determining avocado oil by refractometry (55F). A rapid, dry column method is given ( 6 5 9 for measurement of the total fat in meat and meat products and use is made of a gallium arsenide infrared emitter to estimate the fat in ground beef (63F). Tanaka et al. (103n.report on a TLC method for determining the molecular species of lipids using a FID detector in situ after separation on a silica gel sintered rod impregnated with 12.5% AgNO, Radwan (82F) couples two-dimensional TLC with GC for the determination of lipid classes and constituent fatty acids, and TLC combined with GLC is also applied to lipid analysis of plant tubers (74F). Tweeten and Wetzel (106F)describe the analysis of fatty acid composition of grahs and feeds by HPLC after formation of the p-bromophenacyl fatty acid esters, conditions for the HPLC separation of fatty acid phenacyl esters by gradient elution are optimized (24F), Parris (78F) reports on the HPLC separation of mono-, dl250R
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and triglycerides by reversed hase HPLC using infrared detection, and Smith et al. (993apply reversed-phase HPLC and nephelometric detection to analysis of nonpolar mixtures at microgram levels. Methods are given for the GC separation and determination of butter triglycerides (112F) and for the extraction and quantification of total lipids in cereal grains and similar materials b GC after formation of the fatty acid methyl esters (FAMEY of the crude li id extracts (67F) Schmid et al. (87Fj apply glass capillary Ge-MS to the analysis of butter triglycerides and show that their interface system (glass) does not reduce resolution. A procedure is described by Aneja et al. (2F) wherein the unsaturated triglycerides in fats are oxidized to a mixture of a-keto1 and dihydroxy compounds, using aqueous alkaline KMn04and a hase transfer catalyst prior to isolation of the fully saturate$ triglycerides by column chromatography and their determination by GC. Bouvron (22F) has applied a GC method to determining the saturated triglycerides of palm oil fractions and Herslof et al. (34F) describe HPLC conditions effecting the complete separation of saturated triglycerides differing by two methylene units. Esterification of fatty acids with 4-nitrobenzylbromide prior to analysis by negative-ion mass spectrometry (35F) produces base peaks due to carboxylate anions providing a large enhancement over what is obtained by other reported techniques and permits detection of the acids in nanogram amounts, and techni ues are given (111F) which employ support coated open t&ular GC/chemical ionization MS with N H , CH,, and He as respective reactant gases to differentiate unsaturated and cyclopropane FAME. Karlin et al. (44F) make use of tetramethylammonium hydroxide to form the methyl esters of fatty acids (free or in glycerides) directly in the injection port of a gas chromatograph, and data are provided on the precision and accuracy of an automated GC analysis system (629 for neutral lipids. The HPLC analysis of triglycerides by chain-length and degree of unsaturation on silica gel columns is presented by Plattner et al. (81F),and the quantitative as ects of reverse-phase HPLC applied to saturated triglycerigs has been studied using refractive index detection (560. Schwartx (89F) describes the use of a Celite-potassium tert-butoxide column to effect the rapid saponification of microgram amounts of lycerides at room temperature, Simpson and Osborne (93fi report on a rapid GC method for estimation of fatty acid levels in vegetable oils, and a GC method is provided (41F) for minimizing losses of short-chain fatty acids by first preparing their propyl esters with trifluoroborane-1-propanolreagent. Bitner et al. (9F) describe an automatic system for transesterifying and analyzing fats and oils by GC and an automated and rapid quantitative analysis of lipids with Chromarods (silica rods coated with sintered silica gel) using an analyzer with a flame ionization detector is also reported (94F). A method is given (97F) which employs argentation HPLC for analysis of trilycerides and permits rapid and quantitative separations to e! effected including positional triglyceride isomers containing one unsaturated and two saturated fatty acids (i-e.,SUS from SSU). Argentation chromatographic methods are presented for the TLC separation of polyunsaturated FAME (92F), for the silver resin separations of saturated, unsaturated, and acetylenic fatty acid isomers (23F),and also for methyl cis and trans mono- and dihydroxy fatty esters (83F). Hu et al. (40F) make use of argentation chromatography couple with GLC to determine chain len h and degree of unsaturation of fatty f fish oil, reversed-phase and aracid composition of I ilsha gentation HPLC has also been applied to cod liver oil FAME with a discussion of the mechanism of retention on low loaded AgN03-impregnated silicas (76F),and Scholfield (88F)describes the determination of long chain fatty methyl esters by HPLC using a silver nitrate-silica acid column and benzene solvent. Smith et al. (98F)present a method for measurement of trans and other isomeric unsaturated FAME from butter and margarine by argentation TLC followed by column chromatography and GLC, and Homberg et al. (37F)describe techniques for the determination of highly unsaturated FAME (with up to six double bonds) by TLC on silica gel impregnated with AgN03 and GLC. Koritala (490 reports on the GLC measurement of methyl linolenate in the presence of conjugated dienes, a technique is rovided for the on-line hydrogenation of FAME in capillary for structural analysis of complex mixtures of esters ( 5 3 ~ ) ,
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and Oehlenschlaeger and Gercken (71F) lxopose a procedure for the GC analysis of 1-monoacylglycerols as their cyclic carbonate derivatives with identification being made by MS. A method for the GC determination of polyunsaturated FAME on cyanoalkylpolysiloxane phasea is reported to provide novel acetylenic/ olefinic selectivity as compared to conventional polyester phases (43F),Neissner (70F)describes the TLC separation of positional isomers of monoesters from partial esters of fatty acids with polybasic alcohols, and Guebitz (32F) determines unsaturated fatty acids by densitometry using p-hydroxybenzaldehyde after their separation by high-performance TLC. Use is made of packed columns of temperature resistant stationary cyanopropylpolysiloxane phases for the GC separation of positional isomers of mono-, di-, and triunsaturated FAME and for resolving geometrical isomers (22F),a procedure is given for determining the positional distribution of the fatty acids in the trig1 cerides of mango kernel fat after preliminary extraction anCY TLC separation (109F),and Smith and Calder (96F)make use of GC-MS to analyze the ethyl-substituted fatty acids from lamb subcutaneous triacylglycerols. Methods are given for the GC measurement of short chain-free fatty acids in milk chocolate (115F)and in butter and cream (114F) wheriein the carrier gas is saturated with formic acid which minimizes peak tailing and extends column life, and Slover and Lanza (95F)report on the analysis of food fatty acids as their methyl esters by capillary GC using SP-2340 coated glass columns and note good column longevity even with high routine use. Chapman (19F),in determining the fatty acids of ve etable oils by GC, provides a modified esterification proce ure’ incorporating the use of thiourea during the preparation of the methyl esters which reduces triacylglyceride transesterification, a method is given (58n for the GC determination of FFA and their salts as the succinimidomethyl esters (using N-chloromethyl succinimide reagent), and use is made of naphthyldiazoalkanes as derivatizing agents for the HPLC determination of fatty acids from C1, to CI8(64F). Location of the furan ring in 2,5-disubstituted furan-containing fatty acids has been accomplished by GLC analysis of oxidation products with this technique applied to seed and fish oils (57F),methods are given (86F)for the GC analysis of underivatised fatty acids (C+&J using polyethylene gl col stationary phases on Chromaton N AWDMCS, anJSchwartz (!?OF)presents a simple method for obtaining saturated compounds from a mixture using a microcolumn of palladium chloride on silicic acid. A TLC procedure is presented (48F)for the determination of erucic and cetoleic acids as their methyl esters on silica gel plates impregnated with AgNO,, Blomstrand et al. (119 add a tagged carbon erucic acid methyl ester to rapeseed oils to effect the quantitation of erucic acid by GC-MS by use of the mle peak responses at 320 and 322, and a simple method is given (84F) which correlates the erucic acid content of rape oil to the time required for an oil solution prepared a t high temperature to become opaque on cooling. A modified copper soap method was developed (919 to provide a sensitive, rapid method for determining the FFA in milk, an ion exchange/derivatization procedure is described by Barcelona et al. (6F)fcir determining the C& fatty acids in aqueous samples, and an HPLC method is given for se arating Cz-C5 fatty acids (25F). Ke and Woyewoda ( 4 6 8 report a titrimetric method for determining FFA in tissues and lipids with ternary solvents and m-cresol purple indicator, Van Vleet and Quinn present a method (ll0F) employing highly polar GLC stationary phases for the determination of monounsaturated FAME, and Lam and Grushka (54F) describe a technique for labeling of fatty acids with 4-bromomethyl-7-methoxycoumarin via crown ether catalyst for fluorometric detection in HPLC (detection limits ranged from 9 to 90 pmol). A rapid coulometric method is iven (337 for the determination of iodine number by hyirogenation, and a coulometric titration with bromine in propylene carbonate of olefinic unsaturation in fatty acids is also presented (20F) with results comparable to those of the Wijs procedure. Honda et al. (38F) report a potentiometric method for determining iodine values of oils with an iodide-selective electrode, a procedure is presented for the determination of peroxide value by a modified colorimetric iodine method with protection of iodide as the cadmium coinplex (101F),and a technique for
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the rapid measurement of the acid value of oils which could be automated for control purposes is also given (3F). A new, simple method (117F)was developed for evaluation of the quality of frying oils and fats which is based on the change of relative interfacial tension of their cyclohexane solutions, Usuki et al. (107F, 108F) report on the estimation of oxidative deterioration of oils, foods, and frying oils by measurement of ultraweak chemiluminescence, and a technique is described for estimating the number of double bonds in a sample when using high-pressure differential thermal analysis to study the stability of FAME or triglycerides (116F). Takasago et al. (102F)report a new IR spectroscopic method for assessing oxidative stability of fats and oils, Witas (113F) provides optimum conditions for the determination of the degree of oxidation of fish oils through storage by the thiobarbituric acid method with alkaline hydrolysis. The GC analysis of octanoate is reported by Peers and Swoboda (79F) to provide an assay for monitoring the autoxidation of sunflower and linseed oil triglyceridesafter thermal decomposition of the oxidized oils and fats, techniques are described for the direct GC-MS determination of lipoxy enase generated linoleate decomposition products ( 1 0 0 4 , and a chromatographic sequence is given (75F) for the determination of products of thermooxidative alteration in heated oils. Ohyabu et al. (72F, 73F)present a simple method for determining the carbonyl value of volatile carbonyl compounds in assessing the rancidity of food fat, techniques.are presented for the separation of low-polarity lipid oxidation products by a combination of gel permeation chromatography and liquid column chromatography (77F),and Neff et al. (69F)describe methods used for the HPLC analysis of autoxidized lipids. Analysis of degradation products of oxidized methyl linoleate was achieved by gel chromatography and GC-MS techniques (68F), Maksimets (61F) provides IR spectroscopic methods for following oxidative and hydrolytic changes occurring in oils and fats during heating, and a direct spectrophotometric method with a monophasic reaction system is iven (478‘)for the microdetermination of thiobarbituric va ues of marine lipids. A portable instrument is described by Graziano (31F) for measuring the quality of frying fat in food service operations which relates the increase in dielectric constant of the oil to its rancidity, and Fritsch et al. (28F) compare rates of change of the dielectric constant of three shortenings and find rates of increase to be proportional to heating times. Gasparoli et al. (29F) make use of HPLC for the evaluation of edible oil stability, Kaya (45F) reports on a procedure for the fluorometric assay of malonaldehyde in autoxidized rapeseed and whale oils, Izaki et al. (42F) provide correlations of chemical indexes with deterioration of frying oils and fats, and Buzas et al. (16F)have shown that the oxidative stability of sunflower and rapeseed oils can be determined with a “derivatograph” with which thermogravimetric and derivative thermo ravi metric measurements were made and have also use! this device to study and characterizethe thermooxidative behavior of edible oils (17F). Frankel et al. describes quantitative GC-MS methods used to analyze autoxidized fats in soybean oil esters (26F) and in photosensitized oxidation products (27F),and Chang et al. (18F)describe techniques and methods used in their extensive investigations of chemical reactions involved in the deep-fat frying of foods. Analysis of the unsaponifiable matter of sunflower, soybean, pumpkin seed, rapeseed, and olive oils by GC-MS is reported (7F) and Maxwell and Schwartz ( 6 6 0 describe a rapid, quantitative procedure for measuring the unsaponifiable matter from animal, marine and ve etable oils. A rapid turbidimetric method is given by Brimterg et al. (1337for the determination of wax in sunflower seed oils, and Folstar et al. (25F) present a liquid chromatographic method for the analysis of coffee wax. A rapid TLC micromethod for fluorometric determination of neutral lipids is described by Lykkelund et al. (60F),an assay is reported ( 5 2 0 for plant sterols by use of cholesterol oxidase, and an investigation was made (51F) of the application of the acid-FeC1, method for determining the sterol content of seafood. A method is reported by Tsai et al. (105F) for the determination of cholesterol a-oxide in eggs by GLC after fractionation of the total egg lipids by column chromatography, HPLC and TLC methods are presented (59F)for the determination of coumestrol in soya beans, and Homberg (36F)provides TLC and GC methods for the identification of sterols in various lipids
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from swine. Use is made of a commercially available enzymic test kit for determining cholesterol in milk samples (30F),a simple GC method is reported (50F)for the determination of cholesterol and selected plant sterols in fishery-based food products, and Hsieh et al. (39F) provide a TLC method for campesteryl palmitate and sitosteryl palmitate in wheat flour. A colorimetric determination of sterols in vegetable oils is given (IF) using chloramine T and sulfuric acid reagent, Ballantine et al. (5F)have evaluated and find useful a C hydrocarbon stationary phase for analysis of marine sterofl in glass open tubular capillary columns, and Colin (21F) compares various systems for the separation of free sterols by HPLC. The phospholipid changes in actively metabolizing cells have been monitored by HPLC of 32Plabeled phospholipids ( I O F ) , a procedure is described (427)for the direct colorimetric determination of micromolar quantities of lecithin (employing enzymes as reagents), and Biacs et al. (8F) report on a gel chromatographic method for the fractionation of sunflower and rapeseed lecithin and GC analysis of fatty acids.
FLAVORS AND VOLATILE COMPOUNDS Mass spectrometric methods used for the analysis of flavors and flavor components are described in respective cha ters of two recent reference books (69G, 103G), Charalam\ous provides a useful reference book “Analysis of Foods and Beverages, Headspace Techniques” (18G),and a review which discusses compounds involved in food odors and flavors along with methods of analysis is presented by Parliment (79G). A technique for isolating flavor from fatty foods via solvent extraction followed by dialysis against pure solvent (usin a perfluorosulfonic acid membrane) has been applied to chedjar cheese and ground beef to prepare flavor compounds for chromatographic analysis ( I I G ) ,GC-MS analysis has been used to determine some 93 nonacidic volatiles from cooked mutton (74G) including 15 compounds not previously identified in cooked meats, and the volatile flavor compounds in the neutral fraction of roast beef were analyzed by Min et al. (70G)by repetitive GC trapping and GC-MS determination. GC-MS procedures are also reported for the analysis of flavors from smoked salmon and smoke tar (52G),for determining a smoked flavor condensate admixture to sausages (6G)using guaiacol and syringol as indicator compounds, and for the measurement of volatile products from mildly oxidized Pecan oil (41G). Biermann and Grosch (13G) report on a combined column chromatography/TLC method for isolating and identifying the bitter tasting monogl cerides from stored oat flour, and Luten et al. (64G) provile a GC method for determining phenol, guaiacol, and 4-methylguaiacol in smoke and smoked fish products. Lee et al. (55G)report on a combined headspace and extraction technique for profile analysis by capillary GC which they have applied to several systems including milk, coffee, and brandy, Legendre et al. (57G) describe an inlet assembly for use in analysis of volatiles of raw or processed foods by GC-MS which is claimed to not lose low molecular weight volatiles and is applicable to both aqueous and nonaqueous systems, and a procedure is given for the spectrometric determination of diacetyl in vinegar, wine, cheese, and butter via the formation of diacetyldithiosemicarbazone (29G). A colorimetric test is iven for the detection of wheat pasture flavor component ( esN) in raw milk (54G),Manning et al. (65G)report on GC comparisons of the headspace analysis of hard cheeses, and a technique is presented (27G) b which the flavor of meat products containing cottonseei proteins is objectively scored by instrumentally comparing ratios of hexanal hexanol to chloroform with results claimed to compare we 1with taste panel results. A TLC method is reported (99G) for determining aldehydes from foods as their dimethones, octahydroxanthenes, and barbiturates, Noda et al. (77G) describe the GC determination of volatile phenols in soy sauce, Merat (68G) determines formaldehyde traces by GC as its 2,4-DNP derivative from concentrated liquid flavors. The Working Grou on Methods of Analysis of the IOFI have provided a G 8 method for the determination of quassine from beverages (43G),Pate1 et al. (80G) report a spectrophotometric determination for eugenol in clove oil, and a spectrophotometric method is given for the determination of phen~ls(89G) by oxidation with sodium metaperiodate in the presence of acetic acid. White reports a new spectrophotometric method (107G) for determining hydroxymethylfurfural in honey, Graddon et
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al. (31G) describe methods used in their study of the volatile constituents of some unifloral Australian honeys, and HPLC sequences have been a plied (83G) as a technique to quantitatively separate foof flavorin pyrimidines, purines, and nucleosides, followed by nucleotifes; then by polyphenols and finally pyrazines. The ra id determination of quinine in soft drinks is performed ( 4 7 4 by use of reversed-phase ion-pair chromatography, Filthuth (26G) reports a method for the isolation and GLC analysis of benzyl alcohol from marzipan, and a method is given (28G) for the direct GC-MS analysis of neutral volatiles of mayonnaise. The GLC determination of pulegone in essential oils of peppermint is resented (66G) using tridecane as an internal standard, a G 8 method is also given for the determination of pulegone in mint essential oil, liqueurs, syrups, and confections (14G),and HPLC conditions are described for the separation of (-)-methone and (+)-isornethone (12G). Salveson et al. (85G)provide methods for the gas chromatographic separation and identification of the constituents of caraway oil, the HPLC analysis of li uorice is reported by Beasley et al. (8G),and Hoffman an% Salb (40G) have developed a method for the routine determination of the ori in of vanillin found in vanilla extracts and products by sta le isotope ratio analysis to differentiate vanillin from vanilla beans with that produced synthetically. A radioimmunoassay is described for the determination of nanogram quantities of limonin in crude plant tissue extracts or juice using a tritiated tracer (106G),methods are reviewed for the extraction and study of the volatile fraction of orange juice ( I G ) , and Beernaert and Gossele describe computerized GC-MS techniques for the determination of flavor components of essences added to soft drinks (JOG). A colorimetric method is given for the determination of carvone in volatile oils in the presence of menthone and pulegone (53G), capillary GC is used to provide a rapid method for the analysis of citral in lemon oil (32G),and Lund and Shaw (63G) report a GLC method for determining limonene in orange juice. Jurenitsch (49G) describe the GC determination of vanillylnonanamide after preliminary TLC separation from capsicum preparations, and GC (51G) and HPLC (50G) procedures are also given for the determination of total and single capsaicininoids of capsicum fruits. DiCecco reports a spectrophotometric difference method for determination of capsaicin (2IG),Johnson et al. (48G) make use of bisphenol A m an internal standard for the HPLC analysis of naturally occurring capsaicins, Sticher et al. (94G) analyze natural capsaicinoid mixtures and capsicum fruit by HPLC for capsaicin, dihydrocapsaicin, nordihydrocapsaicin, and homodihydrocapsaicin, and a method is given (46G)for the simultaneous microdetermination of capsaicin and ita four analogues by HPLC and GC-MS. Verzele et al. (102G)make use of HPLC techniques to analyze the pungent principles of pepper and pepper extracts (i,e., chavicine, isochavicine, isopiperine, and piperine), a GC method is given (35G) for measuring the isothiocyanate in Eruca sativa (a cruciferous seed) using fluorene as internal standard, and Spencer and Daxenbichler (93G) make use of GC-MS for the analysis of nitriles, isothiocyanates, and oxazolidinethionesderived from cruciferous glucosinolates. Hils (39G) has developed a spectrophotometric method for the determination of allyl isothiocyanate in pungent mustard seed and mustard, GC-MS methods are given for the determination of the volatile flavor of fresh jalapeno peppers (42G), and a TLC procedure is provided (30G) for the determination of pungent and related components of ginger. A new enzymic microdetermination for ethanol is described (4G)which uses a particulate alcohol dehydrogenase prepared from acetic acid bacteria, an automated enzymic method for measuring ethanol in alcoholic bevera es is also given (98G), Beaud and Ramuz (9G)make use of 8LC to simultaneously determine hi her alcohols and ethyl acetate in brandies, and Dupont ( 2 2 8 ) describes the determination of alcoholic strength of alcoholic beverages using a thermometric Auto Analyzer. Direct analysis of higher alcohols by glass capillary GC using dioxane as internal standard is reported (33G),and Marrum and Jaufmann (67G) make use of a fuel cell to determine ethanol in vapors and liquids by measuring the current roduced by its oxidation. A GC procedure is given for the &termination of agaricic acid in alcoholic beverages (59G)using cholic acid as internal standard, Dyer and Martin (23G) describe a GLC method for measuring y-nonalactone
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fermented plum juice (44G),to the volatiles obtained through in alcoholic flavors and beverages, and Bricout (15G)applies the formation of prunes (73G),to the comparison of fresh and HPLC to the analysis of aromatic aldehydes in brandy as well congelated apricots and pure6 of apricots (84G),and to the as other flavor ap licaticns. Woidich and Pfannhauser (108G) measurement of volatile constituents in cultivated strawberries provide a proce ure for the concentration and GC analysis (86G). of minor constituents of alcoholic beverages, Farley and Lehrian et al. (58G)describe a spectro hotometric method Nursten (25G) report on the GC-MS analysis of volatile flavor for measurement of phenols associate with the “smokycom onents of malt exi;ract after concentration with a L i b hammy” flavor defect of cacao beans and chocolate liquor, ens-kickerson extraction/concentration apparatus, a simple HPLC techniques are iven (36G) for the determination of and sensitive method is given (81G)for detecting trace flavor plant phenolics, Sephafex column chromatography was used components in beer by GC analysis after collection on Amto isolate polyphenol oxidation products in black tea infusions berlite XAD-2 resin and elution with ether, and Buijten and (24G),and methods are discussed (96G)which were used to Holm (16G) describe an automated system for determining isolate some 30 henols from roasted coffee and characterize diacetyl in beer. A HPLC procedure ie, presented for the these by GC-MfSmeasurements. Yamanishi reviews knowldetermination of hop bitter substances (JOIG)and Tress1 et edge regarding the aroma of various teas (109G),Nurok et al. al. (95G) report on their GC-MS determination of hop-aroma (78G)compare the profiles of sulfur-containing compounds constituents in beer (characterizing some 113 components with obtained from Robusta and Arabica coffees by capillary GC 45 of these reported in beer for the first time). Schimizu and analysis, and Gutmann et al. (34G) provide comparisons of Watanabe (90G) provide a GC technique for determining the aroma profiles of roasted Arabusta coffee with those of furfural (2-furaldehyde) and 5-hydroxymethyl-2-furaldehyde Arabica and Robusta varieties using enrichment techniques in wine, headspace analysis techniques are investigated (7.97, on Tenax polymers prior to capillary GC analysis. A technique 76G) for wines with emphasis on reporducibility of the GC for monitorin the staling of coffee is given by Arackal and techniques used, and Schreier et al. (87G) describe GC and Lehmann (5G7 who make use of the GC peak ratios of 2GC-MS techniques used to determine the neutral volatile methylfuran to 2-butanone as a correlatable measure of aroma constituents in grape brandies. GC methods are also given change and a measure of following the “freshness” of the for determining the flavor components of‘gin (19G)and the roasted coffee. high-boilingcomponents of rum by direct (trace) analysis (7G). The determination of sweet otato phenolics has been IDENTITY achieved by use of HPLC (105G7, and Walter et al. (104G) This section covers articles concerning the constituents of have also evaluated several methods for determining sweet foods and methods and information on the determination and potato phenolics, finding HPLC to be the most accurate detection of foods in foods. The sugars and nonvolatile acids technique and a spectrlophotometric ‘‘difference method’’ in 15 sam les of blackberries have been investi ated by (reading before and after sorption on a Rexyn 201 column) Wrolstad 6 9 H ) for the purpose of ac uirin basefine data to be adequate and the most rapid. TIE procedures are for establishing the authenticity of Blackierry products. provided for the analysis of pyrazines in roasted cereal flours Commercial chocolate produds have been analyzed by Zoumas (IOOG),Coleman et al. (2OG) have determined 31 pyrazines et al. (61H) for theobromine and caffeine contents, results are and 3 thiazoles in Idaho Russet Burbank baked potatoes by reported for chocolate liquor, commercial cocoas, sweet and gas chromatographicseparation followed by infrared and mass milk chocolates, chocolate beverages, and chocolate milk. A spectrometric identification, and Heisler and Siciliano (38G) total caffeine plus theobromine content of 3.5% has been make use of GLC to analyze stress induced sesquiterpenes suggested by Blumenthal et al. (223 as an average content (phytuberin, katahdinone, rishitin, and lubimin) isolated from of purine bases in cocoa solids, both an HPLC method and freeze-dried potatoes. Headspace techniques used for the a modified spectrophotometric method are described. Shea analysis of the aroma of virgin olive oil, changes in volatiles butter in cocoa butter has been detected by Derbesy et al. during olive ripening, and effects of processing on volatiles, are reviewed by Montedoro et al. (72G). A GLC method is (IIH) using GLC, total unsaponifiables separated by TLC and presented (71G)for the determination of phenolic compounds HPLC. Trig1 ceride com osition of cocoa butters has been in sunflower seeds, and Lund (62G)provides TLC and HPLC suggested by $adley et al. &OH) as a means of detecting cocoa techniques for the analysis of celery oil. HPLC is used to butter equivalents in cocoa butter using deviations from a determine methyl caffeate and ethyl caffeate in vegetables linear equation of selected triglycerides in cocoa butters. (92G),Ito et al. (45G) report on the GLC determination of HPLC and SDS-gel electrophoresis have been used by Hemlenthionin in shiitake mushroom, and GC-MS techniques are mati et al. (23H) to detect and quantify whey ingredients in iven (61G) for the determination of dried legumes (lima milk chocolate. Gradient gel electrophoresis of extracted eans, common beans, lentils, mung beans, soy beans, and split proteins has been applied by DuCros et al. (1323 to the peas). Simon et al. (91G) present an accurate and precise identification of varieties of wheat, barley, rye and triticale, porous-polymer trapping method adapted for the GLC and Shewry et al. (51H) have used sodium dodecyl sulfate analysis of volatiles from raw carrots, a method is presented polyacrylamide gel electrophoresis of gliadin for the varietal for the GLC analysis of 2,4-DNP derivativeel of monocarbonyl identification of single seeds of wheat. A 5-min test using compounds in carrots usin,g glass capillary columns (60G),and sodium hydroxide applicable to single kernels has been roButtery et al. ( I 7G) use direct capillary GC-MS and packed f posed by Lamkin et al. (34H) to distinguish red wheats o!m column GC and IR analysis to determine nine components white common, club, and durum cultivars. of the oxygenated fraction of the steam volatiles of carrot roots. The composition of green coffees has been reviewed by Geosmin, considered to contribute to the characteristic beet Poisson (42H) and the effect of roasting on the chemical aroma, is determined (9i’G) in beet juice by GC after exconstituents of coffee has been reviewed by Baltes (1H). traction with 1,1,2-trichloro-1,2,2-trifluoroethaneand Methods for the determination of the egg content of noodles “cleanup” on a column of Fplorisil, and a method is iven (56G) have been discussed by Burini et al. (4H)who conclude that for obtainin profiles of volatile compounds by 6 C analysis at least two procedures are needed to determine accurately of volatiles kom rice, corn products, and breakfast cereals. the whole eg s in noodles. The egg content of pasta has been A distillation-titration teclbnique (which is noted to correlate determined 6y Cauderay (5H)by the GLC determination of with organoleptic assessments) is provided (MG)for measuring cholesterol; no preliminary separation of lipids was re uired. the sulfide content of onions, the procedures are described The cu-amylase test for distin uishing unpasteurize! from which were used to determine a new volatile compound in pasteurized egg products has geen modified by Imai (25H) onion and leek (3,4-dimethyl-2,5-dioxo-2,5-dihydrothiophene) to im rove sensitivity. An enzymic method has been devel(2G), a rapid HPLC method is reported to determine hyoped \y Rehbein (44H) to differentiate fresh- and seawater droxymethylfurfural in tomato paste (3G), and Piva and frozen and thawed fish fillets, several lysosomal enzymes were Crouzet (82G) present a method for the determination of found suitable for the detection of thawed fillets. Thin-layer acetone and acetaldehyde in tomato ‘uice by isotope dilution isoelectric focusing has been found by Krz owek et al. (30H) (effecting isolation of the carbonyls dy forming the 2,4-DNP to provide protein pattern differences Ctween species in derivatives and then separating these by TLC). The detercooked crabmeat. mination of phenolic compounds in apple juices (e.g., phlorizin) The purity and origins of honey continue to be of great by HPLC is described (376),and GC-MS techniques are interest to many authors. White (55H) has published a review applied to the determination of flavor components from on honey including information on analysis and composition.
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Adulteration with high-fructose corn syrup has been verified by Lucchesi (3623) by mass spectrometric determination of the 13C-to-12C ratio after preliminary separation of the saccharides on a charcoal column. The mass spectrometric method has been studied collaboratively b White et al. (56H) and adopted official first action by the 1.O.A.C. However, with some results by this method White (58H)has noted that confirmatory action using TLC should be undertaken. A further test for honey adulteration has also been proposed by White et al. (57H) using a colorimetric test for 5-hydroxy-2furaldehyde. A TLC procedure for the detection of highfructose corn syrup and other adulterants in honey has been applied by Kushnir (31H) to material separated on a Celitecharcoal column. A further test for high-fructose corn syrup has been proposed by Doner et al. (12H) which uses GLC and measurement of the isomaltose to maltose ratio. Some of the amino acids in orange juice have been found to be affected by harvest data by Wallrauch (54H), who tabulated mean values and ranges for the individual amino acids for 152 samples. Trace element analysis of Florida and Brazil orange juice has been examined by McHard et al. (38H); Ba, B, Ga, Mn, and Rb and their ratios to Zn as a reference element may be used for characterization. The ratio of total nitrogen to amino acid nitrogen has been found by Roy0 Iranzo et al. (47H) to be a good parameter for judgin the composition of lemon juice. An immunoassay metho has been proposed by Firon et al. (16H)for estimating the orange juice content of commercial soft drinks with antiserum from rabbits. Methods of approximatin the apple juice content in apple juice beverages have been &cussed by Koch (29H). A pigment of pumpkin has been detected by TLC by Oke et al. (39H) which shows when red pumpkin has been added to tomato ketchup. Immunochemical detection of ovine, porcine, and equine flesh in meat products has been described by Hayden (22H) using rabbit and goat antisera. Electroimmunodiffusion has been applied by Sinell et al. (52H) to the quantitative determination of nonmeat proteins such as milk proteins in meat. Crossover electrophoresis has been found by Flego et al. (17H) to be more sensitive than double immunodiffusion for the detection of antigens in meat samples and thus for identifying a given meat sample. Protein differention with polyacrylamide gel electrophoresis and other electrophoretic methods has been found by Kaiser et al. (28H) to produce species-specific protein pherograms useful for meat and fish identification. Soybean and wheat proteins in animal protein products have been identified by Hashizume et al. (21H) by urea polyacrylamide gel electrophoresis, and an electrophoresis system on polyacrylamide gel with SDS could be used to identify soybean protein in cow milk and beef (2OH). Cooked sausage products have been analyzed for nonmeat proteins by Richardson (45H) using disk electrophoresis. An indication of the quality of ready-to-eat meals and canned roducts has been stated by Branka et al. (3H) to be obtainahe from the hydroxyproline and tryptophan content. The 3-methylhistidine content of food products has been used by Poulter et al. (43H)to estimate the lean meat content of food products. Peptide analysis by column chromatography after trypsin digestion has been applied by Llewellyn et al. (35H) to the determination of meat and soya proteins in meat products. A fluorometric technique for the quantitative determination of soy flour in meat-soy blends has been developed by Eldridge et al. (14H). Analysis of the tri- and 2-monoglycerides in the fat extracted from canned meat and sausages has been found by El Sayed et al. (15H) to provide means of detection of pork in these products. The orotic acid content of milk and powdered milk (assumed to be a minimum of 50 mg/L in reconstituted milk) has been used by Roesener (46H)to calculate the milk content in bakery products. Ratios of skim milk and whey solids in frozen dairy desserts have been determined by Peeples et al. (41H) from the protein and formol titration values. The replacement of nonfat milk solids with sweet-type cheese whey has been monitored by Josephson et al. (26H) by measuring lactic acid, lactose, protein, and gl comacropeptide precipitation. Studies of the amino acic?composition of defatted whey powder have been made by DeLange et al. (1OH) and compared with that of fresh milk, casein, and whey. A quick, simple method for the determination of sesamolin and sesamin in sesame oil has been described by Yoshida et al. (60H) using column chromatography and HPLC. Pomace
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oil in commercial olive oils has been determined by Spencer (53H)by GLC measurement of the ratio of 24-methylenecycloartanol to cyclobranol. Composition data on dietary fats, oils, margarines, and butter has been reviewed by Sheppard et al. (50H). A computer program has been established by Kacprzak et al. (27H) for the automatic identification of edible oils by GLC using fatty acid ratios. A symposiuim conducted by Chung et al. (8H) has been published covering discussion of li id com osition and other data for wheat, rice, corn, sorgium anfpearl millet, and oats. Argentation TLC for triglycerides and GLC for fatty acids have been used after lipolysis by Colombini et al. (9H) to investigate the presence of beef suet and lard in butter. Ambadi seed oil in ve etable oils has been detected by Grover et al. (19H) by TL8of the unsa onifiable fraction. Taramina oil in mustard and rapeseed oils {as been detected by Grover et al. (18H) after steam distillation and TLC of the ether extract of the distillate. Paper chromatography of a hydrochloride extract of the oil has been used by Chakravorty (6H) to detect down to 5% of rapeseed oil in mustard-seed oil. The hexabromide test has been applied by the same author (7H) to the semiquantiative estimation of linseed oil in mustard-seed oil. Vinegar produced by fermentation and vinegar made from synthetic acid have been differentiated by Schmid et al. (49H) by determination of their tritrium activity. Data on authentic vanilla extracts have been presented by Martin et al. (37H),including total and free amino acids, vanillin, nitrogen, phosphorus and potassium. Hoffman et al. (24H) have determined the 1'3Cto 2C ratio in vanillin prepared from extracts by preparative GLC and the results make it possible to distinguish synthetic from natural vanillin. Pattern recognition of the results of GLC analysis has been applied to the quality evaluation of whiskies by Saxberg et al. (48H).Similarly Kwan et al. (33H) have applied mineral analysis for 17 elements to some French and United States wines and (32H) to Rhine and Moselle wines; for these wines data obtained from GLC analysis were also included in the patterns.
INORGANIC Several reviews dealt with techniques useful for a wide range of inorganic analyses on foods. Fricke et al. ( 3 1 4 listed many elements amenable to atomic absorption analysis with instrumental conditions and sample treatment. Jones et al. (514 discussed applications found in the literature for inductively coupled plasma elemental measurement in food. Comer (154 reviewed publications about ion-selective electrode methods. Fry et al. ( 3 2 4 discussed the occurrence of molecular absorption when complex matrices were aspirated into flames for analysis. Kapel et al. (544 reported determining 12 elements in foods by cathode-ray polarography techniques. Tsai et al. (1094 reported improvements in the technique of ashing oils for heavy metals analysis by atomic absorption. Williams (1214 emplo ed pol styrene containers to digest samples with concentrateiacids gefore instrumental mineral analysis. Feinberg et al. (255) compared nitric and sulfuric acids as dry ashing aids and favored sulfuric for heavy metals analysis of high rotein samples. Continuous digestion at a rate of 15 samples/! with a sulfuric acid-peroxide system was achieved by Budna e al. (1w) in hot-block apparatus with moving tubes. Agemian et al. ( 3 4 modified an aluminum hot block to digest fish for Cr, Cu, Zn, Cd, Ni, and P b traces. Barrett et al. (54 gave their design of a microwave oven apparatus to reduce wet digestion times for fish to minutes before mercury analysis. Kotz et al. (645) favored glassycarbon pressure digestion vessels for mineral analysis and gave details. Arsenic was determined by both graphite furnance AA and arsine evolution/color reaction and found to agree for animal tissues by Lo et al..(704. Yasui et al. (1255) used back-extraction and oxidation treatments to separately measure Asm AsVand or anically bound As from fish and plant material. Fricke et af (304em loyed sodium borohydride reduction to liberate h drides of 8e, As, Sn, Se, and Sb whch were swept through a 8hromosorb 102 column into a plasma emission spectrometer relatively free from volatile interferences. Robbins et al. ( 9 1 4 used the former scheme to analyze flour and blood for those elements and reported optimum acidities for hydride liberation. Evans et al. (245) used a heated silica tube in the AA beam to quantify liberated hydrides of Sb, As, and Sb after wet oxidation foods. Dornemann et al. (224
FOOD
analyzed for very low traces of antimony in liver samples, digesting in H2S04-HN03before using a similar final measurement. Differential pulse anodic stripping voltammetry from a hanging mercury drop was shown to agree with the fluorometric method by Forbes et al. (294 who used oxygen combustion to mineralize their dry samples. Ishizaki (484 injected selenium extracted into dithizone/CC14solution into a graphite tube AA apparatus for flameless measurement after oxygen flask combustion. Watkinson (1174 described a scheme for selenium traces that automated the naphalene2,3-diamine fluorometriccomplex formation and measurement after manual digestion. Sydlowski et al. (1064 claimed considerable time saving by modifyin a semiautomated wet digestion procedure for selenium be ore automated fluorometry. Horwitz (474 reviewed methods for tin in foods at trace and higher concentrations. An advantage in sensitivity in the measurement of liberated stannane by using a 60 cm long cell for atomic abisorption was reported by Nakashima (824 for fruit juice analysis. A method to measure tin hotometrically with a hemotein reagent was studied by TsuEada et al. (1104. Yamamoto et al. (1234 utilized an oxidized hematoxylin reagent to develop an improved colorimetric procedure for tin in canned juice. Tin was determined in the presence of lead by anodic stripping after isolation by a double extraction in work by Waggon et al. (1224. Polished rice was partially ashed in a low-temperature oxygen asher before wet digestion, complex extraction, and flame AA measurement in the method of Narasaki (834 for cadmium. Dabeka (174, after wet digestion of foods, modified the APDC/MIBK extraction system to provide better selectivity and sensitivity for his gra hite ffurnace Pb and Cd measurements. A comparison of ggestion methods for soup Sam les before flameless and hydride generation AA spectro Rotometry was made by Knezevic et d.(624 for lead, tin, a n i iron analysis. Holm ( 4 6 4 reported a simple digestion and flameless analysis scheme for Pb, Cd, and As in animal tissues. Lund et al. (734 aimed their study at oyster tissue, employing anodic stripping after wet acid digestion. Lautenschlaeger et al. (684 employed sealed acid digestion vessels to avoid losses from coffee samples before a combination of flameless and flame AA measurements for Hg, As, Cd, and Pb. Results for direct anodic stripping analysis of lead in fruit juices using Metexchange reagent were reported by Zink et al. (1264. Sulek (1055) enumerated the results of a collaborative study on lead in milk by anodic stripping and atomic absorption methods. Jones et al. (525) commented on means of improving sample hoimogeneity in canned food analysis for lead content. Bound metals in wine were released by using peroxide and UV energy before stripping analysis for Pb, Cu and Cd in the method of Golimowski et al. (354. Combined wet and dry ashing was useful to Fetterolf et al. (274 to destroy tenacious organic material in analyzing chewing gum for lead traces. Kupchella et al. (674 later used the same ashin to analyze for Ni, Mn, Cu, and A1 by carbon tube AA. Da &ta et al. (194 concentrated lead traces in fruit juices on Corning immobilized ED 3A before elution and flameless AA. Schuetze et al. (954 studied the Cu, Fe, Ni, Zn, Pb, and Cd that was bound to fats using flameless AA techni ues. Copper taken up by fish was followed by monitoring aY5Cu tracer by spark source mass spectrometry in work by Harvey (44J). A colorimetric method for copper in alcoholic beverages reagent was described using 6-phenyl-1,2,4-triruine-3-thione by Karapetian et al. (554. Advanta es of' a tungsten carbide coated crucible for flameless AA fetermination of copper traces were given by Norval (844. A simultaneous method for copper and mercury using gold electrode for anodic stripping was given by Sipos et al. (1034. Rigin (904 thermally desorbed mercury from a gold cathode after electrode deposition, measured the vapor by atomic fluorescence and applied the method to foods. Agemian et al. (24 automated the reduction and cold vapor stages of a simultaneous Hg/As procedure for fish. Davidson (215) claimed that the use of 50% HzO2in a hot block gave superior digestions for fish before cold vapor Hg measurement. Their version of a VzO5 catalyzed digestion was described by Knechtel et al. ( 6 1 4 for mercury trace analysis. Naganuma et al. (814 studied the action of selenium in causing low recovery in a digestion/cold vapor mercury procedure. Combustion in an oxygen stream, KIMnO, trapping, reduction to vapor, and silver wool preconcentration were used by Watling (1184
!
in his Hg methodology. After sample injection into an aeration cell, the Hg vapor generation sequence was automated by Velghe et al. (1135)in their cold vapor method. Improvements in the recovery of Hg were described by Shoka et al. (994 that incorporated butyl acetate extraction and the presence of Cu2+ during vapor generation. Methylmercury was released and dithizone extracted before a graphite furnace AA analysis in the paper by Shum et al. (1014. An atomic absorption unit was used as a specific Hg detector after gas chromatography of alkylmercury compounds and pyrolysis after separation in the work applied to fish by Bye et al. (134.Methylmercury residues in food and biological samples were determined by electron capture GC after extraction by Cappon et al. (144. Gvardzancic et al. (404 transferred methylmercury vapor to cysteine impregnated paper before solvent extraction and GC final measurement in their version of a method. MacCrehan et al. (744 employed electrochemical detection of organomercury compounds after liquid chromatography of fish extracts. Nose (854 utilized a thin-la er chromatographic cleanup before digestion and atomic a sorption for organic Hg species in rice. A dual wavelength correction approach was found by Jones et al. (534 to remove errors due to excess dithizone reagent in a colorimetric method for methylmercury. Potassium at levels of lo-' to 10-l' mol could be measured by its effect on a pyruvate kinase catalyzed reaction stage in a method b Outlaw et al. (874. Silva et al. (1024 prepared and studiedrbenzil bis(2-hydroxybenzohydrazone)as a useful calcium spectrophotometric reagent for food samples. An automated flow system without segmentation was applied to Ca in milk by Basson et al. ( 6 4 and could colorimetrically analyze up to 180 samples/h. An automated version of the a-phenanthroline AACC method for iron in cereals was improved by mixing buffer and sam le streams after reduction in a report by Loewe et al. (71& May et al. (754 made use of Mossbauer spectroscopy to determine the bound form of iron in wheat enriched with 57Feduring growth. An analytical scheme to determine iron in different complexed and valence states in food using bathophenanthroline reagent was discussed by Lee et al. (694. An atomic absorption measurement of beryllium in foods using acetylacetone chelating was published by Y amanobe et al. (1244 and used an Nz0-C2Hz flame. Schramel(944 found he could analyze for boron in milk by direct sample aspiration. A method suitable for 1-2 ppm of aluminum in foods using aluminon reagent was given by Klaus et al. (594. Reis et al. (894 assembled an automated flow injection analysis system sensitive to low ppm levels at a rate of 120 per h. Manganese in soft drinks was subjected to spectrophotometry after complexation with 4-benzoyl-3-meth 1-1-phenylpyrazolin-5-one in the procedure of Akama et al. A zinc-dithiol/MIBK solvent system was used to extract molybdenum from plant wet digests before AA measurement by Khan et al. (574. Daniel et al. (204 dry ashed samples at 540 "C before complexation and solvent extraction and then injected the complex into an atomic absorption NO/CzH2flame to minimize carbon deposits. A continuous flow injection method capable of doing 30 Mo determinations per hour as the thiocyanate complex was discussed by Bergamin Filho et al. (74. Veillon et al. 1124 used a GC/MS method to determine 52Crby adding l0Cr before ashing and trifluoroacetylacetone complex formation. A new reagent for vanadium colorimetry, N44chloropheny1)cinnamohydroxamic acid, was reported useful for vegetable analysis by Roshania et al. (925). A scheme for neutron activation analysis of vanadium traces in seafood samples that removed Na and C1 to improve sensitivity was given by Blotcky et al. (94. Cobalt was extracted with trioctylamine by Oyamada et al. (884 from d z ash solutions previous to graphite tube AAS. The level of Sr in milk was inferred by analysis for poYwhich was extracted, precipitafRd with added 89Y as the oxalate, and measured by 8 countin in work regorted by Mitsuhashi (794. Kimura et al. ( 5 8 j separated Sr and 8gSrfrom milk with a crown ether-chloroform milk ash solution liquid-liquid extraction. Kracke et al. ( 5 4 gave a technique for wet ashin large amounts of food sample for trace actinoids such as 8Pu. The use of a specific electrode for fluoride in milk was and suggestionswere made investigated by Smith et al. for decreasing interferences. Dabeka et al. (184 diffused fluoride from sam les as HF and measured F- in a tra ping solution with an eEctrode in a method for foods. McEPfresh
64.
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(low,
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(775) made use of an ion exchange Amberlite CG-120 column to treat a water extraction of potato tops for improved quantitative electrode P measurements. A collaborativestudy on two trace fluoride methods for beet pulp and molasses was reported by Koster et al. (635) and the electrode approach found comparable to the thorium nitrate titration. Hanocq ( 4 2 4 used microdiffusion before colorimetry with Cem alizarin complexan reagent in aqueous dimethyl sulfoxide. Tea leaves were investi ated for F- content by Feldheim et al. (265) who dry ashed, &stilled WF and performed measurements both colorimetricallyand potentiometrically. Chloride in wines was analyzed by Gonzalez Perez et al. (365) as the chromyl chloride complex extracted into CCl Kubadinow et al. (665) made use of barium and mercuric choranilate reagents, respectively, for sulfur and chloride analysis in sugar beets. Varga et al. (1115) discussed various automated analytical schemes to determine chloride and nitrate in meat. Bromide residue analysis in crops could be done by a thin layer procedure that formed eosin from fluorescein on the plate in a rocedure by Gordts et al. (375). Iodide could be estimatecfin raw milk by a specific ion electrode according to a study by Bruhn et al. (105). Fukazaki et al. (344 in a method for rice, performed a preliminary CC14extraction of I- after conversion to Io and then reconverted to I- for electrode measurement. Miles (785) found direct electode analysis of beverages useful and comparable to other methods. Gstrein et al. ( 3 9 4 showed how to make stable corrections for interferences to an automated catalytic iodine trace procedure, Moxon et al. (804 reported a semiautomated total iodine method based on iodide moderated catalytic destruction of thiocyanate by nitrate. Jones et al. (504 studied dry alkali and wet acid ashing for iodine-125 recovery and favored the former for vegetable material. A method for thiocyanate in eggs was published by Shuaib et al. (1004 wherein SCN- is converted to CNBr which is extracted and subjected to ECGC. Schmidt (935) performed direct injection of fruit juices onto an inert packed column coated with Carbowax 1500 to measure hydrocyanic acid with a N-specific detector. Powdered beans were assayed for cyanide content after equilibrium with McIlvaine’s buffer, steam distillation, and colorimetric quantitation by Katsuki et al. (565). Cooke (165) analyzed cassava after @glucosidase treatment of an extract which was then subjected to color development with chloramine/pyridine-pyrazolone. A gas chromatographic procedure for cyanide in wine using EC detection of cyanogen bromide formed was reported by Addeo et al. (14. A modification of the Monier-Williams SOz method was published by Wedzicha et al. (1195) in which they added a colorimetric measurement such as Humphrey’s method. A pararosaniline-formaldehyde color reaction applied to distillates from a modified Rankine apparatus was found to give superior results for red wine samples by Ogawa et al. (865). Homano et al. (415) investigated free and combined sulfites in foods, employing headspace GC and flame photometric S detection. Fujita et al. (335) modified a Rankine apparatus to enable sample injection instead of aspiration and found less combined SOz breakdown when measuring free SO2 by this technique. Bruno et al. (115) recorded olarographic signals from free and total SOz in wine added 8rectly to a dimethyl sulfoxide LiCl HzS04electrolyte. Dissolved air in beer was estimate by isk et al. (285) using a disposable syringe and tubing to make a minigasometric apparatus. Ishizaki et al. (495) reported good results from a method that measured formaldehyde colorimetrically formed by catalyze action on methanol and peroxide. Elemental sulfur in foods was extracted with petroleum ether and detected at 263 nm after HPLC on an RP-18 column in the method of Wenzel (1205). McCracken et al. (765) automated a molybdate reaction for phosphorus determination in grains that measured the color developed in 5 s. Phosphorus NMR spectra were used by London et al. (725) to investigate phospholipid composition. A method for total phosphorus in lipid materials using alkaline digestion in PTFE crucibles before molybdenum blue color formation was described by Hartman et al. (435). Grey et al. ( 3 8 4 detected polyphosphates in chicken meat after a trichloroacetlc acid extraction and by difference after hydrolysis of the extract. Walters et al. (1145) determined nitrite at low levels in food samples by forming NO and stripping it, scrubbing it, and measuring it in a flow-through chemiluminescence analyzer.
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Walters et al. (1165) also described using this final chemiluminescent measurement as a means to measure low nitrate and nitrite levels after separate conversion steps to NO. Hart et al. (1155) had discussed other species of compounds that could also degrade to NO and cause interference. Terada et al. (1084 reported nitrate measurement by HPLC separation and Tanaka et al. (1075) reacted nitrite in foods with 1,2diaminobenzene to form 1-H-benzotriazole which was then solvent extracted, converted to a TMS derivative, and run on FID gas chromatograph. Sen et al. (985) recommended a different sequence of reagent addition to the diazotization method for nitrite analysis to reduce ascorbic acid interference. Sen et al. ( 9 7 4 ,in analyzing nitrite and nitrate by colorimetry, added an extra ion exchange step to facilitate application to difficult sample types. The substitution of N-1-naphylenediamine for 1-naphthylamine as nitrite/nitrate reagent was investigated by Sen et al. (965) with respect to reducing blank values. Klepper (605) added MeC1, and PVP to aqueous plant extracts to clarify them and improve nitrite recovery. The effects of pH and NaCl concentration were reported by Hildrum (455) as they caused variability in the nitrite coupling color reaction. Additional data on the use of phenol as a nitrate reagent were given by Elton-Bott (235) with some advantages cited. Some work on the fixation of the nitrate position in foods was reported by Biedermann et al. (85).
MOISTURE The Mitchell and Smith reference, “Aquametry. Part 111. A Treatise on Methods for the Determination of Water”, appears in its second edition (14K). The status of fundamental and practical reference methods developed under the aegis of the International Association for Cereal Chemistry (ICC) is reviewed (17K),including descriptions of suitable commercial equipment identified for sample preparation and moisture measurement. Roedel et al. (20K) describe instruments and techniques for measuring the water activity (a ) of meat and meat products including a sensor developea for surface measurements (e.g., of carcass meat), and Muffett (16K)reports on the determination of bound and free water relationships in soy proteins as measured by differential scanning calorimetry over a range of concentrations. Equations for predictin the A, of aqueous solutions in connection with interme iate moisture foods are given for strong electrolytes (6K) and for nonelectrolytes (3K), and a technique is also provided for predicting moisture transfer in mixtures of packaged dehydrated foods (IOK). Quinn and Paton (18K) rovide a practical centrifugation measurement of the water ydration capacity of protein materials, and Coelho et al. apply inverse-phase gas chromatography (5K)to the determination of bound water in collagen. A collaborative study of three variations of the Karl Fischer titration method for water in foods (corn starch, wheat flour, and raisins) is reported by Hadorn (9K),a description is given (15K) of a new microwave moisture meter for grains with results claimed to be rectilinear against those of an oven drying method for different s ecies of rice for up to 18% of HzO, and microwave moisture dPevices were also found to be suitable as compared against standard oven methods for the rapid determination of moisture in hops (7K) and for the measurement of total milk solids (21K). Bjorkqvist and Toivonen ( 2 K ) describe a technique for measuring water by reacting it with phenyl isocyanate to form 1,3-di henylurea which is then determined by reversed-phase H P L 8 and the application of the Ultra-X-Analyzer (an instrument based on IR spectrometry) to the measurement of moisture in various types of fresh fish is presented by Lang (12K). An apparatus for the continuous determination of moisture in foods by measurement of the dielectric constant is described ( B K ) and Benard (1K) reports on the adaptation of a commercial electronic densitometer to the automatic
d
K
with electrical report that pulsed NMR was found to be satisfactory for measurement of moisture in barley, corn, grain sorghum, and wheat at levels from 15% to 40%. Measurement of the dielectric constant is suggested as a rapid means of monitoring the moisture content of ghee during “boiling down” (11K), and Richardson et al. (19K) make use of a vapor-phase OS-
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mometer to determine added water in milk and report that results correlate well with those obtained by cryoscopic methods. Results of a collaborative study are reported by Clinton et al. (4K) which resulted in the establishment of an acceptable routine working method for determining mass loss on drying for instant coffee with the reproducibility standard deviation and coefficient of variation being 0.153 and 3.8%, respectively.
OR(GAN1C ACIDS A review by Trommsdorff (56L)gave extensive references to methods utilizing as chromatographxc techni ues to analyze for organic acid and esters. Lunder et al. 728,) used an amino acid analyzer instrument to separate 10 mono- and dicarboxylic acids commonly found in foods. A pH 3.1 leading electrolyte separated fumaric, ascorbic,tartaric, malic, succinic, and citric acids while pH 8.8 functioned for lactic and oxalic in an isotachophoretic study by Kawabata et al. (24L). Kaiser et al. (23L)also discussed the principles and applications of isotachophoretic acid sleparations. Mayer et al. (30L) conipared differential pulse and direct current am erometric detection after LC separation of oxalic acid. A rapifenzymatic procedure based on Aspergillis oxalate decarbox lase was reported by Beutler et al. (6L)for fruit and vegetahe juices. Reinefeld et al. (4515)determined formic acid directly in diluted molasses with formate dehydrogenase, avoiding preliminary separations. Rabe (42L)showed ood recovery in applying an enzymic scheme for lactic a n 8 acetic acids in sour dough. A gas chromatographic difference measurement of acetic acid before and after KMn04 oxidation was used by Kratochvil et al. (26L)to measure the acetic and lactic acids in rye sour. Hikuma et d.(19L)reported being able to sense acetic acid levels in a flowing system with an amperometric oxygen electrode and immobilized microbes. L-Lactic acid and ethanol were measurable at a carbon paste electrode containing immobilized NAD in procedures described by Yao et al. (64L). Elbertzhagen ( I 7L) discussed interferences in enzymatically determining pyruvate in milk and suggested solutions. Ahmed et al. ( I L )reported orotic acid levels in milk as determined by TMS-GC after cleanup. Volatile C1 to C5organic acids were initially separated from food by steam distillatioin and then converted to benzyl esters for GLC analysis in work by Staruszkiewiar et al. (50L). Arbin et al. (ZL, 3L) investigated phase transfer catalysis as a way of esterifyin organic acids before GC analysis, especially where hydrofytic degradation was a problem. Conductivity in water-pyridine systems was utilized by Okayama et al. (38L) to achieve responses from beverages correlating to alkali titration. Miwa et al. (3i'L)modified a colorimetric method based on 2-nitrophenylhydrazine reaction to measure aliphatic, aromatic, and amino acids. Makamaura (29L)reacted yruvic and a-ketoglutaric acids with N-methylnicotinamife by a post-LC column treatment to achieve higlh fluorometric sensitivity. Lindner et al. (27L)derivatized organic acids with N-(chloromethy1)phthalimides before HPLC separation and UV detection. Long chain acids of ClS to1 C size were separated by gel permeation and refractive index detection in work by Wilhelm et al. (63L). The acetic, D-lactic, L-lactic, and citric acids were assayed in soy sauce by the addition of appropriate analytical enzyme reagents directly to a sample solution that had been pretreated with other enzyme reagents in the procedure of Yoshihara et al. (65L). 0 ura et al. (37L)injected soy sauce directly into an HPLC cofmn to measure lactic acid. A collaborativestudy of two methods for total volatile acidity in wines was described by Pilone (4IL)and a comparison of repieoducibility made, Columns of Aminex A-25 and RP-18 were used to separate stronger and phenolic acids from wine, respectively, in work by Symonds (52L). GC after formation of trimethylsilyl and trifluoroacetyl derivatives of red and white wine organic acids was used by Bertrand et al. (5L)to study composition down to 50 ppm levels. Malic acid in colored fruit juices was found measurable with higher specificity by Reinhardt et al. (46L) when HzS04 reaction concentrations were optimized before chromotropic acid color development. Wallrauch (59L) reduced interference to the chromotropic color development with NaBH, reduction and 851OC temperature control. Brunner et al. (7L)also used borohydride reduction but found color development for 50 min ,st 0 "C optimum to suppress interference. A small precolumm of C18/PartisilE% served to cleanup
cranberry juice before HPLC separation of quinic, malic, and citric acids in work by Coppola et al. (14L). Battle et al. (4L) substituted dialysis for carbon cleanup in a continuous flow analysis of tartaric acid in grape musts and wines. Malic and citric acids in apple juice were measured by monitoring at 220 nm after Jeuring et al. (22L)injected samples directly onto a reversed-phase HPLC column. Citric acid in vegetable oil was extracted with hot water before polarographic measurement in a method by Vinyukova et al. (58L). An enzymic procedure based on isocitric dehydrogenase was found suitable for estimating orange juice content of beverages by Calabro et al. (9L). Buslig et al. (8L) automated a similar enzymic method and studied variation among varieties of oranges and grapefruit. The free acids of the citric acid cycle were separated from juices and biological samples b HPLC on Aminex 50 W-X4 resin and detected at 210 nm %yTurkelson et al. (57L). Stumpf et al. (5IL) published a GC method for tricarboxylic acid cycle acids in soya beans that utilized TMS derivatives after preliminary ion exchange isolation. The I.O.F. (2OL)recommended a method for agaric acid suitable for alcoholic beverages or candies that used GLC of its TMS derivative. Ito et al. (2IL)methylated adipic acid with diazomethane prior to its GC determination in candy and beverages. Schmidt et al. (49L)used colorimetry with vanadate reagent to determine tartaric acid in esterified monoglycerides. The methyl ester of abscisic acid was separated by HPLC after diazomethane reaction of a potato extract in a method by Cargile et al. (IOL). The phytic acid content of rice bran was measured by Tangendaja et al. (54L) using reversed-phase HPLC on a c18 column. Ong et al. (39L) studied the composition of hydroxycinnamic acid-tartaric acid esters in grape juice, utilizing polyamide column fractionation before an analytical separation on ODS by HPLC. Phenolic acids in cherry juices were trimethylsilated and separated by GC using 4-hydroxybenzoic acid as internal standard in an investigation by Tanchev et al. (5315). Nagels et al. (33L) repared derivatives of quinic acid and related acids using p-iromophenacyl bromide before HPLC separation was affected. Isohumulone and isocohumulone in beer were extracted and subjected to HPLC by Whitt et al. (62L),monitoring the column effluent at 280 nm. Walter et al. (6IL)found 313 nm to be the proper wavelength to measure sweet potato phenolic acids emerging from a C1 reversed-phase column. Walter et al. (60L) also compareJ several methods for the analysis of sweet potato phenolics and found binding to a polymer with a resultant UV absorbance change to be rapid and accurate. Schulz et al. (48L)detailed extraction, hydrolysis, and a TLC procedure for the analysis of bound hydroxybenzoic and hydroxycinnamicacids in plants. A preliminary report on utilizing various HPLC separation and detection techniques for citrus phenolics and phenolic glycosides was issued by Rouseff (47L). Moll et al. (3%) found more than 20 species of phenolic compounds from beer easily separated by reversed-phase HPLC using 2% ethanol in water as solvent. Otter et al. (40L) studied conversion of a-acid to iso-a-acid in hops by performing chromatographyon a column of phenyldiethanolamine silica. A method for tannic acid in beer using the Prussian blue test after TLC was described by Dadic et al. (15L). Kozubek et al. (25L) analyzed r e and wheat for 5-n-alkylresorcinolswith HPLC on LiChrosorg RP-2 and UV detection. Soya bean p l a t leaves were examined for their phenolic and flavonoid content by injecting 2% acetic acid extracts directly onto a (218 reversed-phaseHPLC column in a study by Hardin et al. (18L). Coomans et al. (13L) reported methods of determining tannins in tea indirectly by precipitation with Cu2+and measurement of excess copper by specific-ion electrode and atomic absorption. The phenols and diphenols of different strains of roasted coffee were investigated by Tress1 (55L) using column chromatography and GC MS of TMS derivatives and found to vary with origin an roast. Nakabayashi (34L) reported changes in 10 carboxylic acids found in coffee as a function of roasting. This author (35L) also theorized on the origin of acids from sugars and complex carbohydrates in coffee. Rahn (43L)described the results of steam treatment of reen and roasted coffee on the phenolic constituents. Rees $44L) utilized HPLC and colorimetric methods to measure chlorogenic acid isomers in coffee varieties. Nakabayashi et al. (36L) followed changes in coffee bean quinic acid levels as a function of roasting using silica gel column chromatography. Clifford
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(11L)reviewed methods and findings for chlorogenic acids in coffee. Clifford et al. (12L)reported a comparison of six methods for chlorogenic acids in reen coffee beans and favored a periodate reagent one. !‘he course of reaction of chlorogenic acid by depsidase catalysis was followed by a reversed-phase HPLC separation in a paper by Dumont (16L). NITROGEN Reviews on the determination of nitrogen have been published by Lakin (61M)and Jacobs (51M). The use of titanium dioxide and cupric sulfate as catalyst for macro-Kjeldahl has been tested by Yasui et al. (124M) and found satisfactory for foods with low levels of nitrogen. An antimony-based catalyst has been investigated by Bjarnoe (5M) in the Kjel-Foss analyzer and found equivalent to the usual mercury catalyst. A rapid procedure for total nitrogen in plants has been proposed by Sharma et al. (99M) using potassium dichromate or chromic oxide as an aid to rapid digestion. Nitrogen in milk has been determined by Lin et al. (66M) by Conway microdiffusion, instead of microdistillation, after digestion. After reaction with powdered aluminum at 550-650 “C, the amount of nitro en in plant samples has been found by Osadchii (85M) to e related to the amount of trivalent aluminum which is determined titrimetrically. Total nitrogen in plant digests has been determined by Zagatto et al. (125M) using Nessler reagent in a flow injection system with an isothermal distillation unit. Protein has been determined by nuclear magnetic resonance with the help of a relaxation reagent by Coles (15M), and in starch products by 14-MeV neutron-activation analysis A new method for fast protein deby Fanger et al. 0. termination has been described by Varga (116M)with A(d,p)B-typenuclear reactions and applied t~ the determination of protein in cornflour and maize. Deuteron irradiation of wheat has been used by King et al. (55M) to measure the protein; the measurement of the nitrogen peaks in comparison with the carbon peak was used for tKe determination. Near-IR spectrometry has been found by Williams et al. (123M) to be capable of automation and has been used to analyze up to 2500 samples of grain for protein per day. The biuret method has been shown by Turgut (112M) to give different results on fresh fish samples compared to the same fish that had been frozen and then thawed. Solubilized meat proteins have been analyzed by De Wreede et al. (2OM) by a biuret method using beef serum albumin or gelatin as a standard. Total nitrogen has been determined in soybean protein fractions by Nakamura et al. (79M)with a chemiluminescent nitrogen detector; ood reproducibilitywas obtained. Dye binding has been used gy Seperich et al. (98M) to monitor the protein content of meat components and sausage emulsions with the use of regression equations. Kroger et al. ( 6 0 have found that the dye binding procedure is affected by the presence of proteins containing reduced or elevated contents of basic amino acids, the method has been applied to ice cream but is only useful on uncolored ice cream. Protein precipitants have been compared by Greenber et al. (34M) on protein hydrolyzates and protein, and the atility to precipitate varies with both the protein and the precipitant. Thin-la er isoelectricfocusin on polyacrylamide gel has been found gy Goerg et al. ( 3 1 d to improve separations of proteins extracted from vegetables. A simple colorimetric method using Coomassie Brilliant Blue R-250 has been found useful by Esen (23M) for zein determination in corn after paper chromatography. Gliadins from wheat flour have been fractionated and purified by hydrophobic-interaction chromatography on Sepharose CL-4B by Caldwell (12M). A method for determinin the degree of hydro1 sis of food protein hydrolysates has geen developed by Aldrer-Nissen (1M) using the reaction with trinitrobenzenesulfonic acid. Peptides and proteins have been separated by HPLC by Hancock et al. using hydrophobic ionpairing of amino groups (38M),and cationic reagents (39M) to improve separation. Low molecular weight peptides have been se arated by Kitamura et al. (56M) by gel electrophoresis on an JDS polyacrylamide gel containing urea using fluran as a fluorescent reagent. Blackburn (6M) has edited the second edition of “Amino Acid Determinations”, and Niederwieser et al. (81M) have issued “New Techniques in Amino Acid, Peptide and Protein Analysis”. HPLC has been applied by Hurst et al. (50M) to the determination of free amino acids in cocoa beans after the
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formation of the o-phthaldehyde derivatives and by Wilkinson (122M) to the separation of dansyl amino acids using reversed-phase chromatography. Elution characteristics of amino acids on a cation-exchange resin have been studied by Harada et al. ( 4 0 as a means of separation from other food components. Preparation of isopropyl esters for GLC of amino acids has been studied by Frank et al. (27M) and the use of acetyl chloride in isopro yl alcohol recommended. Derivatization to the correspongng N-heptafluorobutyryl isopropyl esters has been described by Golan et al. (32M) before quantitative gas chromatography. A similar derivatization for preparation of isobutyl or propyl esters has been applied by de Lange et al. (62M) to the GLC analysis of the amino acids of milk protein and best results obtained with the isobutyl esters. Free amino acids in citrus juices have been determined by Licandro et al. (63M) after butylation and trifluoroacetylation by GLC on capillary columns with temerature programming. Optimum resin columns, flow rates, guffers, and temperature have been determined by Vratny et al. (118M)for the analysis of ninhydrin-positive substances in plant extracts. GLC analysis and ion-exchange analysis of amino acids have been compared by Tajima et al. (109M) and results are generally similar. Careful control of hydrolysis conditions has been found by Dove et al. (2lM to be necessary for the precise and accurate amino acid analysis of cow whole milk powders, separate performic acid peroxidations were found necessary for the determination of sulphur-containin amino acids. Peptides and a-amino acids have been separatei by Rothenbuehler et al. (93M) on cop er-Sephadex column. Amines and amino acids have been ifentified by Murray et al. (77M) by field-desorption mass spectrometry of their fluorescamine derivatives. Betaine in sugar-beet products has been determined by Steinle et al. (106M) by HPLC on a Nucleosil-NH2 column. Cysteine and glutathione in fruits have been determined by Saetre et al. (96mby HPLC on a cation exchange resin with electrochemical detection. Glutathione has been determined in food by Sirko ( 1 0 0 by polarography in the presence of cobaltic chloride. Monosodium glutamate has been analyzed in soups by Conacher et al. (16M) by gas chromatography after extraction and derivatization. A potentiometric microbial sensor for glutamic acid has been described by Hikuma et al. (43M) which is selective, stable, and reproducible. Glycine and albumin have been determined by Braithwaite et al. (8M) by flow-injection analysis and the formation of a fluorescent derivative for detection. Faster hydrolysis, 2 h, using 70% perchloric acid, has been recommended by Arneth et al. (2M) before the determination of hydroxyproline in meat. A reference method for hydroxyproline in meat has been issued by the British Standards Institution (9M). The use of carbon-13 pulsed Fourier transform nuclear magnetic resonance for the determination of hydroxyproline in meat has been applied by O’Neil et al. (84M) to the analysis of collagen and meat. Total and available lysine have been determined by Peterson et al. (86M) by the use of HPLC by chromatographic separation of edinitrophenyllysine before hydrolysis and of didansyl lysine after hydrolysis. Free lysine after extraction was reacted with dansyl chloride and then analyzed by HPLC by Warthesen et al. (12OM). Near-infrared reflectance has been used by Rubenthaler et al. (95M) to estimate lysine in cereals; monitoring with a reference method is necessary for consistent results. Gas chromatographic determination of available lysine has been described by Nair et al. (78M) after conversion to homoarginine and then to the N-trifluoroacetyl derivative of ita butyl ester. Enzyme analysis for L-lysine has been described by Skogber et al. ( I O I M ) using an electrode prepared with immobilized &sine decarboxylaseand by White et al. (121M) using the same enzyme on a carbon dioxide probe. Semiautomated enzyme procedures for lysine have been described by McBee et. al. (71M) and Roy (94M). Treatment of a carbohydrate-rich sample with hy ochlorite has been found by Hall et al. (37M) to prevent cargohydrate interference with lysine determination. The 2,4,6-trinitrobenzenesulfonic acid method for lysine has been studied by Kan et al. (53M) who have modified the hydrolysis step. Hol uin et al. (45M) have investi ated several methods for av&ble lysine and conclude that t i e dinitrobenzenesulfonate method is the simplest and quickest and provides reasonable accuracy. The use of L-lysine 6-aminotransferase in the
FOOD
resence of sodium 2,oxoglutarate and pyridoxal phosphate f a s been found by Soda et al. (102M) to provide a spectrohotometric determination of L-lysine. Reactive lysine in foods f a s been measured by Hurrell et al. (49M) by determining the dye binding capacity with Acid Orange 12 before and after reaction with propionic anhydride to block the lysine. Lysine, lysinoalanine, furosine, and pyridosine have been determined by Erbersdobler et al. (22M) in foods with an automatic amino acid analyzer and a single column, four-buffer, three-temperature program. Two methods for lysinoalanine have been compared by Haagsnia et al. (35M), and in general column amino acid analysis and TLC analysis give results in good agreement with each other. Lysinoalanine has been determined by Raymond (91M) on an amino acid analyzer and applied to food products; different temperatures for different products were found necessary to achieve separation. TLC for lysinoalanine has been studied by Haagsma et al. (36W and conditions for hydrolysis, chromatography, and densitometry were established. A gas chromatographic procedure has been developed by Hasegawa (41pR for the analysis of lysinoalanine in alkali treated food products. Free methionine in food products has been determined by O’Keefeet al. (83M) using HPLC after darisyl chloride treatment of a protein-free extract. A methionine-selective enzyme electrode has been prepared by Fung et al. (29M) by coating immobilized methionine lyase on an ammonia-sensingelectrode. Methionine, histidine, and tryptophan have been determined photometrically by Gayte et al. (30M) on basic hydrolysates. An automated colorimetric method for methionine using an iodoplatinate method has been applied by Njaa (82M) to the analysis of fish meals. S-Meth lcysteine sulfoxide in the presence of other amino acids has Keen determined by Howard et al. (47M) by TLC. An automatic amino acid analyzer has been used by Kovacheva (58M) to determine s-methylmethionine in plant products. The 3-methylhistidine content of meat has been determined by Poulter et al. (89M) using l-fluoro-2,4-dinitrobenzene, and concentrations in beef and pork are tabulated. Trypto han in cereal and legume samples has been determinedy! Piombo et al. (87M) using an automatic colorimetric method p-dimethylaminobenzaldehyde, and sodium nitrite. The fluorescence of the alkaline hydrolysate in the presence of formaldehyde has been used by Steinhart (105M) as a means of measuriing tryptophan in foods. A separation technique has also been proposed by Steinhart (104M)which measures fluorescence of the tryptophan-containing fraction after ion exchange Chromatography. Spectrophotometric and HPLC methods for tryptophan after pronase hydrolysis have been compared by De Vries et al. (19M) and the HPLC method supplies better quantitation. Tryptophan and tyrosine metabolites in the banana have been identified and quantified by Kenyhercz et al. (54M) by TLC and HPLC with electrochemical detection. A review of sulfhydryl and disulfide groups in meats including methods has been published by Hofmann et al. (44M). Sulfur-containing amino acids have been determined by Vardi et al. (115M) using ion-exchange thin-layer chromatography, and the method was applied to soya beans, peas, and lentils. Disulfide bonds and sulfhydryl groups in storage proteins of wheat have been determined by Bogdanov et al. (7M) by a modified Ellman method. Ammonium ion has been detected by Muroski et al. (7614 at a limit of 1pg/mL by evolution of ammonia and ultraviolet absorption spectrometry in the gas phase, Methods for the determination of the ammonia content of caseins, caseinates, and coprecipitates have been discussed by Mrowetz et al. using chloramine-T and phenol (75M) and Nessler reagent (73M) and applied to ammonium caseinates (74M). Hexosamines have been determined by gas chromatography by Hlonda et al. (46M) by se uential derivatization and trimethylsilylation and by ]Del V2le et al. (18M) on a two-column systlam in an amino acid analyzer which separates anomers of glucosamine and galactosamine. Biogenic amines have been separated by Pongor et al. (88M) by thin-layer ion exchange Chromatography and video-densitometry. Extraction and thin-layer chromatographic methods for biogenic amines in foods have been evaluated by Voigt et al. (117M) and best extraction and best solvent systems selected. HPLC has been used by Schmidtlein (97M) for the determination of biogenic amines in sardines and tuna; chromatography was carried out on dansylated amines.
Histamine has been determined in wines and musts by Subden et al. (107M) using HPLC after Sep Pak cleanup and phthaldehyde treatment and by Battaglia (3M)by HPLC after treatment with dansyl chloride. Fluorometry with phthalaldehyde has been applied by Taylor et al. (111M) to the determination of histamine in foods after extraction, and Chambers et al. (13M) have applied the AOAC fluorometric method for histamine in wine to the determination of histamine in cheese and confirmed the results by HPLC. Histamine methods using TLC have been described by Lieber et al. for tuna fish (64M) and for food extracts (65M). Kinetic and identification problems of the trimethylsilylated derivatives of tryptamine and 5-hydroxytryptamine have been investigated by Martinez et al. (69M) and techniques for obtaining the fully silylated derivative determined. Tyramine, phenethylamine, and tryptamine have been determined in sausage, cheese, and chocolate by Koehler et al. (57M) using HPLC after extraction with 0.1 N perchloric acid and clarification by centrifugation at 10OOOg. Tyramine has been determined by Daisley et al. (17M) in soups by GLC of the trifluoroacetate. Tyramine has also been determined in wine by Rivas Gonzalo et al. (92M) using spectro hotometric determination and TLC identification. H P L 8 has been used by Folstar et al. (26M) for the analysis of NB-alkanoyl-6hydroxytryptamines in the wax of reen coffee beans after purification by polyamide column c romatography. An automatic emission s ectrometer has been applied by Goulden et al. (33M) to the Xetermination of nitrogen-15 after Kjeldahl digestion and distillation and combustion of the ammonia produced. Amadori compounds have geen separated b HPLC from model systems by Takeoka et al. (11OM) bot{ with and without derivatization. Cytokinins in plant tissue have been determined by Summons et al. (108M) by directprobe mass spectrometry with the use of deuterium labeled standards and by Hashizume et al. (42M) also by gas chromatography-mass spectrometry of the trimethylsilyl derivatives. Nucleotides in foods have been determined by Fukuba et al. (28M) by isotachoelectrophoresis, using chloride as a leading anion and caproate anion as a terminal anion. Creatinine in meat extracts has been determined by Battaglia ( 4 M ) by HPLC of the hydrolyzed and clarified food. Methylated uric acids in crude caffeine have been detected by Citroreksoko et al. (14M)by ion-exchange separation and TLC. An automated method for caffeine has been developed by Fabre et al. (24M) by using a Technicon apparatus with dialysis. HPLC for caffeine in foods has been described by Juergens et al. (52M);sample preparation requires magnesium oxide extraction for caffeine and theobromine in cocoa and chocolate products by Kreiser et al. (59M) after defatting and extraction in water. Caffeine and trigonelline in coffee and tea have been determined by Van Duijn et al. (114M) by HPLC on an aqueous extract after clarification on an ion exchange column. Adenine, caffeine, theobromine, and theophylline have been determined in black tea by liquid chromatography on Dowex 50WX8 by Hsu et al. (48M). Xanthines have been chromatographed by Walton et al. (119M)on the cation-exchange resin Aminex 50W-X4. Caffeine has been titrated by acetic acid-perchloric acid in a nonaqueous system using potentiometric and conductometric titration by Matsumoto et al. (70M). Theobromine and caffeine have been separated on TLC by Mizuki et al. (72M) and measured by UV densitometry. A collaborative study carried out by Newton (80M) has confirmed the UV s ectrophotometric method for caffeine in coffee. A methof for caffeine in various matrices has been proposed by QuijanoRico et al. (9OM) which precipitates the caffeine as the hydroiodide and then separates the caffeine by pyrohydrolysis. Caffeine in coffee, tea, and soft drinks has been determined by Sontag et al. (130M) by differential pulse voltammetry after clarification on polyamide using a vitreous-carbon electrode at pH 1.2. Methods of analysis for potato glycoalkaloidshave been discussed by Maga (67M) in a review article. Bushway et al. (11M) have reported on the analysis of potato glycoalkaloids by HPLC; a-chaconine and a-solanine were detected and quantitated. TLC has been used by Cadle ( I O M ) to determine potato glycoalkaloids using an a-solanine standard, and a rapid method for total solanine has been described by Marihart et al. (68M)using extraction with ethanol-acetic acid and TLC. A further assay procedure for potato glycoalkaloids has been described by Vallejo et al. (113M) using radioim-
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munoassay. (See Carbohydrate Section for other articles on glycoalkaloids.)
VITAMINS Of the many and varied methods for the determination of vitamins in foods we have attempted to choose those using either new methods or improved variants of old methods. A review of developments in the determination of vitamins A, B, C, D, E, and K in foods has been published by Christie (13N). Vitamin A palmitate in margarines has been determined by HPLC by Aitzetmueller et al. (2N) using preliminary cleanup on sodium sulfate and sodium chloride, by Thompson et al. (68N) who measure the retin 1 palmitate and B carotene directly on a hexane extract, and gy Landen et al. (38N) who use high-pressure gel permeation chromatography for fractionation of the vitamin A active compounds followed by high-pressure reverse-phase chromatography for the separation of retinyl palmitate and 0-carotene. The same author (37N) has applied the technique to the analysis of retinyl palmitate in fortified cereals. A modified method for the determination of vitamin A and carotene in margarine and butter has been studied collaboratively by Parrish (53N) as well as the use of trifluoroacetic acid for color development and both have been found satisfactory. Absorbance measurement of the color produced by the treatment of vitamin A, from oils and fats, with 50 % trichloroacetic acid in methylene chloride has been described by Kamangar et al. (31N). The fluorometric determination of vitamin A in milk has been automated by Thompson et al. (69N) using conventional automatic equi ment. Provitamin A carotenes in tomatoes have been termined by Zakaria et al. ( 8 I N ) by the use of HPLC; a- and 0-carotene and lycopene were separated. A review of the methods for the determination of vitamin D in foods has been issued by Parrish (52N). The use of HPLC for the determination of vitamin D has been described by Nabholz et al. (50N) for dietetic products applyin HPLC to the unsaponifiable matter, by Henderson et al. &6N) to fortified milk after saponification and alumina column cleanup, by Cohen et al. (14N) to nonfat dried milk after methylene chloride extraction and Sep-Pak and Partisil-10 PAC cleanup. Vitamin D3 (25-hydroxycholecalciferol) has been determined by Koshy et al. (35N) in cow's milk by reversed-phase HPLC after extraction and chromatography on silica gel and a diatomaceous earth, and in chicken egg yolks (36N) after a sequential cleanup on silica gel, Partisil20, and Celite 545, Special cleanup procedures applicable to the determination of D vitamins in feeding stuffs by HPLC have been described by Knapstein et al. (33N) including both column chromatography and TLC. Vitamin D and 7dehydrocholesterol have been identified in cow m i h by gas chromatography-mass spectrometry and quantified by HPLC by Adachi et al. ( I N ) after rigorous cleanup of the unsaponifiable fraction. Vitamin D in dietetic foods, particularly infant foods, has been determined by Meine (46N) using four cleanup enrichment steps, TLC chromatography, and reflectance spectroscopy. Antila et al. (5") have proposed a method for water-soluble vitamin D in the aqueous phase of milk using solvolysis followed by TLC and colorimetry with antimony trichloride. A color reaction of vitamin D (calciferol) with tetrachloroethane in a medium of 11M #IC1 has been described by Hassan (24N);the yellow color obeys Beer's law in the range 3MOO pg/mL, and retinol does not interfere. Parrish (54N) has reviewed methods for vitamin E in foods. Tocopherols in vegetable oils have been determined by HPLC by Carpenter (12") by direct analysis after solution in the mobile phase, by Pickston (56N) after saponification and ether extraction, and by Hung et al. (29N) in fish liver without saponification. An HPLC separation of a-, 0-, y-, and &toco herols has been proposed by Tangney et al. (66N) proviiing separation in 12 min on a Spherisorb column. Individual tocopherols in fat have been determined by Conte et al. (15N) usin gas chromatography after TLC of the unsaponifiables. $LC-GC has also been used by Meijboom et al. (45N) for tocopherols in unsaponifiables of palm oil. Mordet et al. (47N) have also applied TLC-GC to the determination of tocopherols using capillary column GC. Saponification, silica column cleanup, TLC se aration, and colorimetry have been suggested by Manz et a[ (42N) for the determination of a-tocopherol in foods and feeding-stuffs. Differential pulse polarography has been investigated by Podlaha et al. (57N)
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for the determination of tocopherols in vegetable oils and compared with HPLC, the authors conclude that the HPLC method gives better separation. Another study by Deldime et al. (I6W on the use of differential pulse polarography has indicated that this technique is useful for the determination of a-tocopherol in oils. Polarography has also been used by Kobori et al. (34N) to determine vitamins K, and KB,the addition of cysteine was found necessary to se arate the half-wave potentials of the two vitamins to provite simultaneous detection. Phytonadione has also been determined by Horn (28N) after petroleum ether extraction and silica gel and TLC separation with detection by spectrophotodensitometry, Seifert (64N) has determined vitamin K1in given leafy vegetables by gas chromatography after extraction and alumina column chromatography. HPLC lends itself to simultaneous determination of a mixture of vitamins. In the field of fat soluble vitamins Henderson et al. (25N) have reported on the determination of vitamins A and D in milks on a V dac TP reverse-phase C18 column. Soderhjelm et al. ( 6 5 d have re orted on the determination of vitamins A and E by reversexphase HPLC after saponification, and DeVries et al. (17N) have described a similar technique for the same vitamins from breakfast cereal. Widicus et al. (78N) have developed a method, which does not use saponification, for these vitamins in cereal products. Another method has been proposed by Mankel (4IN) for vitamins A, D2, and D3 as well as tocopherols and 6-carotene and applied to margarines and dietetic foods. The vitamins A, D, and E have been determined by Antalick (4N) by HPLC after saponification. Tocopherols and vitamin K in foods have been analyzed by Thompson et al. (67N) after extraction by HPLC; vitamin K determination re uired preliminary clarification on a preparative HPLC c3umn. Reversed-phaseHPLC on two Zorbax ODS columns has been used by Barnett et al. (6N) to determine vitamins A, D2 or D3,E, and K in infant formulas and dairy products after enzymatic hydrolysis of the lipids. A scheme for simultaneous and parallel determinations of vitamins A, D, and E in dietetic foods has been devised by Bellamonte et al. (8N) using GC for the tocopherols, colorimetry with glyceryl dichlorohydrin for the retinol, and the determination of D vitamin by GC after TLC separation. Methods for thiamine include oxidation with cyanogen bromide to thiochrome after extraction, clarase digestion, and column purification proposed by Rettenmaler et al. (6IN). The use of cysteine has been proposed by Pickova (55N) to displace thiamine from protein complexes. Differential pulse polarography has been shown by Kishore et al. (32N) to be useful for the assay of thiamine at the micromolar level. Riboflavin has been determined by Rashid et al. (59N) in milk by fluorometry after lead acetate clarification. Egberg (21N) has conducted a collaborative study comparing a semiautomated riboflavin procedure with the standard manual procedure, and results compared favorably. Several methods for vitamin B com onents have been developed using HPLC. ~ i et m al. ( 3 9 ~ ) ave reported on the use of a Spherisorb ODS column, Wong (80N) has used a Zi ax SCX column after enzyme extraction and ion-exchangec eanup, and Vanderslice et al. (73N) have separated B6 vitamers and pyridoxic acid on a Bio-Rad A-25 resin column at 55 "C. Extraction with sulfosalicylic acid has been suggested by Vanderslice et al. (72N) before HPLC determination, and Gregory (23N) has compared HPLC results with microbiologicalresults, and the LC procedure was found to be less subject to interferences. Two separation techniques usin HPLC have been described for cobalamins by Frankel et al. (%2A9,including reverse-phase HPLC and gradient elution. Total separation of cobalamins and coenzyme B12has been achieved by Mowot et al. (48N) by HPLC with gradient elution with methanol in 0.05% sulfuric acid, Two radioassays for cyanocobalamin have been compared by Beck (7N) on seafoods, a rigorous extraction procedure was found necessary to ensure reproducibility. Fish sera have been found by Itakissios et al. (30N) to provide high bindin capacity for vitamin B12and therefore to be useful as bincfing proteins for the radioassay of the vitamin. Niacin has been determined by Tyler et al. (7IN) in cereal samples by the use of HPLC after extraction with calcium hydroxide, column cleanup, and permanganate treatment. A semiautomated method for niacin and niacinamide has been submitted by Egberg ( 2 0 to collaborative study, the results
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compare favorably with those obtained by both the microbiological and colorimetric methods. Choline has been determined in soya-bean meal by Dorsey et al. (18N) by the use of liquid chromatography and an ion.exchange membrane detector after hydrolysis and ammonium reineckate precipitation. A review of methods for the determination of biotin and choline has been published by Wilson et al. (79N). Radioassay and microbiological assay of folate levels in foods have been studied by Ruddiick et al. (63N),and while the radioassay procedure is faster, both methods are only suitable for measuring that form of folate used as standard. Folate derivatives have been separated by paired-ion HPLC by Reingold et al. (60N) using a precolumn and a two-phase system. Systems for multiple water-soluble vitamin determinations include the determination of thiamine and riboflavin in meat products by HPLC dlescribed by Ang et al. (3N) using fluorometric detection, the analysis of some water soluble vitamins in cereal grains also by HPLC proposed by Mauro (44N), HPLC analysis for ascorbic acid and riboflavin in citrus juices using UV and fluorometric detection proposed by Rouseff (62N), and HPLC analysis of B vitamins in rice and rice products described by Toma et al. (70N). Ascorbic acid in fruit juices has been determined by Posadka et al. (58N) wihh an immobilized ascorbate oxidase enzyme attached to a Clark oxygen amperometric electrode. Immobilized ascorbate oxidase has been used by List (40N) to determine ascorbic acid photometri~cally. A comparison of two automated fluorometric determinations for vitamin C in foods and the manual method has been obtained by Dunmire et al. (19N),both methods agreed well with the manual AOAC method. Potassium hexacyancferrate(II1) has been used by Muralikrishna et al. (49N)for the titration of ascorbic acid in acetic acid and sulfuric acid with diphenylamine indicator. Beutler et al. (9“) have based a method for ascorbic acid on its oxidation to dehydroascorbic acid by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide in the presence of ascorbate oxidase with colorimetric measurement of the formazan formled. Formazan formed by the reaction of titranitrotetrazoliuxn blue chloride with ascorbic acid has been used by Vasileva-Aleksandrova et al. (74N) to measure ascorbic acid. Man iindicators for the titration of ascorbic acid with cerium(1Vfhave been shown by Verma et al. (75N) to be useful, among them are crystal violet, methyl red, malachite green, and methylene blue. Stopped-flow methods for ascorbic acid have been described by Hiromi et al. (27N) and applied to the determination of ascorbic acid in orange juice, by Obata et al. (51N),the method eliminates interference from triose reductone. Vitamin C in milk has been determined byMatthiemen (43N) by direct evaluation of the thin-layer chromatogram of the hydrazone. HPLC has been used by Bui-Nguyen ( I O N ) to tieparate ascorbic acid from isoascorbic acid and applied to fruit juices. Bunton et al. ( I I N ) have described the determination of ascorbic and erythorbic acids in meat products by TLC. Voigt et al. (76N, 77N) have discussed and com ared the microbiological, chemical, and protozoan m e t h o g for vitamin analysis, the protozoan methods are slow but are believed to provide a more accurate measure of biologically available vitamins.
MISCELLANEOUS The references in this section cover review articles and books on techniques applied to a variety of foods. The great interest in HPLC has ]prompted many reviews and books on the use of this technique in food analysis. Charalambous (8P) has edited the proceedings of a symposium on the analysis of foods and bevera es by HPLC. Reviews of these applications have been pubfished by Macrae (17‘P) and Saxby (22P). Adams et al. UP)have reviewed selected uses of HPLC for the separation of natural products. Pryde et al. (ZIP) have published a book on the applications of HPLC. Automatic methods applicable to food analysis have been reviewed by Stockwell (25P)and “Topics in Automatic Analysis”, edited includes articles on automatic reaction by Foreman et al. (11P), rate methods and the analysis of water-soluble vitamins. The use of gas Chromatography in food analysis has been reviewed by Manning (38P)and Dickes (IOP).Applications of mass spectrometry iin food science have been discussed by Horman (12P). Applications of mass ripectrometry to the analysis and detection of food components such as fatty acids, carbohydrates, flavonoids,toxic residues etc. has been included
in biochemical applications of mass spectrometry by Waller et al. (26P). Fluorescence derivatization, including the preparation of derivatives for analytical purposes, has been reviewed by Seitz (23P)and derivatization techniques for use with HPLC fluorescent detectors have been compiled by Lawrence (16P). Enzymic methods in food analysis have been reviewed by Wiseman (27P). McCormick et al. (19P) have discussed enzyme methods for vitamins and coenzymes including methods for cobalamins, tocopherols, vitamins K, A, and D. Performance specifications for infrared milk analyzers have been listed by Biggs (6P). The uses of isotachophoresis for the analysis of food products have been discussed by Kaiser et al. (13P).An account of the technique and current uses of flow-injection analysis has been reviewed by Betteridge (5P). Books have been published by Osborne et al. (20B) on the analysis of nutrients in foods and by Kirschner (14P)who has issued a second edition of his book on thin-layer chromatography and on analytical derivatization reactions by Knapp (15P).Voltammetric methods for the determination of food additives and dyes have been included by Smyth et al. (24P) in a review article. The Chemical Society (9P)has issued a report covering recommended general methods for the examination of fish and fish products. Papers of analytical interest on coffee have been included in the proceedings of the eighth international scientific colloquium on coffee (4P).
ACKNOWLEDGMENT The authors gratefully acknowledge the efforts of Martha Leggio and Jean Sullivan for typing and collating the manuscript. LITERATURE CITED ADDITIVES
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