Anal. Chem. 1983, 55, 164R-196R (F24) Varnell, D. F.; Runt, J. P.; Coleman, M. M. Macromolecules 1981, 14, 1350-1356. (F25) Aylward, N. N.; TI, S. S. J . Polym. Sci., folym. Phys. Ed. 1981, 19, 1805-18 16. (F26) Antoon, M. K.; Koenig, J. L.; Seraflnl, T. J. folym. Scl., folym. fhys. Ed. 1981, 19, 1567-1575. (F27) Stevens, G. C. J. Appl. Polym. Scl. 1981, 26, 4259-4278. (F28) Stevens, G. C. J. Appl. folym. Scl. 1981, 26, 4279-4297. (F29) Endrey, A. L. J. folym. Scl., folym. Chem. Ed. 1982, 2 0 , 2 105-21 16. (F30) Coleman, M. M.; Sivy, G. T. Carbon 1981, 19, 123-126. (F31) Sivy, G. T.; Coleman, M. M. Carbon 127-131. (F32) Coleman, M. M.; Slvy, G. T. Carbon 133-135. (F33) Slvy, G. T.; Coleman, M. M. Carbon 137-139. (F34) Gupta, M. K.; Bansil, R. J. folym. Scl., folym. fhys. Ed. 1981, 19, 353-360. (F35) Kim, C. S.;Dodge, A. L.; Lau. S.F.; Kawasaki, A. Anal. Chem. 1982, 5 4 , 232-236.
(G20) Schabron, J. F.; Bradfleld, D. 2 . Anal. Chim. Acta 1981, 129, 243-6. (G21) Schenk, C.; Kayen, A. H. M. Cong. FATIPEC 1980, 15, 345-360. (G22) Sidwell, J. A.; Wllllamson, A. G. Int. Rubber Conf. 1981, 1, C8.1C6.8. THERMAL ANALYSIS
(Hl) Belorgey, G.; Prud'Hommme, R. E. J. folym. Sci., Polym. Phys. Ed. 1982, 20, 191-203. (H2) Cardillo, P.;Casalini, A.; Galtlerl, A.; Vecchi, C.; Audlslo, G. Conv. Itai. Sci Macromol., 5th 1981, 249-51. (H3) Das, A. N.; Baijal, S. K. J. Appl. folym. Sci. 1982, 27, 211-23. (H4) England, J. C.; Long, R. E.; Townsend, D. J. Anal. Proc. 1981, 18, 430-7. (H5) Gilbert, M.; Vyvoda, J. C. Polymer 1981, 22, 1134-6. (H8) Glans, J. H.; Turner, D. T. Polymer 1981, 22, 1540-3. (H7) Klshore, K.; Santhanalakshmi, K. N. J. folym. Sci., Polym. Chem. Ed. 1981, 19, 2387-75. (H8) Nishizakl, H.; Yoshlda, K. J. Appl. Polym. Sci. 1981, 26, 3503-4. (H9) Ragosta, G.; Greco, R.; Martuscelll, E.; Sadocco, P.; Seves, A,; Vlclnl, L. Polymer 1982, 23, 466-72. (H10) Lockwood, R. J.; Alberlno, L. M. ACS Symp. Ser. 1981, No. 172 (Urethane Chem. Appl.) 363-72. (H11) Smith, W. A.; Barlow, J. W.; Paul, D. R. J. Appl. Polym. Scl. 1981, 26, 4233-45. (H12) Sebenlk, A.; Osredkar, U.; Zlgon, M.; Vizovlsek, I.Angew. Makromol. Chem. 1982, 102, 81-5. (H13) Turi, E. A., Ed. "Thermal Characterlzatlon of Polymeric Materlals"; Academic Press, New York, 1981. (H14) Ulukhanov. A. G.; Lapitskll, V. A,; Akutin, M. S.;Skokova, L. D. Plast. Massy 1981. 9 , 59. (H15) Walsh, D. J.; Higgins, J. S.; Zhikuan, C. Polymer 1982, 23, 336-9.
LI OUID CHROMATOQRAPHY
(GI) Afredson, T. Am. Lab. (FalrtleM, Conn.) 1981, 13, 44, 46-7, 49-51. (G2) Alfredson, T. Int. Lab. 1981, (Sept), 46, 48-50, 52-3. (G3) Andrews, G. D.; Vatvars, A. Macromolecules 1981, 14, 1603-5. (G4) Danlelewlcz, M.; Kubln, M. J. Appl. Polym. Sci. 1981, 26, 951-6. (G5) Edwards, D. J. H. HRC C C , J. High Resolut. Chromatogr. Chromatogr. Commun. 1982, 5 , 161-3. (G8) Eppert, G.; Llebscher, G.; Stief, C. J. Chrom8togr. 1982,238, 385-98. (G7) Fech, J.; De Wltt. A. f r o c . Int. Wire Cable Symp. 1980, 29th, 327-30. (G8) Furukawa, M.; Yokoyama, T. J. Chromatogr. 1980. 198, 212-16. (G9) Hagnauer, G. L.; Dunn, D. A. Nafl. S A M E Tech. Conf. 1980, 12, 648-55. (G10) Hagnauer, G. L. Ind. Res. Dev. 1981, 23, 128-33. (G11) Hagnauer, G. L.; Dunn, D. A. Ind. Eng. Chem. frod. Res. Dev. 1982, 21, 68-73. (G12) Haney, M. A.; Dark, W. A. J. Chromatogr. Scl. 1980, 18, 655-9. (G13) Hayashi, H. Nagano-ken Elsel Kogal Kenkyusho Kenkyu Kokoku 1981, 4 , 1-6. (G14) Juergens, U.; Doemllng, H. J. Dtsch. Lebensm.-Rundsch 1982, 78, 49-5 1. (G15) Knopp, H.; Tenner, R.; Truempler, G. SYSpurRep. 1981, 19, 163-7. (G16) Kroschwltz, H.; Niklas, 6.; Noack, R.; Tenner, R.; Truempler, G. 146, 290 (C1 C07C1191048), 04 Feb 1981. Appl. 215882, 28 Sept 1979. (G17) Schabron, J. F.; Smith, V. J.; Ware, J. L. J. Liq. Chromatogr. 1982, 5 , 613-24. (018) Schabron, J. F.; Bradfield, D. 2 . J. Appl. folym. Scl. 1981, 26, 2479-83. (G19) Schabron, J. F. J. Liq. Chromatogr. 1982, 5 , 1269-76.
MISCELLANEOUS TECHNIOUES
(11) Rose, W.; Meurer, C. frog. ColloidPolym. Sci. 1980, 6 7 , 167-9. (12) Merlin, A,; Lougnot, J.; Fouassier, J. P. Polym. Bull. 1980, 2 , 847-50. (13) Leahy, H. J., Jr.; Campbell, D. S. Surf. Interrace Anal. 1979, 1, 75-9. (14) Martin, M.; Reynaud, R. Anal. Chem. 1980, 52, 2293-8. (15) Raczek, J.; Meyerhoff, G. Macromolecules 1980, 13, 1251-3. (16) Friedrlch, C.; Laupretre, F.; Noel, C.; Monnerie, L. Macromolecules 1980, 13, 1625-8. (17) Van Houwellngen, G. D. B. Analyst (London) 1981, 106, 1057-70. (18) Igarashl, S. Mlzu Shod Gljutsu 1981, 22, 697-701. Chem. Abstr. 1981, 9 5 , 1917378. (19) Tutalkova, A.; Snuparek, J. Angew. Makromol. Chern. 1982, 103, 39-50. Chem. Abstr. 1982, 9 6 , 200675t. (110) Hajos, P.; Inczedy, J. J. Chromafogr. 1980, 201, 193-7. ( I l l ) Relgler, P. F.; Larson, J.; Bowman, L. J. folym. Sci., Polym. Chem. Ed. 1981, 19, 3247-55.
Food Arthur K. Foltr," James A. Yeransian, and Katherine G. Sloman General Foods Corporation, Central Research Department, White Plains, New York 10625
This review is focused on the time interval from October 1980, which was the end of our last report (24P),to October 1982. Once again, we have tried to preferentially cite domestic and the more widely circulated foreign journals over less accessible journals when work of a similar nature has been reported. Recent publications of possible interest to the food analytical chemist for general reference are the eighth edition of Pearson's Chemical Analysis of Foods (7P),Develo ments in Food Analysis Techniques-2 (17P),and the puhished proceedings of the first European Conference on Food Chemistry which dealt with recent developments in food analysis (4P). Available standard reference materials for use in the determination of nutrients and trace elements in plants and agricultural food products are given by Alvarez (2P)and standards for the analyst are also discussed by Watson (27P). The proceedings of a nutrient analysis symposium presented at the 93rd annual A.O.A.C. meeting have been published (25P)which described the state of the art for routine nutrient analysis of foods. A great deal of interest and activity have been noted in the development of methods which make use of near-infrared reflectance spectroscopy. These methods are rapid, lend themselves well to automation, and are often reported to be as accurate as the more conventional methods used for I64R
0003-2700/83/ 0355-1 64R3$06.50/0
standardization and comparison purposes. Allvin (1P) presents a review on uses of NIR in determining various food components and Kaffka (12P)describes the applications of computer-assisted NIR to measure the ripeness, total solids, and acid content of cherries, apricots, and plums, the amounts of protein and fat in pasta, the ethanol content of wine, and the quality of pork and beef. NIR techniques are also described for the determination of fat, protein, and carbohydrate content of cocoa powder (13P) as well as for the fat, protein, and water content of pasta products (15P)and cheese (9P). Osborne et al. (22P) report on the application of NIR for analyzing flour for protein, moisture, particle size, color, and starch damage. NIR has also been applied to the multicomponent analysis of meat products (5P, 6P)sunflower seeds (14P),and wheat, soybean, pork, and fresh potatoes (1IP). Shenk et al. (23P)have evaluated a NIR system for estimating the protein, in vitro dry matter disappearance, acid-detergent and neutral-detergent fiber, cellulose, and calcium, phosphorus, and potassium in forage and grain.
ADDITIVES Ion-pair liquid chromatographicmethods for food additives of various types were discussed by Cornet et al. (11A) in a chapter on chromatographic application. Faugere (14A) re0
1983 Amerlcan Chemical Soclety
FOOOS
(57A). Archer (3A) extracted a l l a h from oils with methanol before HPLC with 280-nm 8 V detection. Holley et al. (24A) measured sorbic acid in salami by an alternate wavelen h correction to the UV absorbance of an still had some spice interference. Naisooctane extract kayama et al. (48A) specified a DEGS/H,PO, GC column to avoid interference to sorbate in miso analysis. Other studies GOA) showed that ethyl oleate was the interferant in GC measurement. Fukasawa et al. (29A) adapted a wine-sorbic acid method to other foods that utilized UV absorbance after bromination. GC and colorimetric methods for processed cheeses were compared by It0 et al. (30A)who found that the AOAC thiobarbituric results came out high due to interferences. Werner et al. (67A) favored a steam distillation, UV scanning approach for analysis of low sorbate concentrations in cheese. Parks et al. (55A) methanol-extracted citrus peel to determine sorbate before cleanup and HPLC to achieve a 0.5 ppm detection limit. A part-per-million of sorbic acid in wine was detectable by using TLC on polyamide in work by Chretian et al. @A). A way to alleviate interferences to sorbic acid when applying the offical Japanese GC methqd to wines was published by Matsukawa et al. (45A). Sorbic and benzoic acids in drinks were simultaneously determined by HPLC. using a perchloric acid/2-propanol/water mobile phase by Collinge et al. (9A). HPLC conditions to optimize the separation of benzoic and sorbic acids from sauerkraut and liquid foods were given by Froehlich (Z6A). Horinopuchi et al. ( E A ) made use of dialysis before ether extraction and GC to analyze for sorbic acid and saccharin at the same time. Fang et al. (Z3A) varied tetramethylammonium salt concentrations to adjust their ion-pair HPLC separations of benzoate, sorbate. and saccharin. The trifluoroacetates or heptafluorobutyrates of gallates and hydroxybenzoates were prepared by Bajardi et al. (5A) methodology for preservatives in foods. Collinge found that gradient elution facilitated separations of sorbates, benzoates, salicylates, and hydroxybenzoates in mayonaise when using RP-18 columns. Hydroxybenzoate esters extracted from processed meats were quantified by direct HPLC of CH,CN extracts in work by Perfetti et al. (56A). Flores et al. (Z5A) effected a preliminary separation of preservatives from meat by the TAS technique before their TLC separations. Rubach et al. (60A) reported isotachophoretic preservative separations in less than 15 min on water extracts of baked goods. Galensa et al. (20A) formed benzoyl derivatives of phydroxybenzoic esters for normal and reversed-phase HPLC as well as GLC analysis of complex food matrices such as mustard. Benzoic and vanillic acids down to the low partsper-million level in soy sauce were measured by Kihara (%A) who cleaned up the sample solution with NaHCO,-MeCI2 partition before HPLC. Kitada et al. (36A) pursued ethyl ether extraction from soy sauce as preliminary separation before HPLC of saccharin, benzoic acid, and p-hydroxybenzoate esters. Different initial separations such as ether extraction and steam distillation were examined by Ogawa et al. (52A) in attempts to differentiate natural and added benzoates in ginseng tea and bamboo shoots. Results of collaboratively studying the Karasz methods for sulfites, benzoates, sorbates, ascorbates, and blood added to beef were reported by Maxstadt et al. (&A), with good agreement for all but the latter found. A headspace GC method using flame photometric detection for SO2 was employed by Hamano e t al. (23A) for various foods. Isshiki et al. (29A) reported their version of a direct injection GC method for propionic acid in bakery products. The p-nitrobenzyl derivative of propionates was formed by Takasuki et al. (64A) after water extraction and before GC measurement in a method for bakery goods. Bread was analyzed for bromate by Oikawa et al. 6 4 A ) using suppressed ion chromatography with a borate buffer. Allylamine traces from allyl isothiocyanate decomposition were visualized by fluorescence of its dansyl derivative after TLC separation in a paper by Kostyukovskii et al. (37A). Burkhardt (7A)gave a qualitative test for 3-(5-nitro-2-furyl)acrylic acid in wines using absorbance at 365 nm after removing phenolics with PVP from red wine. An AOAC method was modified by DeSiena et al. (ZZA) to function better a t low nitrite levels in fabricated foods. Suzuki et al. (31A)utilized ion exchange isolation before electrophoresis of EDTA as an iron complex.
ct
compbr i;c and LC' peak ribs stored on Organlrslional acliv~les are ACS. ASTM. E-19,and AOAC.
dlsk.
viewed HPLC methods for food preservatives. A multitechnique procedure for elucidating types of antioxidants in oils using TLC, column chromatography. and TMSGC was given by Nakazoto et al. (49A). Van Peterghem et al. (65A) used a n elaborate TLC method with three solvent systems and two adsorbants to separate 11 fat antioxidants. Wyatt (68A) studied the precision of his CH,CN extraction-GC method for oil antioxidants over a 2-week span. Min et al. (47A) employed a setup to sweep off antioxidants that they had assembled earlier for volatile flavor compounds in oil which involved trapping on the demounted GC column. Fry (Z7A) showed that conversion of TBHC),to tprt-hutvlnuinone WRS the cause of low recoveries in GC analysis. Austin et al. (4Aj analyzed TRHQ by GC after CH,CN extraction hy cnnverting it t o the TMS derivative. R H A and R H T were measured down to microgram levels by Maruyama et al. (43A) who converted the latter to a cresol before reacting both to heptanuorobutyric esters for EC GC. Masoud et al. ( M A )applied fluorescence, UV, and electrochemical detection to antioxidant species separated by isocratic HPLC. Brieskorn et al. (6A) found a twofold increase in sensitivity possible by determining phenolic antioxidants and tocopherols with a rotating glassy carbon voltammetric instrument. Sakurai et al. (6ZA) determined BHA and BHT in fish by pentaneCH,CN partition, Florisil cleanup, and GC separation. Spark (62A) used alumina columns with UV detection and colorimetric tests for methods fast enough to detect ethoxyquin in fish meal in a factory environment. Ethoxyquin at below 100 ppm was found in spices by using reversed-phase HPLC by Perfette et al. ~
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ANALYTICAL CHEMISTRY. VOL. 55. NO. 5, APRIL 1983
i0SR
FOODS
Methods using GC for examination of emulsifier composition were reviewed by Haken (22A). A staged procedure for systematically detecting emulsifier additives not allowed in Switzerland was published by Martin et al. (42A) who employed column, thin-layer, and gas chromatographic separations. Thin-layer methods for 19 different emulsifiers were studied collaboratively by Martin (41A). Ethoxylated monoglycerides in bread were measured gravimetrically by Lawrence et al. (40A) after precipitation with Ba2+ and phosphomolybdate. Inoue et al. (28A)separated the tartaric trimethylsilyl compound by GC to determine diacetyl tartaric esters added to coffee creamers. Normal phase HPLC separation allowed Hurst et al. (26A) to quantify lecithin in chocolate after CHC13 extraction and Sep-PAK cleanup. Kundu (39A)reported being able to detect 2 pg of silicone oil in vegetable oil by silica gel TLC. The methylation of saccharin with diazomethane was studied by Ishikawa et al. (70A)who gave conditions to control the ratios of N-methyl and 0-methyl derivatives. Takatsuki et al. (63A) methylated saccharin with CH31 and a phase transfer catalyst to avoid diazomethane hazards. Noda et al. (51A)analyzed milk products for saccharin by flame photometric GC after dialysis, solvent extraction, and methylation. An amino acid analyzer permitted Vesely et al. (66A) to methyl ester (APM) in measure L-a-aspartyl-L-phenylalanine drinks down to 20 nmol. Prude1 et al. (59A)determined Usal (APM HC1) in dairy products with a modified amino acid analyzer instrument. Grosspietsch et al. (21A) found they could directly inject fiitered water extracts of foods onto a (2-18 HPLC column to determine acesulfam-K with tetrabutylammonium HS04 present in MeOH/HzO mobile phase. Kenndler et al. (34A)employed isotachophoresis to measure glutamate, guanosine 5’-monophosphate, and inosine 5’monophosphate in food aqueous extracts. A fluorimetric measurement of monosodium glutamate following fluorescamine reaction was used by Ang et al. (2A)for noodle and snack analysis. Kato (33A)separated glycyrrhizinate from tartrazine and p-hydroxybenzoate in foods by HPLC on a Zipax SAX column and 254-nm UV detection. Yamada et al. (69A) monitored their HPLC effluent at 250 nm for reversed-phase HPLC of glycyrrhizinic acid. Ethyl vanillin in chocolate and syrup was extracted with water ethanol/acetic acid before HPLC separation by Hurst et a[ (27A). Postal et al. (58A)
quinine from drinks and drugs with results that agreed with fluorometric methods. Coatings of coumarone-indene resin on citrus fruits were determined down to trace amounts with two-development TLC in a paper by Fujinuma et al. (18A). Iwaida et al. (32A)analyzed beverages for added taurine using an ion exchange column and 1% H3P0 mobile phase. The presence of caramel color was affirmediy measuring 5-(hydroxymethyl)-2-furaldehydein a mixture of various flavoring materials and ingredients by Alfonso et al. ( I A ) .
ADULTERATION, CONTAMINATION, DECOMPOSITION The use of GLC separations to elucidate adulteration of fats and oils was reviewed by Prada Rodriguez et al. (164B). Gegiou et al. (73B)analyzed oils for the 2-position fatty acid to detect reesterification. Fincke (62B) discussed the limitations of triglyceride analysis to detect cocoa butter adulteration. Glyceryl ethers, separated as unsaponifiable matter, were used by Wijsman et al. (232B) to find beef fat in pork fat. Several workers applied different techniques to detect fatty acid anilides and aniline in edible oils mixed with denatured oil. Wheals et al. (229B)separated unusual components by SEC before TLC, IR,and MS identification. Luckas et al. (133B)monitored GC fatty acid separations for unusual peaks and also separated aniline and anilides by HPLC. Stahl et al. (197B) employed a TAS procedure to transfer aniline to a TLC plate and then reacted it with fluorescamine. Vioque et al. (222B) visualized their TLC separations with p-dimethylaminocinnamaldehyde. Jeuring et al. (111B) used electron capture GC for 2,4,6-tribromoaniline after saponification and bromination of anilides. The adulterant maleic 166R
ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
anhydride was made detectable in olive oil by Amelotti et al. (7B)using a colorimetric test. Sengupta et al. (19OB)could detect oxalic acid in oil by reducing it to glycolic acid and developing a color with phenylhydrazinium chloride. Adulterated peanut oil was shown to contain cyclopropenoic or cyclopropanoicfatty acids by Bianchini et al. (17B)using capillary GC of methyl esters. The denaturant denatonium benzoate was detectable in rapeseed oil when Damon et al. (48B) separated it on a bonded-cyano HPLC column. Carbon-13 to carbon-12 ratios were studied by Bricout et al. (25B) of vanillin isolated from natural vanilla and synthetic sources to assess adulteration. Juergens (113B)separated vanillin and 4-hydroxybenzoic acid by HPLC to evaluate their ratio as an authenticity marker. y-Lactones along with vanillin were found in enhanced coconut flavor vs. only 6 in an investigation by Pflannhauser et al. (162B). Petrus et al. (160B) reviewed methods to detect citrus oil and juice adulteration. Wild et al. (231B)detected Tagetes extracts in orange oil by HPLC separation of xanthophyll diesters. A TLC method for toxic muscarine and muscimol from poisonous mushrooms mixed with edible ones was published by Stijve (199B). Large amounts of work still appear on developing and refining methodology for food mycotoxins. Honvitz et al. (101B) discussed the considerations necessary for quality assurance in trace analysis for food contaminants and toxins. The IUPAC (107B) reviewed methods for mycotoxin analysis with emphasis on feeds. Crosby (46B)reviewed cleanup procedures applicable to dyes, mycotoxins, and polycyclic aromatic hydrocarbons. Literature from 1965 to 1980 was reviewed by Lee et al. (128B)that dealt with TLC methods for 17 mycotoxins. Levi (131B)discussed studies on the likelihood and analysis of mycotoxins in coffee. Stoloff (200B) reviewed methods for many toxins in foods. Weber (226B) covered mycotoxin methodology based on TLC and HPLC separations. Minicolumn techniques for screening for mycotoxins were listed by Holaday (93B). Issaq et al. (108B)listed aflatoxin Bl! Bz, G1, and Gz separation conditions on six commercial silica gel plates. The advantages of homogeneity and solvent economy were stated by Whitaker et al. (230B)who favored a water slurry method of extracting aflatoxin from peanuts. Cohen et al. (43B)separated TFA reaction products of aflatoxins extracted from corn and feeds with fluorescence HPLC. Davis et al. (49B)gave modifications to the fluorimetric-iodine method for screening for B,. A comparison of HPLC and CD methods for aflatoxins in corn and nuts led DeVries et al. (52B) to consider the former (TFA-HPLC) equivalent. A micro-ELISA (enzyme linked immunosorbent assay) was reported by Biermann et al. (18B)to be rapid for B1 in food. El-Nakib et al. (58B)had earlier studied ELISA and compared it to a solid phase RIA, finding the former more reliable for B,. Brumley et al. (28B)confirmed aflatoxins B1 and M1 by negative-ion chemical ionization MS. Francis et al. (63B)gave their HPLC procedure for B1, Bz, G1, and Gz that monitored fluorescence in a silica gel packed cell after a normal-phase silica column separation. Friesen et al. (67B)had data from a check sample program that showed no significant differences between BF, CB, EEC, and HPLC methods for aflatoxins in peanut meal and corn meal. Shotwell et al. (192B)evaluated the Holaday-Velasco and modified Holaday minicolumn methods and found the former superior for peanuts, producing no false positives. McKinney (139B)employed a silica SepPAK as a first stage cleanup of a toluene-CH&N solution of cottonseed extract and then went to minicolumn, TLC, or HPLC measurement. Haghighi et al. (83B)analyzed pistachio nuts for Bl and G1 by HPLC separation of their TFA-produced fluorescent derivatives. A method for spices by Awe et al. (13B) used a 10-pm silica gel HPLC column and a silica-packed fluorescence flowcell. Wei et al. (227B)used HPLC separation after Sep-PAK and TLC cleanups for aflatoxins in soy sauce but found them unstable in that food. A comparison of methods led Trucksess et al. (212B)to consider the AOAC cottonseed and ginger ones suitable for sunflower seed meal, but not the peanut method. Stubblefield et al. (201B) investigated aflatoxin measurement in animal tissues and found that two-dimensional TLC (AOAC 26.A14C) gave good recoveries. Hurst et al. (105B)deliberately contaminated cocoa beans to test methodology for B1, GI, Bz,and Gz that used reversed-phase HPLC, with UV and fluorescence detection. A composite method for six mycotoxins based on HPLC was described by Chaytor (38B)that could detect 1ng of each
FOODS
per injection. Roberts et al. (17OB)scaled down the EEC method for B1 using TLC and found that it was applicable to ochratoxin A analysis for simple samples. Kleinau (120B) discussed BF, derivatization of ochratoxin A directly on TLC plates. The electrochemicalbehavior of trichothecene toxins was related to the unsaturated a,p keto group by Palmisano et al. (166B) who measured deoxynivalenol (Vomitoxin) by DPP and also GC (after silanization). Sano et al. (17RB) reacted trichotheceneswith nicotinamide and %acetylpyridine to measure them fluorimetrically on TLC plates. Scott et al. (184B) detected the heptafluorobutyrlsilyl ether of deoxynivalenol by IEC or single-ion MS after GC separation. Schweigbardt et al. (182B)gave separate HPLC schemes for separating the aforementioned toxin and zearalenone from food. A systematic approach to detect ten Fusarium toxins using Florisil and XAD-4 column purification before TLC and GC was given by Kamimura et al. (116B). Ilus et al. (106B) followed kieselgel TLC with high-performance TLC in a method for Fusarium toxins in grains. Suzuki et al. (203B) capitalized on the EC response of butenolide to create a GC method for this toxin. Radioimmunoassays for T-2 toxin were reported by Lee et al. (130B)in milk and (129B)in corn and wheat. Pestka et al. (158B)developed an ELISA test for 'I?-2 toxin that could detect 2.5 pg in 2 h. Chaytor et al. (40B) analyzed for T-2 toxin in corn by conducting GC-MS separation-monitoring at m/e 350 and 436 after trifluorosilylation. A minicolumn screening test for aflatoxin M1 in milk was described by Holaday (94B) that took 10 min. Friesen et al. (68B)had check sample results for M1 in milk that showed better reproducibility for labs using HPLC methods. Lafont et al. (127B) gave their TLC (UV) method for MI in milk powder that included a column cleanup stage first. An interference to HPLC analysis of M1 in milk originating from citrus waste fed to cows was noted by Price et al. (165B). Fremy et al. (66B) presented details of their reversed-phase HPLC-fluorescence method for M1 in milk products and confirmed identity by 'TFA reaction and rechromatography. Pestka et al. (159B)ran both radioimmunoassay and ELISA tests for M1 in milk and found the latter more specific and sensitive. Tripet et al. (211B)separated several aflatoxins in milk products by TLC, using simple one-dimensionalsystems for milk and triple-direction development for complex foods. Van Egmond et al. (2Y6B) confirmed B1 and MI aflatoxins on TLC plates, reacting the spots with TFA and developing in another direction. Biondi et al. (20B) employed a reversed-phase TLC separation in two directions with visual estimation of MIfrom milk. Penicillic acid was converted to a fluorescent derivative &r two-dimensional TLC developmentby Ehnert et al. (56B)who could estimate 5 ng in a spot. Hanna et al. (84B)examined chicken meat and organs for this toxin using HPLC and 254-nm absorption. Cocoa beans were analyzed for patulin and penicillic acid by Chaytor et al. (39B) who employed GC-MS for the TMS volatile derivatives. Seafood toxin methods were reviewed by Ragelis (167B). Shoptaugh et al. (191B)modified the Bates fluorimetric procedure for paralytic shellfish toxintg to assay clams and mussels. Cereals were examined for citrinin by Nakazoto et al. (146B)whose scheme used solvent partition and fluorescence spectrophotometry. Moldy rice was extracted with acetonitrile-water by Schmidt et al. (180B)and measured for sterigmatucystinby HPLC with 246-nm detection. Satratoxins G and H in cereals were separated on Partisil PXS 5/25 with 254 nm absorbance detection in a paper by Stack et al. (196B). Engstrom et al. (59B) discussed losses of Rubratoxin B due to sample handling and gave an HPLC ieilica column method. Heisler et al. (87B)used Cla reversed-phase chromatography to separate Alternaria toxins, monitoring at 324 and 278 nm. Lafont et al. (126B) could separate PR toxin by direct TLC or else convert it to an imine derivative before TLC, measuring both species after further conversion to H fluorescent derivative on the plate. Tenuazonic acid was extracted from tomato paste by Scott et al. (183B) who did paired-ion HPLC or ion exchange separation after solvent partition cleanup. Pyrrolizidine alkaloids in goats milk were converted to retronecine first and then derivatized to the heptafluorobutyrates before EC GC by Dienzer et al. (50B). These compounds were also separated by reversed-phase HPLC and confirmed by MS and GC-MS of TMS derivatives in a study by Dimenna et al. (53B).
The analysis of natural and synthetic hormone levels in foods and feeds using HPLC was reviewed by Jaglan et al. (110B).Purdy et a1. (166B)added tritiated progesterone to sample extracts before gradient HPLC on a Diol column with UV and radioactivity effluent measurement and separated progesterone and Len metabolites of it. An enzyme immunoassay for progesterone was described by Arnstadt et al. (12B)who applied it to milk. Veal was analyzed for stilbene derivatives by radioimmunoassay (RIA) as well as GC-M8 by Brunn et al. (30B) who discussed the relative merits of the methods. Gauch et al. (71B) examined foods for synthetic stilboestrols by separating dansyl derivatives by silica gel 60 TLC followed by an alumina TLC step or else HPLC for confirmation. A RIA procedure for 17-P-oestradiol in rnilk or plasma was detailed by Glencross et al. (79B). Detection of oestrogenic hormone traces in meat with an electrochemical detector scanning HPLC effluent was demonstrated by Frischkorn et al. (69B)who proportioned lithium electrolyte into the mobile phlase. Penicillin traces in milk were detected down to 10 ppb by Miura et al. (142B) with an enzyme immunoassay using fluorescencedetection. Mochalov et al. (143B)discussed GC EC and TLC methods for penicillin in milk. A scheme to identify penicillin, ampicillin cephapirin, and cloxacillin was presented by Herbst (92B) based on an agar-well diffusion bioassay. Nose et al. (148B) reported a method for multisynthetic antimicrobial detection in meat products based on selective ion exchange and Florisil adsorption, desorption, and GC or fluorescence measurement. Hoshino et al. (100B) methylated clopidol with diazomethane after extraction firom chicken and eggs and measured residues with EC GC. Ornori et al. (152B)also performed diazomethane methylation and EC GC, but confirmed clopidol with GC-MS. Turkey was examined for iproriidazole and its metabolite by Garland et al. (70B) with GC-MS on a Silar 1OC column. Methods for sulfonamidesin foods and feeds were reviewed by Horwitz (9823)who called for more collaborative study on the chromatograplhic ones. Horwitz (99B) also discurised performance limitations of sulfonamide residue methods, noting that the Bratton-Marshall is too insensitive for the regulatory limit. HPLC separation with electrochemical detection gave Alawi et al. (5B)detection limits of 10 ppb in milk for sulfonamides. Nukiyama et al. (150B)used UV absorption at 260 nm for HPLC detection after first cleaning up sulfanilamide traces on a silica gel column. Vilim et al. (221B) screened pork for sulfamethazine traces by Bratton-Marshall and HPLC methods, confirming positives with TLC. Thomas et al. (207B)analyzed pork for this drug, doing a fast screen on a TLC plate that was then visualized with fluorescamine. Suhre et al. (202B)added carbon-13 labeled sulfamethazine to pork extracts and ratioed 12Cdrug peaks to those with 13C by GC-MS. Parks (157B)screened for the drug by ion-]pair extracting with tetrabutylammonium hydroxide before TLC. Matusik et al. (138B)found the Manual and Steller method satisfactory for sulfamethazine metabolites after some modification. That method-Manual et al. (135B)-involved extraction, diazomethane methylation, and EC GC measurement. Malonski et al. (134B)compared GC, GC-MS, and colorimetricmethods for pork samples, finding GC-MS more definitive. Honey was analyzed for sulfathiazole residuecg by Argauer et al. (10B)with HPLC at 294 nm following a silica gel column cleanup. Juergens (115B)also reported an HF'LC separation by using ion pairing for sulfathiazole and a H3P04-CH3CN mobile phase for chloramphenicol. Hollstein et al. (96B) determined chloramphenicol in milk by EC GC of its TMS derivative. Antibiotic residue testing in milk was reviewed by Billon (19B). A method for levels of 50 ppb oxfendazole in milk was published b Tsina et al. (213B)who conducted a reversedphase H P L 8 separation. Tetracycline drug resides in honey were detected in H[PLC effluents at 272 or 357 nm in work by Juergens (114B). Ivermectin levels in cattle and sheep were followed over time using HPLC-fluorescence methodology by Tway et al. (215B). Alykov (6B)determined aminoglycoriide antibiotics in milk and biological fluids by extraction and fluorimetry. Vancomycin residuals in cooked lobster meat were traced by Herbst (91B)using bioautography. Traces of xylazine in foods were determined down to 90 ppb by Rogaitad et al. (171B) using packed and capillary GC with N-P (and flame ionization detectors. Furazolidone in fowl and cattle ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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was measured by Heotis et al. (9OB)by multiple development TLC after solvent partition cleanup. Winterlin et al. (233B) reported sensitivity to 0.5 ppb for this drug in turkey with their HPLC procedure. Egg yolk and albumin were analyzed by Taylor et al. (206B) for xylonidine by means of capillary GC-MS and levels were followed during the time after treatment. Wood et al. (235B) reported modifications to a DPP electrochemical method for nicarbazin in chicken that functioned to detect the 0.1 ppm regulatory level. Sakano et al. ( I 76B) used HPLC to monitor residues of diaveridine in chicken eggs and meat and could also measure sulfaquinoxaline with the method. Meat was assayed for traces of oleandomycin by Rutczynska-Skonieczna (174B) who separated the drug by two-dimensional TLC. This author (173B) also used 2-D TLC for ethopabate residues in eggs. Bluethgen et al. (21B) derivatized and determined several fasciolicides in milk by GC. Amprolium traces in chicken and eggs were measured by Petz et al. (161B)with N-specific GC after a preliminary distillation as picoline. Nitrosamines are among the organic species whose electrochemistry was reviewed by Bratin et al. (24B). Hotchkiss (102B) reviewed the advances in separation and specificity for nitrosamine analysis in foods over the past decade. Klein et al. (119B)discussed nitrosamine literature methods for food and beverages. Sen (187B) reviewed TLC methods for nitrosamines. Walters (224B) also presented a short review on N-nitroso compounds in food. A method for N-nitrosodimethylamine (NDMA) in malt beverages was described by Hotchkiss et al. (103B)which introduced a methylene chloride extract into a GC-TEA system without cleanup. A beer method by Andrzejewski et al. (8B)distilled first from caustic and partitioned NDMA into solvent from the distillate before GC-TEA. Aitzenmueller et al. (4B)discussed possible artifacts in beer analysis that might be formed. Mark1 et al. (136B) compared nine techniques for NDMA analysis in beer and brewing materials, finding that direct CHzClz extraction bettered distillation. Sen et al. (188B) treated beer with sulfamic acid and HC1 before distillation, CHzClzextraction, and GC TEA analysis. Owens et al. (154B) constructed a liquid nitrogen controller to regulate cold trap temperatures in a TEA analyzer. Verhagen et al. (220B)reacted NDMA to a secondary amine which when derivatized with 443-7nitrobenzofuran was measured by fluorescence HPLC. Cross (47B) reviewed methods for volatile nitrosamines in bacon. Owens e t al. (153B) gave improvements to the mineral oil distillation method for volatile nitrosamines in bacon fat. Sen et al. (189B) gave a fast liquid-liquid extraction for volatile nitrosamines in bacon fat, which were then injected into a GC-TEA. Massey et al. (137B) demonstrated that the low flows of microbore HPLC could make an LC technique amenable to a TEA analyzer. Nonvolatile nitrosamines were detected by Samuelsson et al. (177B)using DC, normal pulse, and differential pulse voltammetry. Hotchkiss et al. (104B) used a combined GC-TEA and GC-MS system to confirm the identity of volatile nitrosamines separated on packed and capillary columns. Havery et al. (85B)gave a fast method for volatile nitrosamines in milk consisting of CHzClzeluates from a celite column directly injected into GC-TEA. Gilbert et al. (75B)presented a review on advances in trace diet constituent analysis, covering nitrosamines, dioxins, and mycotoxins, emphasizing MS methods. Dougherty (55B) reviewed trace analyses for contaminants that are facilitated with negative-ion chemical ionization MS. Hydrocarbons due to pollution could be differentiated by Berthou et al. (16B) from those of biological origin by diastereomer distribution as determined by glass capillary GC with MS detection. Adachi (1B) employed GC-EI-MS to fingerprint crude oil contamination of oysters by poly(methylnaphtha1ene) and poly(methy1phenanthrene)detection. Kwan et al. (125B)were able to establish trends relating to mussel proximity to pollution sources by applying pattern recognition routines to hydrocarbon composition. Organic sulfur species in clams and eels were identified by GC-sulfur photometric detection and GC-MS by Ogata et al. (151B)who developed information on marker compounds for crude oil pollution. Adachi (2B)detected poly(methylbipheny1s) using GC-MS to examine extracts from rice contaminated with petroleum. Min et al. (141B)found they could measure biphenyl and phenyl ether in oil by a purge and trap technique a t 160’. A method for polynuclear aromatic hydrocarbons (PNA’s) in beer was del 6 8 R * ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
veloped by Joe et al. (112B),cleaning up an isooctane extract on alumina before HPLC with UV absorption and fluorescence detectors in series. Gertz (74B) used a nonionic detergent in petroleum ether to extract 3-4-benzopyrene from food, and then complexed it and other PNA’s with caffeine-formic acid before a column cleanup, HPLC, and TLC. Kolarovic et al. (121B)used caffeine complex formation to extract PNA’s from vegetable oils and ultimately separated them by capillary GC after TLC group segregation. The Gertz procedure for PNA compounds in smoked meat and fish was extended to fatty foods by Van Heddeghem et al. (217B) using caffeine complexation and cleanup before HPLC with fluorescence detection. Sagredos et al. ( I 75B) gave details for a TLC separation that included a preliminary caffeine complexation of PNA’s. Tonogai et al. (210B)published a rapid procedure for benzo[a]pyrene that used a fluorimetric base line construction after alumina cleanup. Vassilaros et al. (219B)extracted PNA’s from fish and fractionated them on alumina to separate aliphatics and S- and N-containing moieties and then performed further GPC or capillary GC-MS separations for identity. The history and analysis of polychlorinated biphenyls (PCB’s)were reviewed by Cairns et al. (33B). These authors (34B) compared GC-MS and EC-GC methods for PCB measurement and discussed the superior freedom from interfering compounds with chemical ionization MS detection. A splitless GC capillary separation with electron capture detection was the basis of a method for PCB’s in milk fat by Tuinstra et al. (214B). Kuehl et al. (124B)examined tissues for chlorophenols and PCB’s using chemical ionization negative-ion MS after GPC or steam distillation cleanup. Morton et al. (145B) analyzed for pentachlorophenol (PCP), pentachloroanisole, and the 2,3,4,5 and 2,3,5,6 isomers of tetrachlorophenol ethylating the phenols before EC GC in a mewere thod for fat samples. PCP and 2,3,4,6-tetrachlorophenol extracted from gelatin by Stijve (198B)who chromatographed them on a DEGS-H3P04 column with EC detection. Brugel (27B)converted PCP to the acetate before EC GC in a method for gelatin. Borsetti (22B)analyzed milk and cattle blood for PCP residues by extraction and EC GC on an SP 1000-H,P04 packed column. Mason jar lids and preserved food were analyzed for PCP by Heikes et al. (86B)who methylated to pentachloroanisole before EC GC. PCP residues in mushrooms were determined by Schoenhaber et al. (181B) using steam distillation, extraction into CHzClz,and either GC after acetylation or direct HPLC. Residues of 2,3,7,8-tetrachlorodibenzodioxin in goats milk were detected down to the low part-per-trillion level using GC-MS and monitoring the 321.9 m / e ion in work by Raisanen et al. (169B). Brumley et al. (29B) monitored 12 ions and calculated ratios in a low-resolution GC-MS method for the 2,3,7,8 compound in fish. Aitzenmueller et al. (3B)analyzed milk for 2-hydroxybiphenyl using an Extrelut column extraction and normal-phase silica HPLC after elution and concentration. The presence of 4nitroso- and 4-nitrophenols in smoked fish was shown by Borys (23B)who separated them from alkylphenols and phenol by HPLC after XAD-4 concentration. Ivie et al. (109B) investigated carrots for psoralen presence using HPLC techniques but found none. Wells et al. (228B) analyzed fish for contamination with “Eulan WA New” by methylating extracts with CH31and tetrabutylammonium hydroxide before EC GC. A literature review on the migration of packaging material components into foods led Niebergd et al. (147B)to speculate that model systems should predict potential migration from partition properties. Gilbert et al. (76B)reviewed headspace GC methods used to measure residual monomers in plastic packaging. Ettre (61B)reviewed the purge and trap method as a way of extending detection limits for residual printing solvents in packaging film, among other applications. Hollifield et al. (95B) gave a multiresidue scheme wherein headspace vapors from packaging were compared to computer-stored retention times. Colli (44B) discussed common solvents and GC methods for packaging ink volatiles. A method for volatiles originating from food packages using empirical headspace calibration was presented by Eiceman et al. (57B). Habegger et al. (80B) gave a heated headspace method for residue solvents in packaging films that used cyclohexane as an internal standard. Kolb et al. (123B) discussed a GC “multiple headspace extraction” for printed films in which successive vial gas flushes are summed to approximate total partition. Vinyl chloride oligomers were
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ether-extracted from resins and separated by SEC on BioBeads or Sephadex before GC analysis with packed and capillary columns5 monitored by FID, Hall, and MS detectors, in a study by Gilbert et al. (77B)who also used a silica LC separation to segregate non-C1- from C1-containing extractables. Vreden et al. (223B) attempted to quantify migratedstyrene monomer by direct GC of headspace over strawberries but found volatile aroma interferences. Styrene monomer was extracted from polystyrene-contacted foods with hexane and reacted with bromine water to form the bromo compound by Novitskii et al. (149B)who then performed EC GC. Gilbert et al. (78B)monitored m / e 104 for styrene liberated from food heads ace and separated by packed-column GC-MS. Palla (155Bf also employed GC-MS for styrene traces, adding deuteriostyrene to wine samples, brominating extracted monomer, and ratioing the 2H to ‘H fragments shown. Sponholz et al. (194B)developed a HPLC method for styrene in wines, measuring it at 254 nm in a reversed-phase effluent. Gawell et al. (72B)added a-methylstyrene before distilling foods from MeOH/H20 arid then performed reverse-phase HPLC. Another version of a HPLC method by Varner et al. (218B) analyzed directly for the monomer by dissolving polystyrene in THF, precipitating polymer with MeOH, and then injectin supernatent. Additional experiments by Watabe et al. (225Bj demonstrated the ability to selectively retard polar components vs. styrene with CC on a liquid crystal stationary phase in an electric field. Baumann et al. (14B)investigated aromatic amine migration into food-simulating solutions with electrochemically detected HPLC separations. Traces of 2,4- and 2,6-toluenedimine from food boilable pouches were measured by Snyder et al. (193B) by concentration before HPLC with 254-nm detection. Ardrey et al. (9B)listed extensive data on retention indices of GC-separable compounds among which were plasticizers, antioxidants, contaminants, etc. A cleanup for bis(2-ethylhexyl) phthalate traces in fish oil that used Bio-Bead and alumina columns before EC GC was given by Burns et al. (31B). Haesen et al. (81B)studied the migration of phenolic antioxidants from plastic to oil with a TLC technique and color development. Haesen et al. (82B) analyzed dairy produds for antioxidant migration with TLC also. The sizing compound distearylcarbamoyl chloride was measured in olyethylene-coated papers by HPLC at 254 nm in a methoif by Helmer et al. (88B). Zimmerlie et al. (237B) reviewed tetrachloroethylene in foods and proposed a distillation-GC method. A heated headspace method for halocarbons in foods was described by Entz et a1. (6013) who analyzed the vapors with EC GC and found variations in the vapor phase partition depending on the food matrix. Saxby et al. (179B) also published a vialheads ace GC technique for solvent residues due to be regulateifby the EEC, and found that calibration slopes depended on matrix and CHzClzcould not be separated from coffee aroma. DiPasquale et al. (54B) experimented with oxygen doping of nitrogen carrier gas to enhance the electron capture sensitivity of CHzClzresidues in oils and liquid foods. Kolb et a1. (122B) determined residual perchloroethylene in eggs using an OV-101 capillary column and EC detection on a headspace sample. Ethylene oxide residues in food were swept out by nitrogen and measured by EC GC after conversion to 2-bromoethanol on a Florid-HBr column gas scrubber in spice analyses conducted by Mori et al. (144B). King et al. (118B)analyzed headspace above blended grapefruit by EC GC for methyl bromide residues. An electron capture GC method by Rains (168B)separated ethylene dibromide extracted from flour and biscuits with hexane. Reaction products of ethylene oxide and theobromine were identified by mass and UV spectroscopy studies after TLC separations of cocoa extracts in a report by Pfeilsticker et al. (163B). Scudamore (186B)could determine 0.2 ppb residual 2-aminobutane in potatoes with HPLC separation and fluorimetric detection of the dansyl derivative. Arikawa et al. ( I I B ) examined vegetables for traces of acrylamide, extracting, brominating, and finally conducting an EC GC separation on a cleaned-up fraction. Cox et al. (45B)reported a method valid in the 10-60 ppb range for chlorobutanoltraces in milk by using a combined distillation-extraction and EC GC. Beck et al. (15B) derivatized 1,2,3,4-tetrahydro-1methyl-&.carbolinewith pentafluoropropionicanhydride after extraction and measured it by monitoring single ions from capillary EI-GC-MS. Phenol at low parts-per-million levels
in honey was quantified by Sporns (195B)by HPLC with UV absorbance monitorin on a steam distillate. Kid0 (117B) measured formaldehyfie in fish paste by reacting steam distillates with 2,4-dinitrophenylhydrazinebefore FID-GC. Cline et al. (42B)formed a pentafluorobenzyl ester of the benomyl metabolite carbendazim to inject it into an EC GC for estimation in walnuts. Grapes and wines were analyzed for imidazolidine-Qthione traces by Caccialanza et al. (32B) who separated it on a reversed-phase HPLC column monitored at 240 nm. The toxaphene metabolite camphechlor was determined in milk fat b,y Cairns et al. (35B),using methane CIMS of packed-column GC effluent. Swallow et al. (204E) compared their GC detection procedure for tutin and hyenanchin in honey to a mouse assay. A method for 4(5)-methylimidasole in food formulated with caramel color was presented by Yoshikawa et al. (23%) which diazotized the compound before TLC separation as a colored species. Thomsen et al. (208B) determined the aforementioned caramel impurity by HPLC ion-pair separation and detection at 215 nm. Roy et al. (172B) automated a uric acid method that measured a color developed with phosphotungstic acid before and after immobilized uricase contact. Spice contamination with uric acid was correlated to insect infestation by Brown et al. (26B) who monitored oxygen released from a uricase reaction with a specific electrode. Wolfschoon-Pombo et al. (234B)used a test kit that coupled uricase action on uric acid in milk to a catalase reaction and then dehydrogenase,finally measuring a NADH absorbance change to estimate the uric acid content. Hoover et al. (97B)discussed using jack bean meal as an economical source of urease. Thrasher et al. (209B) tested for alkaline phosphatase in suspect particles to confirm mammalian faeces. Scott et al. (185B)solvent extracted ergot alkaloids from flour with a partition cleanup before reversed-phase HPLC with fluorescence detection. Dent (51B) reported collaborative results of the operations necessary to separate thrips and similar insects from frozen blackberries and raspberries. L h (132B) had data on a collaborative study on light filth in tea. Freeman (65B) modified the procedure for extracting light, filth from sage. This author (64B)also described a method for light filth in corn. A method for indole in shrimp was developed by Chambers et al. (36B)in which1 the compound is extracted with methanol and separated on a C18 HPLC column with fluorescence detection. These authors (37E) also gave a procedure that extracted into ethyl acetate and cleaned up on a polyamide column before HPLC with 217-nm absorbance detectiion. Cheuk et al. (41B)determined indole colorimetrically without steam distillation. Takahashi et al. (205B)measured dimethyl sulfide in incubated headspace over rice to correlate its precursor with age andl storage. Meltzer et al. (140B)develolped a method to detect cyclic compounds formed from polyunsaturated 1Scarboln fatty acids when soya bean oils were extensively heated. Henion et al. (89B)analyzed for histamine in tuna fish by capillary separation of ita TMS derivative with positive ion CI MS detection.
CARBOHYDRATES Increased use of IHPLC for the determination of individlual sugars is the outstanding feature of the literature reviewed in this period. It ha3 unfortunatelybeen necessary to eliminate some articles which report similar techniques because of lack of space. Automatic methods for reducing carbohydrateshave been described by Boehringer et al. (18C) using the reaction with 4-hydroxybenzohydrazide and by Robin et al. (109C) using tetrazolium lblue after gel chromatography and with parallel detection with orcinol. Polyamide powder has blsen suggested by Lehmann et al. (70C) as a means of removing pigments in the analysis of chocolate for sugar. The use of glycerine in sodium hydroxide as a replacement for Fehling’s B solution has been proposed by Ma (72C).A reagent containing phenolphthaleinhas been used by Shahine et al. (11112) for the indirect spectrophotometricdetermination of reducing sugars. A glucose sensing electrode using glucose oxidase, in conjunction with a glassy carbon electrode, has been descrilbed by Matsumoto et al. (77C)to measure glucose in orange juice. Brobst et al. (21C) have reviewed three chromatographic methods for the analysis of sugar mixtures, HPLC, GC, and TLC and suggest that the method chosen depends on the nature of the sample. A minicolumn of aluminum oxide has been used by Gorin et al. (46C) to clean up onion extract ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL
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before HPLC chromatography. Iverson et al. (58C) have compared the separation and ease of preparation for the analysis of five sugars by HPLC and GLC and found the GLC method not applicable to all foods. After extraction with 80% ethanol Quemener et al. (97C) have separated four oligomers from leguminous seeds by HPLC. Two detectors of monosaccharides separated by HPLC have been compared by Binder (15C) who reports finding much greater sensitivity at 188 nm than is obtained by refractive index detection. Fluorimetricdetection of sugar borate complexes after reaction with 2-cyanoacetamide has been used by Honda et al. ( 5 5 0 in the automated HPLC analysis of reducing sugars. The mass detector has been found by Macrae et al. (73C) to provide greater sensitivity and stability than the refractive index detector in the HPLC of carbohydrates. An amperometric detection technique has been used by Hughes et al. (56C) for carbohydrate detection after HPLC separation. Semiquantitative and qualitative determinations of sugars have been described by Qureshi et al. (99C) on capillary tubes partly filled with diphenylamine hydrochloride. Near-infrared reflectance spectroscopy has been examined for its usefulness in determining individual sugars in dry mixtures by Giangiacomo et al. (44C), and preliminaryresults appear promising. An enzyme scheme which determines D-glucose, D-fructose, and D-mannose has been described by Sturgeon (113C). Various separations of sugars on chemically modified silica gel, with bonded amino groups, have been described by Orth et al. (92C). Fluorodensitometric measurement has been applied by Iwakawa et al. (59C) to sugars separated on TLC plates and sprayed with ethylenediamine sulfate. Silica columns impregnatedwith HPLC Aminc Modifier 1have been used by Aitzetmueller (4C) for the analysis of carbohydrate mixtures such as fruit juices, jams, and syrups. Akhavan et al. (5C) have compared the effectiveness of ion-exchan e cleanup with that of lead precipitation for acids before 8 C determination of sugars and find ion-exchange preferable. Sugars in sugar refinery products have been determined by Charles (25C) by HPLC using refractometric and conductometric determination. Cellobiose dehydrogenase has been used by Canevascini et al. (24C) for the direct determination of lactose in milk and milk products. An enzyme procedure using p-D-galactosidase to hydrolyze lactulose, a series of enzymes to remove glucose, and then to determine the fructose as a measure of lactulose has been proposed by Geier et al. (42C). Parrish (94C) has studied spectrophotometric procedures and HPLC for the analysis of lactulose and other sugars in sugar mixtures and found the HPLC method faster and as accurate. Sugars and polyhydric alcohols have been separated by Angyal et al. (8C) usin HPLC on cation exchange resins in the calcium form. TL after extraction and purification has been applied by Maier et al. (74C) to the determination of esters of sugars and fruit acids in foods. A collaborative study has been conducted by Zygmunt (125C) on the HPLC determination of mono- and disaccharides in cereals and the method has been adopted as official first action. An HPLC technique has been developed by Brandao et al. (19C) to separate and quantitate mono- and disaccharides and sorbitol, using HPLC columns in tandem. Mono- and disaccharides have been anal zed by Adam ( I C ) using as chromatography of sodium orohydride derivatives, eit er trimethylsilated or acetylated. Fluorescaminehas been found by Chen et al. (27C) to be useful for the quantitative analysis of amino sugars and of chitin. Reviews of analytical procedures for polysaccharides have been published by Aspinall (9C) and Heyraud et al. (52C). High-resolution separation of oligosaccharides has been reported by Scobell et al. (109C) using silver-form cation exchange resins. Two HPLC columns in series have been used by Fonknechten et al. (38C) to separate oligosaccharides. Three cation exchange columns, Ca form, connected in series have been used by Schmidt et al. (106C) for the separation of malto, xylo, and cello oligosaccharides. Carbohydrate oligomers have been separated by Cheetham et al. (26C) using a radial compression module. Waniska et al. (122C) have compared ultrafiltration, gel permeation, and adsorption chromatography methods for separating oligosaccharides, the latter was found to be the most efficient and effective. A “reaction column” which converts nonreducing sugars to reducing sugars, placed after a separation column and followed by a reducing sugar reagent, has been proposed by Vratny et
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al. (121C) for the determination of nonreducing oligosaccharides. HPTLC using multiple developments has been applied by Nurok et al. (88C) to the separation of malto oligosaccharides. Cryoscopy has been proposed by Fitton (36C) as a rapid means of determining dextrose equivalent. Methods for the determination of pentosans have been described by Douglas (32C) using spectrophotometry after controlled acid treatment and by Folkes (37C) by gas chromatography of the furfural produced after acid treatment. Dextran in cane juice has been determined by Li Sui Fong et al. (71C) by haze measurement before and after dextranase treatment. Radley (1OOC) has edited a book on starch and analysis of starch products. A method for starch analysis in cereal products has been reported by Batey (12C) which uses thermostable a-amylases. A method for amylose in milled rice has been submitted to international cooperative testing by Juliano et al. (63C) and the effects of defatting were determined. Amperometric titration with iodate-iodide solution of starch in a dimethyl sulfoxide-water system has been described by Voss et al. (120C)for the determination of amylose content. A calibration has been devised by Osborne et al. (93C) which measures the degree of starch damage in flour by near-infrared reflectance analysis, A sensitive method using @-amylase-pullulanasehas been suggested by Kainuma et al. (64C) for the determination of the degree of gelatinization and retrogradation of starch or starch products, and Kugimaya (68C) has proposed measuring the susceptibility of the starch to @-amylaseas a means of characterizingits gelatinized state. GLC has been used by Mitchell et al. (81C) as a means of determinin the adipate content of acetylated distarch adipate. Hydroxyallyl groups in etherified starch have been determined by GLC analysis of the reaction products with hydriodic acid, by Kawabata et al. (65C), and hydroxypropyl groups have been determined by Tsai et al. (117C) by a colorimetric procedure. Galactomanman in guar seeds has been analyzed by McCleary (78C)using the enzyme galactose dehydrogenase. @-Glucanin barley has been determined by Martin et al. (76C) after treatment of extracts with cellulase and enzymic determination of the released glucose. An automated method for glycogen has been developed by Haagsma et al. (47C) using amyloglucosidase and enzymic glucose determination. A review of methods for polysaccharide thickening agents in foods has been published by Scherz et al. (105C). General methods for these polysaccharideagents have been described by Pechanek et al. (95C) using electrophoresis separation, by Friese (40C) using TLC, by Mergenthaler et al. (79C) using separation on DEAE cellulose columns and TLC or GLC analysis after hydrolysis, and by Hunziker et al. (57C) using gel permeation chromatography. This technique has also been used by Barth et al. (1IC)for the separation of water-soluble cellulosics. Another procedure for analysis of natural thickeners and gums has been described by Preuss (96C) using methanolysis and capillary gas chromatography. Gas chromatography has been proposed for the analysis of thickeners in milk products by Glueck et al. (45C) after separation from the product and hydrolysis. Alginate in beer has been determined by Schur et al. (107C) using a colorimetric determination for mannuronic acid separated by TLC after hydrolysis of the gum and by Fey et al. (35C) by a similar procedure after separation of the alginate by the use of Sephadex G-50. Carrageenan in dairy products has been determined by Murray et al. (86C) by fluorimetric assay with acridine orange. Galacturonic acid has been determined by Birnbaum et al. (16C) using an enzyme method, and by GLC after enzyme hydrolysis and potassium borohydride treatment by Ford (39C). Oli ogalacturonic acids have been separated by Thibault (116C)%ychromatographyon polyacrylamide gel. The use of m-hydroxydiphenylas chromogen forming reagent for anhydrogalacturonic acid has been recommended by Robertson (102C) for the determination of pectic substances in fruits. Dissolved pectin in fruit juice has been determined by Meurens (80C) by iodometry of the cupric copper precipitated with pectate. A method for the molecular weight distribution of pectins has been developed by Barth (1OC) using gel permeation chromatography. A near-infra red reflectance technique has been found by Wingfield (124C) to be useful for the detection of cellulose in flour. James et al. (61C) have edited a treatise on the analysis of dietary fiber in food covering various procedures and problems. Four dietary fiber procedures have been compared by Heck-
FOODS
man et al, (50C) who found the Furda method to be practical, to be informative and to have acceptable precision. The details of this method which determines soluble and insoluble fiber have been published by Furda (41C). Methods for analysis and chemical characterization of dietary fiber have been published by Theander et al. (115C), Selvendran et al. (IIOC), and Schweizer et al. (108C). All use hydrolysis after separation to determine constituents of the fiber components. A SUCcessful collaborative study of the Goering and Van Soests neutral detergent fiber method has been reported (6C) on six products. Studies of neutral-detergent fiber methods have been carried out by ColWinge et al. (28C) comparing different enzymes, temperatures, and digestion sequences, by Roth et al. (104C)who suggest the use of p-glucanase to help filtration of barley kernels, by Dovell et al. (330 who propose a method for fiber in oranges and other foods, and by Anderson et al. (7C) who have exhaustively analyzed the dietary fiber of corn bran. Characterization studies of dietary fiber have been reported by Bither et al. ( I 7C) who reported the neutral and acidic composition of the alcohol insoluble residue from foods, by Brillouet et al. (20C) who reported on the fractionation of wheat bran noneitarch polysaccharides, and by Belo et al. (13C) on the analysis of pectic substances in detergent-extracted dietary fibers. A method for characterizing lignin has been described by Hedges et al. (51C) using gas capillary chromatography of cupric oxide oxidation products. Cell-wall polysaccharide and lignin levels have been determined by Riquet et al. (101C) by different methods who found that a sharp separation of these polysaccharides was not obtained by the Van Soest methods. Modifications of the Van Soest methods have been suggested by Marlett et al. (75C) for the improved determination of lignocellulose and hemicellulose. A method for the determination of starch in dietary fiber sources hm been proposed by Dintzis et al. (31C) using enzyme treatments Nonstarch polysaccharides have been determined in plant foods by Englyst et al. (34C) by GLC of constituent sugars as alditol acetates. Craddick et al. (30C) have suggested that glass filter paper be substituted for the fritted glass crucible in asbestos-free fiber determinations. Glycerol in wine has been determined by Ubigli (119C) after oxidation to formaldehyde which is then determined as the 3,5-diacetyl-1,4-dihydrolutidine. Components of maltitol-Dsorbitol Eiyrups have been separated by Molnar-Per1 et al. (82C) by GLC after trimethylsilylation. Pinitol and other cyclitols have been analyzed by Ghias-Ud-Din et al. (43C) by HPLC with refractive-index detection. D-Sorbitol has been Separated from foods by dialysis and determined by GLC by Tsuda et al. (118C). Sugar alcohols in gum have been determined by Oesterhelt et al. (9OC) by GLC of the TMS or acetyl derivatives after water extraction. A modified acetylation procedure has been applied by Mount et al. (84C) to the estimation of sugar alcohols by GLC. Monoterpene glycosides and norisoprenoidprecursors from grape juices and wines have been separated by Williams et al. (123C) by reversed-phase column chromatography on CIS bonded phase columns. Phytoestrogens from soya beans have been determined by HPLC by Murphy (85C) using gradient elution. Recent advances in the analysis of glucosinolates have been reviewed by Olsen et al. (91C). Glucosinolates have been analyzed by Heaney et al. (48C) using gas chromatography and the same authors (49C) report on the importance of the derivatization conditions for the determination of indole glucosinolates. Sinalbin and sinigrin have been determined by isotachophoresis and conductometric detection by Klein (67C). Neohesperidin dihydrochalcone has been separated from intermediates and from alcoholic beverages by Tateo et al. (114C) using liquid chromatography with gradient elution. Stevia components in natural sweetener products have been analyzed by TlLC and GC by Nakajima et al. (87C), by Iwamura et al. (CiOC) by thin-layer densitometry, by Hirokado et al. (53C) by silica gel TLC, and by Ahmed et al. (2C, 3C) by HPLC! from leaf samples. Isolation and detection of saponins in food have been included in a review by Oakenfull (89C). Potato glycoalkaloids have been determined by HPLC by Bushway et al. (22C), by radial compression HPLC by Morris et al. (83C), by a modified titration method by Bushway et al. (23C), by a rapid colorimetric method by Bergers (14C), by TLC by Coxon et al. (29C), and by fluorodensitometric TLC by Jellema et al. (62C). Vicine and convicine have lbeen determined by HPLC by Quemener et
al. (98C) and Lattanzio et al. (69C), by colorimetry by Kim et al. (66C),and by color development after TLC by Hoehn et al. (54C). Zeatin and zeatin riboside have been determined by HPLC by Stahly et al. (112C) after extraction from pears, peaches, and apples.
COLOR Artificial and natural colors, plant pigments, and related compounds are included in this section of the Review. A review of chromatographic and spectrophotometric methods for the determination of natural and synthetic coloring materials has been published by King (460). The use of HPLC to separate food dyes has been described by Maslowska et al. (510)using P1C reagent A, by Boley et al. (110)with methanol-H20 plus cetrimide as mobile phase, by Lawrence et al. (490) using ion-plair chromatography with tetrabutylammonium phosphate, and by Puttemans et al. (610) using the same counterion. Ion-pair extraction and ion-pair (adsorption TLC have been used by Van Peteghem et al. (710) to analyze 17 food dyes. The use of photoacoustic spectroscopy after thin-layer chromatography has been proposed by Ashworth et al. (40) for the determination of several food dyes. A scheme for extraction and separation of water-soluble artificial acidic dyes hias been prepared by Corradi et al. (180) using TLC. Ion-pair thin-layer chromatography has been applied by Gonnet et al. (360)to the analysis of water-soluble food dyes. Food colors have been determined by Fogg et al. (300) by dc voltaminetry with good precision. Polarographic behavior of some azo dyes has been studied by Hart et al. (370) and optimum conditions for determination by differential pulse polarography have been established. An extraction procedure for water-soluble colors from foods using polyamide columnti has been proposed by Crosby (240). Ion-pair extraction has been suggested by Puttemans et al. (630) to transfer dyes from water extracts to chloroform1 as a cleanup technique. The same authors (620) have evaluated TLC, paper chromatography, and HPLC for identification of dyes extracted as ion pairs and found the extraction to be essentially quantitative (600). Dyes after water extraction have been adsorbed on polyamide and then eluted with methanol and identified by photometry on TLC by Ogiwara et al. (570). A system for extracting and determining dyes in chewing gum has been described by Andrzejewska (1D) with identification by TLC. Ion pairing HPLC has been suggested by Hurst et al. (410) for the analysis of amaranth in licorice products. Indigo carmine has been determined by Boley et al. (120) in boiled sweets by HPLC after extraction amd cleanup on a Sep-I’AK CI8 cartridge. Tartrazine has been determined in foods by Hurst et al. (420) by HPLC, aind Kobori et al. (470) have studied the polarographic behavior of this dye for quantitative estimation in foods. Differential pulse polarography has been found by Fogg et al. (310)to be of use in studying the degradation of Red 10 B during processing. HPLC haai been applied by Bdiley (50) to the (determination of intermediates in FD&C Blue No. 2, by Cox et al. (230) and by Calvey et al. (160) to similar analyses of FD&C Yellow No. 5, and the procedure for intermediates and byproducts in FD&C Red No. 40 has been submitted to collaborative study by Cox et al. (220). Natural pigments have been separated by TLC on polyamide by Kanada et al. (450). An identification method for color E 160b (oriana, annatto) has been described by Corradi et al. (200) using TLC to se arate its components. Beet pigments have been analyzed y! Bilyk (100) by preparative TLC followed by a multiple development TLC technique. Beetroot red, E 162, has been analyzed by TLC on silica gel by Corradi et al. (19.D). A fractionation technique for analysis of betalaines has been described by Bilyk (90) after extractiion with ethanol, followed by spectrophotometry and TIL!. Quantitative determination of individual betacyanin pigments has been achieved by Schwartz et al. (660) using HPLC, and Schwartz et al. (670) have compared spectrophotometric amd HPLC methods for quantitation and prefer HPLC. Extractable colorant in ground pepper has been determined by Drdak et al. (280)by methyl ether extraction and colorimetry. Caramel types have been fractionated by gel chromatography by Hellwig et al. (380) into color components, typical elution diagrams facilitate classification. Cochineal has been detected in meat products by Andrzejewska (20) by TLC after purification on polyamide. Curcumin in turmeric has been deANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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termined by Asakawa et al. ( 3 0 )by HPLC after solvent extraction. Mustard has been analyzed for turmeric by Unterhalt (700) by the formation of rubrocurcumin after extraction. Saffron coloring principles have been identified by Corradi et al. (210) by TLC. A review of the advantages of HPLC for separating plant pigments has been published by Schwartz et al. (650). Anthocyanins in grapes have been examined by Piergiovanni et al. (580)using HPLC. The effect of mineral acids used during extraction on the chromatographicprofiie of anthocyanins has been described by Moore et al. (530). Postcolumn reactors after HPLC separation have been found by Galensa (350)to provide quantitative data for flavonoids when applied to tomato skins. Flavonoids in barley and hops have been determined by McMurrough (520) using HPLC, in beer by Delcour et al. (250)using gradient elution HPLC after column cleanup, and in carrots by Yates et al. (730) using column cleanup and GLC. Procyanidins in wines and ciders have been determined by Lea (500) using HPLC. Schemes for the separation of the flavonol glycosides of fruits have been presented by Henning et al. (390) by HPLC with identification by TLC and spectroscopy. The flavanols L-epicatechin and Dcatechin have been isolated from grapes by Baranowski et al. ( 6 0 ) using column chromatography. Hesperidin in orange juice has been determined by Galensa et al. (340)by HPLC after extraction and polyamide cleanup. The flavonoids rutin, hesperidin, and naringin have been determined in citrus fruits by Drawert et al. (270)by GLC and by column and thin-layer separation (260). Hesperidin in orange drinks has been determined by Sontag et al. (690) by HPLC and amperometric detection. Bianchini et al. ( 8 0 )have separated 17 polymethoxylated flavones on an HPLC column with the use of four mobile phases. The hydroxyflavoneglycosides of some spices have been isolated by Hoffmann et al. (400) by paper chromatographyand TLC and identified by UV spectra and by color reactions. Separation and identification of catechins and proanthocyanidins in spices have been described by Schulz et al. (640) by column cleanup followed by TLC. Tea catechins have been separated by gas chromatography by Zaprometov (740). An automatic system for the chromatography of tea catechins has been developed by Nakagawa (550). Gas chromatography of trimethylsilylated derivatives has been used by Nagata (540)to determine flavanols in tea leaves. Theaflavins in tea have been assayed by HPLC by Wellum et al. (720) and by colorimetry with Flavognost by Cloughley (170). A procedure for the analysis of unconjugated pterins in foods has been described by Kohashi et al. (480) using HPLC with fluorescence detection. Methods for tannins in sorghums have been evaluated by Earp et al. (290),and the vanillin-HC1 method is recommended. Synthetic &carotene added to food has been determined by Kamikura (440)using column chromatography on alumina. Carotenes in tomatoes have been determined by Cabibel et al. (150)using HPLC on a magnesium oxide column. HPLC has been used by Bushway et al. (140)to determine a- and @-carotenesin fruits and vegetables. Similarly Baranyai et al. ( 7 0 )have used HPLC to determine carotenoids in paprika products. Reversed-phase HPLC has been described by Braumann et al. (130)as a means of analyzing chloroplast pigments from plants. Chlorophylls and their derivatives in spinach have been determined by Schwartz et al. (680) by HPLC with gradient elution. Methods for evaluating the color of meat samples have been discussed by Pipek et al. (590). Transmission spectrometry has been used by Fransham (320)to evaluate haem pigments in muscle slices. Gel permeation chromatography has been applied by Fraser et al. (330)to the separation and subsequent characterization of the colored components of processed palm oil. Johnston et al. (430)have found good correlation between Hunter color values on semolina and lutein and p-carotene values. As an initial step in the study of oxidative browning in white wine, Nickenig et al. (560) have separated and identified phenolic compounds in the wine.
ENZYMES The presence of enzymes in foods may be used as both a quality index and an index of proper preservation techniques. Interest in analytical methods for these compounds therefore continues to be high. A collaborative study of the determi172 R
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nation of alkaline phosphatase in casein has been reported by Murthy et al. (26E)using a rapid colorimetric test, and the method has been adopted as official first action. The same authors (27E) have studied the use of alkaline phosphatase activity in skim milk impregnated paper disks as a positive control standard. Improved sensitivity for alkaline phosphatase in milk and cream has been obtained by Linden et al. (18E)by the use of additives to induce transparency (and stop the reaction) and thus facilitate the colorimetricreading of the end point. A colorimetric method for the determination of a-amylase activity in cereal products has been published by the British Standard Institution (5E). Collaborative studies have been made by Mathewson et al. (22E) on a-amylase analysis by three methods and (23E) on a simplified rapid colorimetric method for a-amylase; all procedures were applied to sprouted wheat. Isoelectric focusing has been used by MacGregor et al. (20E) to separate and then determine, by using the amylopectin @-limitdextrin plate technique, aamylase enzymes in germinated barley. An explanation of the high falling numbers obtained when a-amylase is determined at bath temperatures lower than 100 OC has been offered by Varriano-Marston et al. (33E), and the effect of altitude on the falling-number value has been discussed by Lorentz et al. (19E). The qualitative official test for egg pasteurization has been compared unfavorably with the Roche Amylochrome test for a-amylase activity by Cattaneo et al. (7E);the latter gives quantitative results. A nephelometric technique for predicting diastatic power in barley has been suggested by Swanston (31E) which measures @-amylase concentration. Luciferase has been used by Ching (BE) in a rapid and sensitive assay procedure for ADP glucose pyrophosphorylase in wheat seeds. Ascorbate oxidase in wheat flour has been isolated and characterized by Pfeilsticker et al. (29E)using thin-layer isoelectric focusing. A polarographic method has been used by Takahashi et al. (32E)to determine ascorbic acid oxidase inhibitor in fruits and vegetables. Rennet enzymes have been fractionated and identified by Reimerdes et al. (30E) using conventional techniques (ion-exchan e chromatography and electrophoresis). Martin et al. &E) have evaluated bovine rennets by using a synthetic hexapeptide; the effect of pH was studied. Chromatography on DEAE cellulose has been used by Collin et al. (12E) to determine chymosin and bovine pepsin A in bovine rennets and pepsins, and McMahon et al. (24E) have evaluated the formagraph, an instrument for measuring milk clotting, for comparing rennet solutions and found it satisfactory. A sulfur dioxide probe has been used by Alexander et al. ( I E )as a sensor in an automated continuous-flowsystem for the determination of glucose oxidase by reacting the hydrogen peroxide from the enzyme reaction with hydrogen sulfite. Lysozyme has been determined in egg white by Galyean et al. (14E)by ion exchange chromatography and UV detection. Measurement of nitrite production has been used by Junker et al. (16E) to determine nitrate reductase in starter cultures. Pectic enzymes in commercial enzyme preparation have been separated by HPLC on a Spheron 1000 column and its ion-exchange derivatives by Mikes et al. (25E). Peroxidase in sweet corn has been determined by Naveh et al. (28E)using a chemiluminescent procedure. Endopeptidases in malt have been extracted in aqueuous NaCl and cysteine and assayed on Azure-A hide powder or gelatin by Anderegg et al. (2E). A radioisotopic method using denatured lz5I-labeledhuman serum has been suggested by Kas et al. (I7E) for the determination of low levels of proteolytic activity in foodstuffs. Proteinaseactivities at low levels in milk have been detected by Cliffe et al. (11E)using Hide Powder Azure. Proteinases in sterile milk have been assayed by Chism et al. (9E) after incubation for 3 days and measurement of fluorescence after addition of fluorescamine. Peptidase activity in starter cultures and Cheddar cheese has been detected by Cliffe et al. (IOE)using a modified starch gel electrophoretic technique. Plant henolic enzymes have been determined by Blume et al. (3E7 by HPLC analysis of the phenolic acids formed by enzyme action. A metachromic agar-diffusion method for the determination of milk ribonuclease activity has been described by Cantafora et al. (6E). The standard method for trypsin inhibitors in soy products has been modified by Hamerstrand et al. (15E)to remove the possibility of obtaining erroneous
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high values, and Fernandez et al. (13E) have studied the relationships of trypsin inhibitors and the content of tannins and polyphenols. A method for the analysis of urease activity in soyabean products has been published by the British Standards Institution (4E).
FATS, OILS, A N D FATTY ACIDS A detailed comparison was made of methylene chloride and chloroform for the extraction of fats from food products involving samples of ten different retail foods (22F). Extracted material was midyed by GLC and it was reported that CHC13 (a suspected carcinogen) can be replaced by CHzClz(each in a 2:l mixture with methanol) without loss of efficiency. A pulsed NMR method is given ( 5 9 9 for determining lipids in food products in which up to 4% of water does not interfere and Robertson and Windham have compared results of the AOCS extraction-gravimetric method (Ai 3-75) with those obtained by NIR and NMR spectroscopy for measuring the oil content of wnflower seed (91F), finding no significant different in total oil contents. Morrison (73F)describes a rapid turbidimetric method for determining wax in sunflower seed oil wherein the oil is heated, filtered, mixed with an equal volume of acetone, chilled in an ice bath and the turbidity measured and compared against a calibration curve and a comparative study was made of the Anton Paar density meter against conventional dilatometry for determining the solid-fat index of fats and oils (;'IF). A GLC method is provided for the characterization of commercial waxes (61F)with the waxes being analyzed both before and after treatment with diazomethane (for fatty acids) or acetic anhydride (for alcohols) and Miller et al. (70F)provide a rapid procedure for extracting milk fat which correlates well with Babcock results. Drycolumn extraction methods are given for the quantitative isolation of lipids of both partially defatted and dry roasted peanuts (3F) and for the quantitative extraction and class separation (i.e., neutral and polar lipids) of lipids from animal muscle tissue (ti5F). A new spectrophotometric method was developed (81F)for determining the solid fat content (SFC) of crude palm oil, based on the different solubilities of the endogenous carotenes in the solid and liquid components of the oil, which has a 0.99 correlation for SFC as compared to that of the wide-line NMR technique and Bernard and Sims ( 1 O F ) describe an IR method for determination of total unsaturation (or iodine number) in pure, hydrogenated and partially hydrogenated oils requiring no sample weighing and requiring only about 2 min per analysis. The phenolic acids of virgin, refined, and solvent extracted olive oils were determined by reversed-phase column HPLC (24F) with values being obtained for protocatechuic,p-hydroxybenzoic,vanillic, caffeic, syringic,p-coumaric,sinapic, 0-coumaric, and cinnamic acids, and Bhuchar et al. (13F) describe a bromine titration method for on-line control of solvent extraction of whole ground-nut kernels which takes advantage of the facts that some 80% of the ground-nut oil fatty acids are unsaturated and that bromine in the presence of a mercury salt will saturate any double bonds including conjugated bonds. Based on a successful IUPAC-AOAC collaborative study, a chromatographicmethod has been proposed to assess deterioration of frying fats by measuring polar and nonpolar components separated on a silica gel 60 column (107F),with the method being adopted as official first action by the AOAC. Tyman et al. (106F)report an HPLC procedure for determining the long chain phenols and polymeric material in the phenolic lipids of cashew nut-shell liquid and a rapid column method is described for measuring the unsaponifiable matter in fatty acids ( 6 6 n with comparison made against the official AOCS and ASTM methods. A colorimetric spot test is presented by Robern and Gray (9OF)for monitoring the accumulation of oxidative products in heated oils wherein oils containing 4, 10, and 20% altered triglycerides (as determined for comparative purposes by silica gel chromatography) gave blue, green, and yellow spots, respectively, with bromcresol-green incorporated with silica gel on a slide, and analysis has been made of the unsaponifiable fraction of many vegetable oils by Lercker et al. (62F) by use of capillary GC on OV-17 of the trimethylsilyl derivatives of unsaponifiable fractions first separated by TLC. Chromatographic procedures are given for the isolation and identification of kahweol palmitate and cafestol palmitate from green coffee wherein a petroleum ether extract was fractionated by preparative normal-phase and
reversed-phaseliquid chromatography (successively)followed by final purification using AgN03impregnated TLC (58F)and Kolhe et al. (55F) report on the analysis for 3-oxotriterpenes in the unsaponifiablle matter of some vegetable fats, finding it to be present in 5 of the 14 fats examined. A rapid, simple colorimetrictest using thymolphthalein is described (56F)for the determination of acid value in oils which is reported to require only about 1 min to perform and which gave results similar to those obtained by the standard IUPAC test, Kuridu and Deb (57F) report on a column chromatographic method for determining unnaponifiable matter in fats and oils which they claim has advantages over standard methods, and the automatic determination of oxidation stability of oil and fatty products is also given wherein volatile reaction products are captured in a water trap and detected conductometricdly (36F). A procedure is presented for the analysis of oleate, linoleate, and linolenate hydroperoxides in oxidized ester mixtures by reducing the hydroperoxides, separating the resulting hydroxy esters by argentation TLC, and then analyzing the esters by GC ail their TMS derivatives (35F) and Bond et al. (18F)provide a differential pulse polarographicmethod for determining the malonaldehyde extracted from vegetable oils using 2 M HCl as supporting electrolyte. The derivative technique is used with UV spectrophotometry to measure the oxidative alteration of lipids (30F) and a TLC method is described for determining the acetone insolubles in crude and degummed rapeseed oils using chromarods followed by quantitation using flame ionization detection (298')with the results obtained for phosphatides comparing favorably against gravimetric results. Tulloch reports (105F) on the use of 13C NMR to nondestructively investigate the conjugated unciaturated acids in seed oil triacylglycerols, making structural identifications of component acids from shifts of double bond carbons and of carbons close to the double bond systems and obtaining quantitation from signal intensities. The IGC analysis of triglycerides on silanized glass capillary colunins is presented (43F,103F),mono- and diglycerides were analyzed from rape oil and lard by GC of their silylated derivatives on a glass capillary column coated with SE52 (89F),and Lainza and Slover ( 6 0 9 make use of SP-2340 glass capillary colunnns for GC analysis of the trans fatty acid content of foods, with results reported for a variety of products. A multistep TLC-GC procedure is presented for determining the triglyceride composition of olive oil ( 2 6 0 ,the mass spectrometric determination of triglycerides of selected fats by the direct chemical-ionization technique is described (95F), and Dlasgupta et al. ( 2 8 0 report on a new method for determining glyceride composition of fats by oxidation, fractionation of the derived azeleoglycerides by TLC and quantitation of the fractions obtained by colorimetry. A colorimetric microdleterminationfor peroxide values is given (6F)which incorporates aluminum chloride as catalyst, Yamaguchi reports on a sensitive and simple colorimetric method for determining fatty acid hydroperoxides with horseradish peroxidase (11IF), and Guhr et al. (44F) provide a standardized method for determining the polar fat fraction in frying fats using a silicic acid column to retain the polar fat. A simple and rapid GC method is given for the assessment of used frying oils (82F)wherein analysis is achieved on a short column packed with 3% JXR and parameters are adjusted to provide a pattern in which the dimeric est,ers emerge as a doublet peak with a retention time of about 3 min, a procedure is described for determining hydroxytyrosol and tyrosol in the polar fraction of olive oil by reversed-phase HPLC (42F),Meltzer et al. (69F) have measured the cyclic monomers formed in thermally abused soybean oils by gas chromatography after first hydrogenating the oils and then separating a major portion of the saturated components from the cyclic monomers by low temperature crystallization, Schulte (94F) presents a simple apparatus for the rapid analysis of polymerized triglycerides by gel chromatography (using a 1 m X 6 mm column of Biobeads El-X 2 and methylene chloride as the solvent/eluant), and Park et al. ( 8 3 0 provide an HPLC method for determining the hydroperoxides formed by autoxidation of vegetable oils. The GC-MS analysis of the flophemesyl (dimethyl(pentafluor0pheny1)silyl) derivatives of a series of fatty acid methyl ester derivatives is reported (40F) and Min presents a correlation of sensory evaluation against instrumental gas chromatographic analysis of edible oils (72F) reporting that flavor qualities could be correlated at 0.99, 0.98, and 0.95, respecANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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tively, for soybean oil, hydrogenated soybean oil, and corn oil. The rapid determination of mono-, di-, and triglycerides has been performed by an enzymic technique after fractionation by TLC (21F)and diacylglycerols have been measured as their labile dimethylborate esters using reversed-phaseTLC (85F). Goiffon et al. (41F) provide retention indices for the HPLC analysis of fat triglycerides, El-Hamdy and Perkins report on the HPLC determination of natural triglyceride mixtures covering the effects of column packing as well as "critical pair" separation (33F,34F),and HPLC has also been applied to the analysis of the fatty acid composition of soybean oil after first forming the p-bromophenacyl esters of the fatty acids which are then separated by gradient elution (50F).HPLC methods are reported for the analysis of triglycerides with methanolacetone as mobile phase and refractometric detection (88F), with acetonitrile-isopropyl alcohol and hexane with UV detection (46F)and with propionitrile or acetonitri1e:ethyl ether (2:l) as the mobile phase on a LiChrosorb RP-18 column (93F). Petersson et al. (87F)describe the HPLC separation of natural oil triglycerides into fractions with the same carbon number and numbers of double bonds and give results for palm oil, low erucic acid rape oil, and cocoa butter. Nimura et al. (8OF) make use of the fluorescent labeling of fatty acids with 9anthryldiazomethane in neutral methanol to obtain improved sensitivity by fluorimetric detection using HPLC for the separation and determination of geometric and positional isomers of long-chain fatty acids, the analysis of fatty alcohols and acids by HPLC as their p-(methy1thio)-benzoateesters is reported (109F) and Svensson et al. (101F)describe the analysis of geometric and ositional isomers of long-chain monounsaturated fatty aci& by reversed-phase HPLC using an "interference refractive index" detector followed by glass capillary GC. Chemical ionization mass spectrometryhas been used to identify positions of double bonds in polyunsaturated fatty acids (1OOF)and for the detection of hydroxy fatty acids in biolo ical samples using both positive and negative CI-MS in comknation with capillary GC (98F). Neissner (78F) provides a two-dimensional TLC method for the analysis of complex mixtures of partial glycerides of castor oil fatty acids on activated silica gel plates and also a technique for the preparation and TLC analysis of fatty acids after esterification with mesoerythritol (77F). A two-stage TLC method (CHC13:MeOH:HAcin a ratio of 98:2:1 followed by hexaneETOET-HAC in the ratio of 470:30:1) is presented for separation of lipid classes (169. Glass capillary GC with a FFAP coated column was used to determine isomeric unsaturated fatty acids in edible fats ( 1 1 2 9 , Dasgupta et al. (27F) report on the use of ferric chloride-methanol reagent to convert fatty acids into their methyl esters after 10 min of reflux prior to GC analysis and Wilson described a rapid GC method (11OF) for determining erucic acid in rapeseed oil in order to comply with legislation requirements. The determination of erucic acid in food oils is also effected by first separating the methyl esters on a silica gel TLC plate and locating the erucic acid fraction by spraying with dichlorofluoresceinand comparing against standards and then analyzing the fraction by gas chromatography, using tetradecanoic acid methyl ester as internal standard (108F). Meijboom and Jongenotter (68F) give a combined TLC and GC procedure for the determination of low erucic acid levels in oil after methylation with BF3MeOH with the cis-docosenoic methyl ester fraction being analyzed by GC before and after ozonolysis. Trans isomers in shortenings and edible oils were determined by IR spectrophotometry at 967 cm-l, with base line calibration achieved by use of standard methyl linoleate-methyl elaidate mixtures (63F), Marchand et al. (64F)describe complementary techniques incorporating AgN03-TLC, methoxy, acetoxymercury-adduct formation, ozonolysis, and gas chromatography for the identification of trans,trans-18:2 isomers in margarines, and HPLC is used with an infrared detector (monitoring at 5.72 ,urn) to determine free acids and mono-, di-, and triglycerides (84F). A rapid technique was developed for the determination of triglycerides according to their degree of unsaturation using mercuric acetate adducts and TLC with flame ionization detection (86F),the fractionation of triacylglycerols was accomplished for peanut and cottonseed oils by use of reversed-phase HPLC (12F) and a method is provided for the determination of esterified safflower oils using pancreatic lipase to selectively hydrolyze the acid at the 1position and then analyzing the free acids and the 2-mono174R
ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
glycerides by a combination of TLC followed by GLC (67F). Hsieh et al. (47F)have determined the saturated steryl esters and acylglycerols in wheat endosperm by direct gas chromatography on a column of 3% OV-17 on Gas Chrom Q and an automated colorimetric method is described for determining free fatty acids in vegetable oils using the flow injection analysis technique (31F). Three analyses (ATR-IR spectrometry to follow trans-isomer formation, refractive index to follow I value, and GC for fatty acid composition) were automated (17F) to follow the progress of vegetable oil hydrogenation, Mouillet et al. ( 7 4 9 report on a rapid titrimetric method to monitor the fatty acids produced by the lipolysis of milk and Battaglia et al. (8F)describe the enzymic determination of polyunsaturated fatty acids in foods by monitoring the change in absorbance at 234 nm after addition of lipoxygenase to a solution of food. Chromarods-S modified with silver nitrate was used to effect a TLC analysis of the isomeric unsaturated fatty acids of partially hydrogenated menhaden oil using flame ionization detection (96F),Scholfield reports (9ZF)on argentation HPLC of methyl esters of vegetable oils and shortenings on an Amberlite XE-284 column treated with AgN03, and partial argentation resin chromatography(Amberlyst XN-1010 sulfonic acid resin with a portion of the sulfonic acid protons replaced by silver ion) has been studied to determine the effect of silver levels on elution and separation of methyl octadecadienoate isomers ( 2 9 and used to determine saturated and mono-, di-, tri-, and tetraenoic fatty esters (IF). A new GLC method is described for the determination of cyclopropenoic and cyclopropanoic fatty acids in cottonseed and kapok seed oils by use of glass capillary columns coated with BDS or Carbowax 20M (15F) and Kint et al. (53F) report on the analysis of cyclopropenoid fatty acids by employing Raman spectroscopy. The HPLC analysis of cis and trans isomers of monounsaturated fatty acids was performed with columns treated with AgN03 (7F) and a method is given for the separation and determination of fatty acids by isotopic dilution and radiogas-liquid chromatography (9F). A method is provided for the rapid extraction of phospholipids from plant oils and then estimating them by colorimetric determination of total phosphorus (102F),Stefanov et al. report a procedure for the quantitative determination of phospholipids in sunflower seeds by two-dimensionalTLC and photometric determination of phosphorus (99F), a chromatographic method is presented for the isolation of phospholipids in peanut oils with the phosphorus being estimated by colorimetry and conversion factors provided for calculating the individual phospholipids from the elemental phosphorus (97F),and the determination of phospholipid in foods was also accomplished by a combined liquid chromatograph-automated phosphorus analyzer (51F). Biacs ( 1 4 9 describes a gel chromatographic method for fractionating sunflower and rapeseed lecithin with the fatty acids being analyzed by GC, phospholipids are determined by TLC after their column chromatographic separation from total lipid extracts (39F),and TLC is also used to determine the phospholipids of milk without previous isolation from total lipid extracts (38F) with the method described being reported to neither lyse the phospholipids nor cause any appreciable losses based on studies with phospholipid standards. A rapid and practical method is reported for the GLC measurement of the sn-1,2-diacylglycerolmoieties of natural glycerophospholipids using polar wall-coated open tubular columns (75F),a general method is given for analysis of phosphatidylcholines by HPLC after formation of the phosphatidic dimethyl esters with results given for egg (48F), Hanson et al. describe the HPLC analysis of egg-yolk phospholipidsextracted from freeze-dried material in methanol with complete separation of neutral lipids, phosphatidylcholine, sphingomyelin, lysophosphatidylcholine, and phosphatidylethanolamine being attained in 30 min (45F)and a rapid HPLC method is also reported for the determination of phosphatidylcholine in soybean lecithin (76F). Hurst and Martin (498")determine the lecithin in chocolate b HPLC after extraction with a modified Folch reagent anBthen eliminate interfering compounds with a Sep-PAK prior to chromatography, an HPLC procedure described as suitable for the analysis of phospholipids in tissue extracts is given (23F)wherein the separation is accomplished on a microparticulate silica gel column using isocratic elution and UV detection at 203 nm and a solvent
FOO13S
mixture of acetonitrile-methanol-85% phosphoric acid (1305:1.5 by volume), and Beutler and Henninger have determined lecithins in food by use of an enzymic method (1IF). A novel system for separation of phospholipids by HPLC is given wherein radioactively labeled phospholipids are separated on a column of LiChrosorb Si 60 (10 pm) with use of a two-stage elution system, with half of the eluate being passed through a flow-through radioactivity detector and the other half collected for scintillation counting (5F). A HPLC method for cholesterol in foods is given which makes use of the benzoate ester of cholesterol and a Bondapak C18column with UV detection (79F), Tsai and Hudson have analyzed 24 oxygenated cholesterols and structurally related compounds by HPLC using a silicic acid column with various mobile phases and show the effect of various functional groups on the retention volumes (104F),El-Hamdy (32F)reports on the application of HPLC reversed-phase chromatography for separating triglycerides, cholesterol, and cholesteryl esters and its application in the analysis of natural and oxidized oils, and Csiky (25.F)describes a technique for the trace enrichment and separation of cholesterol oxidation products by adsorption HPLC wherein the oxygenated sterols are concentrated on a short precolumn of Nucleosil NO2with hexane as the mobile phase and separation is accomplished on a longer column with the same stationary phase but with a hexane-propanol or hexane-butanol gradient. In an effort to provide more accurate cholesterol data for foods, Fukui et al. (37F) report on the determination of cholesterol by TLC, GC, GC-MS, and by an enzymic and a colorimetric method. A GLC procedure is described for the direct analysis of cholesterol after extraction of foods with chloroform-methanol (2:l) (52F), a biochemical method is applied to the analysis of cholesterol in fats and oils making use of the H 2 0formed when cholesterol is oxidized by cholesterol oxidase to develop a colorimetric method for its determination (20F),and Knights (54F) reports on a combined TLC-GLC method for the quantitative analysis of plant sterols. A GC method is given for the determination of 0-sitosterol in meats, soya, and other protein products ( 4 9 . Byrne et a1. (19F)report, on the determination of 0-sitosterol and 0-sitosterol-D-glucoside in whiskey by HPLC after first collecting them on a short Amberlite XAD-2 column from which they are eluted with chloroform-2-propanol (3:l) and HPLC is employed by Kashimoto et al. (113F)to determine sesamolin, sesamin, and sesamol in sesame oil.
FLAVORS AND VOLATILE COMPOUNDS A number of new bo0k.s have been recently published which are directed toward the analysis, control, and understanding of flavors and aromas and which serve as useful reference works for the flavor analyst. Among these are the 3rd Weurman Symposium Proceedings of the International Flavor Conference (74G),The Quality of Foods and Beverages (6G), which provides the proceedings of the Second International Flavor Conference held in Athens, Greece, and The Analysis and Control of Less Desirable Flavors in Foods and Beverages by Charalamboiis (5G). Food Flavors, Pt. A: Introduction, by Morton and IMacLeod (56G),Theimer’s Fragrance Chemistry the Science of the Sense of Smell (83G), and The Chemistry of Heterocyclic Compounds in Flavors and Aromas by Vernin (92G) are also useful references. Jennings and Shibamoto have provided a book on the Qualitative Analysis of Flavor and Fragrance Volatiles by Glass Capillary Gas Chromatography (37G),which contains mass spectral data as well as GC retention indices for many volatiles (for OV-101 and Carbowax 20M columns), and Kolor has reviewed the mass spectrometric analysis of various classes of flavor compounds in a variety of foodstuffs (44G). The use of closed-system vacuum distillation as a means of quantitativelg and rapidly isolating moderately volatile compounds from food for GC analysis is described by Daniels et al. ( I l G ) , advantage i s taken of the charge-transfer complexes formed with nitro-aromatic compounds by pyrazines (formed by the heat treatment of foods) to effect their TLC separation on Silica Gel G (89G),and Parliment and Spencer (62G) describe the use of simultaneous detectors (FID plus FPD detectors for nitrogen and also sulfur) combined with capillary gas chromatography for measuring specific flavor compounds in complex natural mixtures. The determination of diacetyl and acetoin by differential
pulse polarography after separation by steam distillation is reported (46G),Flanders et al. describe the application of two different trapping/ isolation, methods coupled with flame photometric GC for the analysis of the volatile sulfur coimpounds from cooked (hen) eggs (19G),and a procedure is given for the analysis of roquefortine in blue cheese and blue-cheese dressing using HPLC with both ultraviolet and eledrochemical detectors and a LiClhrosorb RP-2 column after extraction of samples with ethyl acetate (94G). A method is described (50G) in which the alkaline aroma components of Swiss Gruyere cheese are isolated by vacuum gas stripping of grated cheese samples at room temperature followed by ether extraction of the alkalinized distillates, and they are then analyzed by GC using nitrogen specific detection combined with mass spectrometry. Grandolini et al. (27G) describe a GC method for determining quassin from beverages using a column of SE 30 on Gas Chrom Q, quassinoids are determined in bitter Simiaroubacea extracts by HPLC on Radialpak C using aqueous methanol as eluant (82G),GC methods are described for the determination of volatile aromas in syrups and brown sugars, with 29 flavor compounds identified in brown sugars (24G) and also for the determination of the volatiles responsible for characteristic molasses aroma (25G),and the HPLC analysis of 5-hydroxymethyl-%furaldehyde(HMF) in caramel solution is given which is applicable to brandies or liqueurs (IG). The analysis of both furfural and HMF in brandy and honey is reported using reversed-phase HPLC on a LiChrosorb RP-18 column and UV detection at 285 nm (38G),the glycosides of liquorice (including glycyrrhizin) have been measured by Chen and Li (7G)by means of extraction in ammonia, separation using ion-exchange chromatography, and detection by turbidimetry at 530 nm after heating the eluate with HC104,and a HPLC method is also given for the determination of glycyrrhizin in foods such as soy sauce and miso (42G)wherein the glycyrrhizin was isolated with a polyamide column priior to HPLC analysis on a reversed-phase C8 column using TJV detection. Woodbury (97G) has developed a method which determines the pun ency of capsicum by use of HPLC wiith spectrofluormetric cfetection, Shankaranarayana et al. (76G) give a titrimetric method for determining the flavor strength in alliums based on oxidation of the steam distillate with chloramine-?’, TLC followed by spectrometric measurement is used to analyze for the sinapine contents of mustards (39G), Bajaj determines the capsaicin in capsicum fruits spectirophotometrically after first effecting a chromatographic separation from interfering pigments (2G),and a procedure is provided for the determination of isothiocyanic esters (applied to allyl isothiocyanate in mustard) in which the ester is fiirst converted into a thiourea and then titrated with mercuric acetate solution using a mercur or silver amalgam electrode (IOG). A combined ‘TLC-HPL: procedure is given (81G)for the determination of the main pungent principles of ginger wherein the dried and powdered root is first extracted with ethanol under reduced pressure (results are given for 12 samples including data for 6-, 8- and 10-gingerols and 6-, 8-, and 10- shogaols), Oberdieck described methods (59G) used for the isolation by steam distillation of the essential oils of 10 varieties of marjoram and subsequent separation of the volatiles obtained by column chromatography prior to GLC, GC-MS, and IR analysis, and Haut and Core (29G) provide a HPLC method for the analysis of menthol isomers which has been applied to the analysis of corn-mint (Mentha arvenis) oil. Davis and Cooks (12G) have made use of various hdS techniques to directly analyze nutmeg, taking data with both a sector type and a triple quadrapole MS-MS instrument, using the scans of all precursor ions that yield mass-selected fragment ions, to characterize groups of compounds with particular structural units, and also to pinpoint where MS-R4S spectra contained contributionsfrom more than one structural isomer. Kihara (40G)reports a spectrophotometric method for general application to the measurement of maltol in plants by extracting with methylene chloride and then forming the maltol-Fe complex by addition of FeC13,a GC method is given for the determination of the volatile phenols in soy sauce (58G),and a scheme has been developed for the characterization of the nonvolatile minor constituents responsible for the objectionable taste of defatted soybean flour (34G) by sequential HPLC analysis. The volatile flavor of defatted soybean flour has been analyzed by GC and the fractions with ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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objectionable flavor of characteristic beany, grassy, and green odors were further examined by MS and IR with 25 compounds identified and 2-pentylfuran and ethyl vinyl ketone believed to be key compounds for the beany and grassy odor (33G),Eldridge (17G)and Ohta et al. (61G)have determined individual and total isoflavone content in soybean products by HPLC, and the volatile flavor compounds of roasted peanuts have been analyzed by GC fractionation followed by IR and MS identification with a total of 131 compounds being identified (32G). The volatile flavor components of Idaho Russet Burbank baked potatoes were also analyzed by GC fractionation and IR and MS identification with 227 compounds being identified (9G),the volatile carbonyls of fresh tomatoes and tomato preparations were isolated as their 2,4-DNP derivatives and separated for analysis by TLC (63G) and by subsequent HPLC using reversed phase technique (88G),and Pyysalo et al. (67G) report a GC method for the analysis of sesquiterpene lactones from mushrooms as their trimethylsilyl derivatives on a capillary column coated with OV-101. Methods are given for the analysis of the volatiles of roasted pistachio nuts which employ GC-MS after first fractionating the volatiles into basic and neutral-acidic fractions (78G),a TLC method is provided for the analysis of pyrazines formed by peanut oil interactions with a-amino acids a t elevated temperatures (90G), and a procedure is reported for the determination of the heterocyclic flavor volatiles formed in the basic fraction of roasted mung dal by TLC and GLC (91G). Cant and Walker describe a colorimetric method suitable for the routine analysis of indole in butter and milk fat (3G)and techniques are described for the analysis of saturated hydrocarbons in foods by use of sequential column, thin layer, and gas chromatography after extraction with pentane of HC1 treated samples (14G). A capillary GC method using a Carbowax 20M column is given for the analysis of the volatiles in cold-pressed grapefruit oil with a comparison made of internal-standard and normalization methods for quantitation (96G),a GC method is provided for the determination of trans,trans-a-farnesenein samples of distilled Mexican lime oil and cold-pressed Valencia orange oil using direct injection (57G),and Mansell and Weiler (51G) report a radioimmunoassay for the determination of limonin in citrus plants. Nomilin, a new bitter component in grapefruit juice has been determined chromatographically and measured in commercial juices with concentrations found to be highest in early season juices and decreasing with fruit maturity (ranging from 1.6 to less than 0.1 ppm) (71G). Pino (65G)has developed correlations between sensory evaluations and gas chromatographic measurements of orange volatiles, finding high correlation coefficients for specific compounds such as myrcene, 2-hexanol, linalool, and a-terpineol, and Rouseff and Fisher (72G) report on the determination of limonin and related limonoids in citrus juices by HPLC on a Zorbax CN column using IPA-hexane-CH30H (12:ll:Z) as mobile phase with UV detection. The flavor volatiles of cultivated strawberries have been analyzed by GC-MS and the data obtained correlated with sensory data (the methylthiol acetate and butyrate compounds are reported for the first time) (15G),a GC method is given for measurement of furaneol in cultivated and wild strawberries, pineapples, and mangoes using a Carbowax 20M capillary column with FID detection (64G),and 4-(p-hydroxyphenyl)-2-butanonehas been determined in 39 samples of raspberries and foods incorporating raspberry flavorings by GC-MS (52G). Methods are given for the analysis of 1-(4-hydroxypheny1)-3-butanone (or raspberry ketone) in foods by a rapid TLC method on silica gel plates (23G)and by HPLC on a LiChrosorb Si 100 column (20G) and a rapid colorimetric method is reported for measuring the aroma index of steam distillates of raspberries by the intensity of the blue color formed when these distillates are treated with vanillin in concentrated sulfuric acid (45G). High-resolution glass capillary GC analysis was made of the aliphatic lactone in the aroma fraction of dates (41G) and Ismail et al. have analyzed the flavor components of canned plums (36G) and plum juice (35G) by GC and GC-MS. Chairote and co-workers (4G)have determined the volatile flavor components of apricot by GC-MS after isolation by vacuum distillation and fractionation on silica gel columns, and the GC-MS analysis of cranberries is reported with the identification of 70 compounds (30G). Reindl and Stan provide HPLC methods for determining the aldehydes formed 176 R
ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
in meat by autoxidation of fatty acids as their 2,4-DNP derivatives (69G, 70G),Lee et al. (47G) report on the analysis 6-carboxylate in of methyl-3,4-dimethyl-5,6-dihydro-a-pyran roast beef volatiles by IR, NMR, and MS, and Golovnya and co-workersdescribe methodology for the isolation and analysis of 27 volatile sulfur-containing compounds of salted and salted-boiled pork by GC with flame photometric detector (26G). A purge and trap technique combined with GC-MS is used to determine the volatile organic compounds in fish (16G),and Whitfield et al. (95G) report on the analysis of oct-1-en-3-01and (5Z)-octa-1,5-dien-3-01by GC, microreaction GC, NMR, and MS in the flavor of prawns and sand lobsters. The determination of 2-acetyl-5-bromopyrole has been made in the volatiles of cocoa butter by GC with identification made by retention time, NMR, and MS (31G), Ziegleder makes use of the measurement of methylated pyrazines formed during the roasting of cocoa (by capillary GC on a Carbowax 20M column) as a means of monitoring degree of roast (99G),and Wang reports on the analysis of trace volatile organic compounds in coffee by means of a headspace concentration technique followed by GC-MS measurement (93G). Tress1 et al. (86G)describe GC-MS methods used to analyze N-alkyl- and N-furfurylpyrroles in roasted coffee, the sulfur-containing compounds in roasted coffee have been determined by distillation-extraction, adsorption chromatography, and capillary gas chromatography (87G),a technique is given (68G) for the quality evaluation of roasted coffee through storage by quantitative trace analysis of aroma components using GC-MS, and Toth (84G, 85G) describes GC methods for the separation and analysis of phenol fractions from smokehouse smoke. A rapid, automated enzymic method is reported (98G)for the determination of alcohol by using flow injection analysis which is suitable for beverages, Sponholz and Wuensch (80G) provide an enzymic method for the determination of dihydroxyacetone in the presence of glycerol in alcoholic beverages, and GC analysis for aldehydes in (German) wines is described (79G). A procedure for the gas chromatographic analysis of volatile esters in wines is presented (77G) alon with data for various commercial wines, Schreier reports (75G7 on the determination of additional volatile constituents of red wine by GC and GC-MS techniques, and a headspace GC method is iven for the determination of safrole in flavored beverages ?73G) such as vermouth. Postel and Meier (66G) present a method for the GC determination of 2-acetolactate, 2-acetohydroxybutyrate, diacetyl, pentane-2,3-dione, and acetoin in grape must and wine, a HPLC method is given for the determination of acetaldehyde in wine as its lutidine derivative (60G)and a reversed-phase HPLC method is reported for the determination of @-asarone(a constituent of calamus oil) which is used as a flavoring (e.g., vermouth) and which is regulated in much of Europe (55G). An enzymic assay for acetaldehyde is provided (54G)for grape juice and wine, Martin et al. (53G)report on the determination of congeners in alcoholic products by GLC using GC-MS as a confirmation technique, and Leppanen and co-workers (49G)describe the headspace adsorption (on Chromosorb 101) followed by GC analysis for the determination of thioacetates and other volatile sulfur compounds in alcoholic beverages. Lehtonen has developed a GC method for analyzing phenols in alcoholic beverages as their 2,4-dinitrophenyl ethers using glass capillary GC and EC detection (48G),a microwave spectroscopic method is provided for determining methanol in wine (43G),and a combined LC and HPLC method is given for the analysis of carbonyls from beer at the parts-per-billion level after collecting them as their 2,4-DNP derivatives (28G). A rapid HPLC method is reported for the determination of 2-furaldehyde and hydroxymethyl-2-furaldehyde in alcoholic beverages using a reversed-phase technique (22G),Frattini et al. (21G)describe the LC fractionation and GC-MS analysis of the volatile components of mountain wormwood essential oil, and Etievant (18G)describes the analysis of the volatile phenols in wine by GLC and GC-MS after solvent extraction and column chromatographic fractionation on a DEAE-cellulose column, Dickenson (13G) provides a headspace capillary GC method for the determination of dimethyl sulfoxide in malt, wort, and beer and Cheney et al. (8G)report on the analysis of ethanol in solution by alternating current tensammetry, reporting satisfactory results for vodka but indicating that substances having surfactant properties (such as
FOODS
fusel oils in distilled spirits) gave interferences.
JDENTITY This section is concerned with analysis of pure foods, detection of foods in foods, and indicators of quality. Pattern recognition techniques have been proposed by Leegwater et al. (44H) as a means of differentiating French and German brandies by the use of four flavor components as characteristic variables. Chinese alcoholic beverages have been analyzed by Ng et al. (55H) using gas chromatography and ratios of higher alcohols to methanol were found to be useful criteria for identification. The use of liquid scintillation counting of 14C has been suggested by Martin et al. (50H) for the differentiation of synthetic ethanol from ethanol of fermentation. Total alkaloid value has been suggested by Hadorn (21H) as means of estimating cocoa mass in cocoa containing products. Theobromine and caffeine contents of chocolate and milk chocolate have been reported by Herrmann et al. (22H) and of various natural and red Dutched cocoas by De Vries et al. (12H). The use of gas chromatographic triglyceride analysis has been reported by Fincke for the examination of cocoabutter-substitute fats (18H) and for cacao butter (19H). Sterols and met hylsterols in cocoa butter and cocoa butter substitutes havt? been studied by Homberg et al. (25H) and qualitative distinctions have been made. Foreign fats in cocoa butter have been detected by Dick et al. (13H) by GC examination of the urisaponifiables for steroids. Interpretation of triglyceride patiterns by GLC has been proposed by Padley et al. (57 M) as a means of determining the amount and type of “cocoa butter equivalents” added to chocolate. The degree of roasting of cacao has been estimated by Ziegleder (85H) by GC determiriation of methylated pyrazines. An HPLC method for the determination of 5-hydroxymethyl-2-furaldehyde and caffeine in coffee and chicory extracts has been described by Smith (73H),and the detection of the furaldehyde can be used to distinguish coffee from coffee-chicory extracts. Changes in the volatiles of roasted coffee during storage have been studied by Radtke-Granzer Triglyceride GLC has been used by Timms (76H) et al. (61M. to detect as little as 5% of nonmilk fats in milk fat. A rapid detection procedure for cows milk in goats milk has been described by Mitchell (52H) using electrophoresis on cellulose acetate. Cows milk in sheep and goats milk has been detected by Krause et al, (40H) by the use of isoelectric focusing on polyacrylamide gels containing urea. A polarographicmethod for mercapto groups has been used by Lechner et al. (43H) to detect whey powder in skimmed milk powder. The ammonia content of milk has been determined by Soederhjelm et al. (7113)using an ammonia electrode, and the ammonia content may be used as an indicator of biological deterioration or aging. Casein and whey-protein containing casein have been differentiated by Kabus et al. (33H) by amperometrictitration of the SH and 5% groups. Total protein, casein, and whey protein in dairy products have been determined by Douglas et ei. (17H) by the use of the phosphorus to nitrogen ratio. Phosphatidylcholinecontent determined by TLC and GC has been suggested by Liem et al. (45H) as a specific basis for egg-yolk determination in food products. Egg content in pastry has been determined by Kaffka et al. (34H) by the use of NIR spectrometry. Sweet almond oil has been differentiated from blends with apricot and peach-kernel oil by Salvo et al. (6710 using TLC and GC of the sterols. Argemone oil has been determined by Shenolikar et al. (68H) in edible oil by TLC, and argemone oil and rapeseed oil have been detected in mustard seed oil, also by TLC, by Datta (11H). A TLC procedure has been used by Sengupta et al. (70H) to detect palm oil in vanaspati. Combined column and gas chromatography have bleen applied by Kapoulas et al. (37H) to the determination of seed oik in olive oil. Tallow in lard has been detected by Juarez et al. (32H) by gas chromatography of the fatty acids. The use of gas chromatographyfor the assessment of used frying oils has been described by Paradis et al. (581fl by measurement of the dime, triglyceride content. Protein patterns obtained om cooked and frozen crab meat have been shown by Krzynowek et al. (41H) to differentiate between genera by the use of polyacrylamide gel isoelectric focusing. An index using biogenic amines has been found by Karmas (38H)to provide a quality indicator for seafood. Ethanol has been described by Iida et al. (27H) to be useful as a quality index for albacore and for other raw fish
(28H). The volatile components of raw tuna have been clorrelated by Human et al. (26H) with the quality of the fkh. Total volatile basic nitrogen, determined after steam distillation, has been fouind to increase with deteriorating quality by Billon et al. (5H). Detection of high-fructose corn syrup in apple juice by mius spectrometric I3C 12C analysis has been submitted to collaborative study y Doner et al. (15H) and the method adopted first action. Analytical techniques have been described by Brause et al. (6H) for the verification of the authenticity of apple juice. Components of apricot pulp halve been determined and tabulated by Fuchs et al. (20H). Analytical data on blueberries, blackberries, and elderberries, includingamino acids, has been reported by Kuhlmann (42H) for the expressed juices of these berries. The papers included in a symposium on citrus nutrition and quality have been published by Nagy et al. (54H). Flavonoids and citrus quality have been discussed by Rouseff (6623. Analytical data on Israeli orange amd grapefruit juices have been reported by Cohen (823, and Wallrausch (78H) has determined and tabulated data on grapefruit juices. The use of spectrometric and fluorometric examinationof orange ‘uice and orange pulpwalsh to detect mixtures of the two has been described by Petrus et al. (59H). Data on trace metals in orange juice have been summarized by McHard et al. (46H). Pattern recognition techniques have been used by Bayer et al. (4H) to select five elements (Ba, B, Ga, Mn, and Rb) in orange juice concentrate which can be used as indicators of geographical origin. A collaborative study has been carried out by Doner et al. (16H) of the mass spectrometric procedure for the detection of high fructose corn syrup in orange juice; the method was adopted first action. Tagetes extract in orange oil has been identified by Wild et al. (80m by the examination of the carotenoid pigments. Literature data have been compiled by Wrolstad et al. (82H) on free sugars and sorbitol in fruits and on sugars, sorbitol, nonvolatile acids, and free amino acids in fruit juices (83H). Elementary contents of 15 standard fruit and vegetalble materials have been listed by Daniel (IOH). Free and total amino acids in citrus juices and strawberry and blackberry mashes have been determined by Tateo et al. (75H). Twenty-four fresh fruits have been analyzed by Richmond et al. (63H) for sugars and sorbitol by HPLC. Electrophoresis techniques including gel electrophoresis and methods for the identification of cereal varieties by examination of the grain proteins have been discussed by Wriglley et al. (81H).Data on minerals and protein contents in hard red winter wheat cultivars have been obtained by Dikeman (14H). Electrophoresishas been used by Joudrier et al. (31H) to detect the presence of barley in hard wheat flour paste by the characteristic amylase polymorphism in the two species. Rice or buckwheat flour in wheat flour has been determined by Ohara et al. (5CiH) by electrophoresis of the proteins. Electrophoresis of the prolamins of wheat, rye, barley, and oats has been used by Hohlfeld et al. (24H) to detect those grains in flours and foods. Mineral contents of a selection of cereals and baked products have been determined by Mahoney
b
WH).
Three percent of added sugar has been detected in maple products by Carro et al. (7H) by stable carbon isotope ratio. Sugar-adulteratedand natural honeys have been differentiated by Zagaevskii et al. (84H) by the color produced with camphor solution and by the amylase activity. Further testing to confirm high-fructosecorn syrup adulteration of honey when certain hotope ratios are obtained by the AOAC test has been recommended by White (79H). Polarographic suppression of the 0 peaks during the determination of fructose has been found by Marek et al. (49H) to be a means of detecting the addition of invert sugar to honey. Electrophoreses has been used by Armstrong et al. (223 to determine isolated soybean protein in raw and pasteurized meat products and by Valas-Gelleiet al. (77H) to determine milk and soy proteins in meat products. Gel permeation chromatography has been applied by Iijima ‘29H) to the analysis of soyabean pvotein products in foods. A rapid chromatographic m e t h d using modified circular pager chromatography ha13been developed by Jebsen et al. (30.H) for the detection of foreign proteins in minced meat. Soybean protein in meat products has been determined by Crimes et al. (9H)by analyzing the soluble peptide for serine and by an immunosorbent assay procedure. The enzymatic analysis ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL
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of galactose in soya has been applied by Morrissey et al. (53H) to the quantitation of soya proteins in soya-meat blends. Linear gradient polyacrylamide gel electrophoresis has been applied by Babiker et al. (323 to the detection of horse meat in beef. Enzyme staining of isolectric focusing gels has been used by King et al. (39“) to detect buffalo, horse, pig, or kangaroo meat in beef. Feather meal in protein concentrates has been determined by Maestro et al. (47H) by TLC of the amino acids. The amino acid content of collagen from various fabrics has been determined by Polzhofer (60H)by amino acid analysis and the information applied to the analysis of the collagen coating on synthetic sausage skins. Tryptophan and hydroxyproline contents of sausages have been suggested by Sokele et al. (72“) as indicators of quality. Biogenic amines have been described by Slemr (69H) as potential chemical indicators of meat quality. Patterns obtained by HPLC and electrophoresis for protein supplements such as @-casein, @-lactoglobulin,and soyabean protein have been described by Reimerdes (62H) as distinctive and useful for detecting these additiveg. Proteins of vegetable and animal origin have been differentiated by Ring et al. (64H) using disk polyacrylamide gel electrophoresis. These same protein types have been examined by Kaiser et al. (36H) by isoelectric focusing in agarose gel. Proteins in binary raw meat mixtures have been examined by Kaiser et al. (35H) using the same technique, and mixtures could be analyzed. Soya, egg albumin, and wheat gluten have been separated by Rizvi et al. (65H) by sodium dodecyl sulfate gel electrophoresis. Soya proteins in food have been determined by Hitchcock et al. (23H) using an enzyme-linked immunosorbent assay. Analytical data showing differences in mineral and proximate analyses content between mechanically deboned and hand-deboned broiler parts have been obtained by Ang et al. (1H). A staining technique using iodine has been used by Sreedharan (74H) to distinguish papaya seed from black pepper. The stable-isotope ratio technique has been used by Martin et al. (51H)to determine natural vanillin in adulterated vanillin extract, and the vanillin to potassium ratio permitted differentiation between vanilla extracts from Java and Madagascar.
INORGANIC An extensive review of trace element determination via spectrophotometric techniques was published by Marczenko (844, within which food applications were considered. Mirza ( 9 0 4 discussed the properties of 4-benzoyl-3-methyl-1phenylpyrazolin-5-one as a broad spectrum extraction reagent for metals. A novel test strip for Cu, Zn, Cd, Ni, and Co ions was prepared by Tanaka et al. (1294 with 2-(2-thiazolylazo)-p-cresol reagent in a PVC film. Blake (114 presented a large review on sample preparation before atomic absorption spectrometry (AAS). Atomic spectroscopy literature from July to December 1981 was cited by Lawrence (794. The hydride generation technique as applied to AAS methods was reviewed by Godden et al. (524. Verlinden et al. (1354 prepared a review concerning hydride-AAS approaches. Several different spectrometric methods such as AAS, ICP emission, X-ray fluorescence, and NAA were covered when Pickford (10 8 4 reviewed trace diet components. An apparatus that automated the time and temperature control aspects of wet ashing was used by Nakajima et al. ( 9 9 4 to expedite the removal of organic material from polished rice samples. Schramel et al. (1194 described a Teflon tube holder for accelerated decomposition at 160 OC and 10-12 bar pressure. A stepwise procedure for dry ashing sugar was given by Saito et al. (1184. Techniques for the direct introduction of solid samples into a carbon tube for AAS were shown by Grobenski et al. (564. Brooks et al. ( I 7 4 reviewed the instrumental determination of arsenic, covering 1971-1981. Cottenie et al. (314 discussed plant analysis for many metals including arsenic by ICP plasma emission and listed the effect of using different spectral lines and operating conditions. Jones et al. ( 7 1 4 evaluated a procedure for separating elements by ion exchan e before sample direct or hydride generation ICP determination. inlet for an ICP spectrometer that permitted hydride introduction along with usual ionic solutions was presented by Wolnik et al. (1385). Hahn et al. ( 5 9 4 employed a cqld condensation trap to concentrate hydrides before ICP emission, achieving an order of magnitude better sensitivity than direct introduction. Some changes in graphite furnace gas purging and addition of EDTA to the sample solution allowed
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Uthus et al. (1344 to report lower interferences in arsine detection. A one-piece design apparatus was shown by Everson (455) for arsine generation in AOAC method 42.005. Liddle et al. (815) listed o timal conditions for generating arsine with sodium borohy&ide for AAS. Brooke et al. (164 distilled inorganic arsenic first from HC1 or chelated it to separate it from organic arsenic before hydride AAS in their studies on fish. Maher (834 used ion exchange to separate inorganic from methylated arsenic species in clams and then determined the fractions separately by reduction to arsine and graphite tube AAS. Kurosawa et al. (775) examined shark tissue for arsenobetaine, separating it by an HPLC connected directly to an ICP plasma spectrometer set to 193.7 nm. Burkhardt ( 2 0 4 described his temperature-controlled apparatus for wet ashing foods and the diethylammonium-diethyldithiocarbamate chelation steps before flameless AAS of As, Pb, Cd, Hg, and Se. Mueller at al. ( 9 6 4 used wet digestion and the same extractant for these elements in a graphite furnace AAS method. Arafat et al. ( 7 4 used wet acid-peroxide digestion before hydride generation and flame aspiration AAS for As, Al, Fe, Zn, Cr, and Cu in plant samples. An AutoAnalyzer was used for the reduction of As and Se to hydrides with flameless AAS by Agemian et al. ( 2 4 . Holak (645) reported a collaborative study on closed-system digestion followed by ASV and both normal and hydride AAS for metals including As, Se, Pb, Cd, Cu, and Zn. A review on selenium trace methodology for food was written by Hofsommer et al. (624. Hahn et al. (584 illustrated how condensation of the hydride improved selenium AAS methodology for vegetable analysis. An interference in the direct determination of Se by flameless AAS, namely, HC1, was discussed by Hofsommer et al. (634 who recommended C U ( N O ~addition. )~ Vijan et al. (1364 described the inhibitory effect of other metals in Se hydride generation and they advised using 7.5 M HCl to complex those metals first. Inui et al. (674cleaned up acid digests of tea and liver by ion exchange before Se hydride generation into a graphite tube furnace. Reamer et al. (1144 compared several wet and dry ashing methods for Se losses, following retention with 7bSe. Several food materials were analyzed by Rigin (1164 who used extraction of Se’” with 4-nitro-0-phenylenediamine in toluene, generation of the hydride from this solution, and detection of Se by atomic fluorescence in a helium stream. 82Sewas added by Reamer et al. (1154to samples before wet digestion and complexation with this reagent and then ratioed to 8oSe after GC-MS. Raptis et al. (1124 followed wet and dry digestions with the eneration and filtration of elemental Se, which was measured y X-ray fluorescence. The procedings of the AOAC “Symposium on Analytical Methodolo for Lead in Foods” were compiled for publication Sampling and homogenization to improve by Boyer data uniformity for lead in canned food were discussed by Suddendorf et al. (12w). Rains et al. (1114 and Koirtyohann et al. ( 7 4 4 all presented the advantages of using a L’vov platform in electric furnace AAS for lead analysis, and also recommended NH4H2P04to level remaining matrix effects. Dobeka (334 reported results of analyses conducted by operators of different experience levels and concluded that routine trace lead analysis was reliable if attention was given to contamination control. Miles (894 compared studies involving ASV and furnace AAS lead measurement to assess reliability for infant formula analysis. Mergey et al. (884 increased sample throughput by conducting wet digestion and ASV in a single tube without Metexchange reagent. Lead and cadmium were precipitated to preconcentrate them before AAS measurement of a sulfated ash solution in a method by Gorshkov et al. (534 applied to grain and potatoes. Kruse (765) wet-ashed fish in Teflon beakers with loose covers preceding furnace AAS. Poldoski (11OJ)found that treatment of his graphite furnace tube with Mo and La solutions gave more even atomization of lead and cadmium from fish digests. Caristi et al. (235) mixed 50% NH4N03solution with citrus juices before introduction into the electric AAS furnace for Pb, Cu, Fe, and Zn analysis. Nembrini et al. (1014 gave the advantages of using a “Lumatom” digesting solvent before AC polarographic measurement of tin, lead, and copper. This technique was further discussed by Dogan et al. (404. A collaborative study of a method for Pb and Cd using ASV after dry ashing was reported by Capar et al. (225)and adopted official first action (AOAC). Mrowetz (945) determinted Pb,
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Cd, and Cu by A8V after dissolution of an oxide ash in H2SO4 solution and then added HC1 to do Sn. Debacker et al. (364 found they could measure Sn and Pb in the same stripping voltammogram in a methanol-2-propanol-HC1 electrolyte. Good agreement with other tin methods was found by Dabeka et al. ( 3 4 4 when they aspirated food acid digests into a N20-C2H2AAS flame with added K+ ion. A comparison of ICP plasma emission and AAS was made by Ishii et al. (684 in studying Mn, Fe, Co, Ni, Cu, Zn, Cd, and Sr in shellfish, who founcl matrix effects on calibration slopes for ICP. A method for multielement measurement in oils by direct aspiration of a hydrocarbon solution into a plasma spectrometer was given by Dijkstra et al. (374. A modification of the AOAC procedure for mercury in fish which used a hot water bath open-tube digestionwas reported by Duve et al. (4.24. Callum et al. ( 2 1 4 employed subtilisin enzyme treatment to liquify tissue before extraction, cleanup-derivatization, and EC GC of methylmercury residues. Margler et al. (854 separated methylmercury by TLC before pyrolysis and cold vapor absorption measurement. Milk products were combusted with oxygen in a sealed bomb before liberation of Hg vapor and AAS in the work of Narasaki (1005). Dumarey et al. ( 4 1 4 pyrolyzed samples on quartz filter paper, collecting Hg on gold-coated sand which, after a second adsorption-desorption from gold, was measured as cold vapor in a sitream of Nz. Hirano (614 discussed high values given by combustion-gold desorption methods vs. acid digestion. Levels of mercury in tuna fish were established by Ahmed et al. (45') who use pressure acid-digestion and then used H202with W radiation to destroy soluble or anics before ASV from a gold (electrode. A colorimetric methoffor mercury in fish was presented by Gras et al. (554 that titrated a complex with di-p-naphthylthiocarbazoneat 510 nm to the same intensity as a known standard. A generation flask design was given by Suddenorf et al. (1214 to introduce cold Hg vapor into either an ICP plasma, AAS, or UV monitor. Ebdon et al. (434 increased the atomic fluorescence detectability of Hg vapor 10-fold by sheathing the stream in argon. Detection limits of low picogram per milliliter were reported for Hg by Tanabe et al. (1234 when the emission from a helium microwave plasma was monitored. Results for CLI,Mn, and Zn in beef were found to be in agreement with rished solutions when Mohamed et al. (914 directly aspirated homogenized tissue into air-acetylene AAS. Harnly et al. (604 described a technique of wavelength modulation wherein less sensitive lines were utilized to extend calibration ranges by orders of magnitude for Cu, Fe, K, Mg, Mn, Na, Zn, and Ca. Kobayashi et al. ( 7 3 4 managed to extend sensitivity for zinc analysis to below 1 ng/mL by correlating carbonate dehydrase activity with concentration. Zn in milk was determined by Chauhan et al. (265) who formed a complex with 4-(2,3-dihydroxy-4-pyridylazo)benzenesulfonic acid or its 5'-chloro derivative. Andoh et al. (64 digested food samples in acid in a microwave oven before AAS for Zn and Cu. Clement ( 2 9 4 reported overcoming interferences in Mg analysis by using N20-C H2 flame AAS. Karapetian et al. (724 found that copper couli be determined after ashing milk without interferences using 6-phenyl-2,3dihydro-l,2,4-triazine-3-thione. Iron in beer and beverages was analyzed by Hoyle et al. (655) with the colorimetric reagent 2,4,6-trisi-4-(4-sulfophenyl)-2-pyridyl-l,3,5-triazine, whose complex absorbed at 607 nm. Mortatti et al. (934 adapted the 1,lO-phenanthroline reagent to a flow injection method and could determine iron at rates up to 180 samples per hour. O'Laughlin et al. (1055) separated Fe2+,Ni2+,Ni2" and Ru2+complexes of this reagent by HPLC of the paired: ions with alkanesidfonic acids. Garza-Ulloa et al. (504 studied other metals for possible interferences in the measurement of iron in beer with ferrozine reagent. Gouda et al. (545') studied N-substituted phenothiazines as indicators for redox titrations with ceric sulfate of Fe2+,MeV, VIv, and organic species. A procedure for Ni in food, among other samples, was given by Pihlar et al. (1094 who, after wet-ashing, performed voltamme try on the nickel-dimethylglyoxime complex deposited ton a mercury drop. Eivazi et al. (444 utilized the catalytic action of Mo on the KI-Hz02 reaction to determine this metal in an AutoAnalyzer apparatus. Before graphite furnance AAS, Ni et al. (1025) extracted Mo from acid digests with N-phenylbenzohydroxamic acid. Lyons et al. (824 extracted Mo from plant acid
digests as quinolin-8-01complex in CHC13before dissolution in acid and ICP emission. A method that could detect a nanogram per milliliter of Mo by differential pulse polaragraphy (DPP) was given by Chatelet-Cuzin et al. ( 2 5 4 who optimized electrolytes. Vanadium in foods was determined colorimetrically by Bermejo-Barrera et al. ( 9 4 using 8hydroxyquinoline in isoamyl alcohol. Agrawal (34 showed that absorption at 555 nm after complexation with 2-methoxy-N-m-tolylbenzolhydroxamicacid could determine V in fruits, vegetables, etc. Chelnokova et al. (274 demonstrated that coprecipitation with antipyrine dye salts could recover traces of Co, Ma, Cu, and Zn from excesses of other elements before spark source emission spectrometry. Boron in plants and soil when measured by ICP emission was shown to correlate well with the Azomethine H method by Gestring et al. (514. A study of dry ashing conditions to prepare vegetables for Na and K analysk was made by Rowan et al. (1174. Patti et al. (1074 fused shellfish samples with Na202,precipitated hydroxides and, after ion exchange, measured technetium-99 by p counting. Abukawa et al. ( 1 4 succeeded in separating cesium-137 from rubidium on a Duolite C-3 column in a method for soil and food samples. Fluoride in plants could be determined on alkaline fused ash solutions with a commercial electrode after Eyde (46J) masked aluminum with citrate. Fluoride traces in salt samples could be measured by Kokubu et al. ( 7 5 4 with an electrode after concentration on a ZrIv-loaded cation exchange resin. Allegrini et al. (54 looked at total diet composites for iodine content by neutron activation analysis after removing C1 iinterference by combustion and adsorption. Black et al. (10J discussed the effect of light on the stability of response of an iodide electrode. Milk was analyzed for total iodine by DPP after ashing and oxidation of iodate in a method by Curtis et al. (324. In their use of an iodide electrode for milk measurements, Lacroix et al. (785) found that not enough SH groups were formed to interfere from conventional pasteurization. Yamanobe et al. (1394 combusted samples in oxygen and converted iodine to 3-iodo-2-butanone which was subjected to ECGC. McCurdy et al. (874 coprecipitated iodine-131 with CUIin assaying milk for that element. A modified method for bromide entailing conversion to 2-bromoethanol was presented by Stijve (1204 who shortened the analysis time. Momokawa et al. (925) analyzed fish-jelly for bromine by titrating bromate formed after oxidizing the ash. Leuenberger et al. (804 separated nitrate and bromide ions on NH2-HPLCpackings using 210-nm UV detection. Nagayania et al. ( 9 7 4 extracted bromate from bread, adsorbed it on DEAE-Sephadex A25, and determined it by TLC after elution. Watanabe et al. (1374 determined bromate in bread by ion chromatography, utilizing column separation and concentration trapping to remove C1-, PO:-, and SO?- interference. Twenty anions, including NO3-, NO2-, and SCN- were separated by Tanabe et i d . (1244 using paper chromatography who measured NO3- in vegetables. Methods for nitrate anid nitrite in meat were reviewed by Pallotti et al. (1064. Frouiin et al. (494 also presented a review of NO; and NO, methods in meat. Brugel(184 reviewed methodology for nitrates and nitrites in edible plants. Terada et al. (1314 measured NO3in vegetables by separating water extracts on Zipax SAX iin 0.05 M KH2P04buffer and monitoring absorbance at 210 nm. Thayer et al. (1324 compared a similar separation to chemical methods for NO, anti NO, and found HPLC more sensitive. Tateo et al. (1304 looked at meat extracts by an ion chromatographic method and found that high C1- amounts required removal as an interference. A GC method using EC detection was given by Tanaka et al. (1284 wherein nitrite in milk was reacted with 1-hydrazinophthalazine. Tanaka et al. (1274 also reported on this reaction being applied to other foods with GC flame ionization detection. Nitrate in vegetables was reacted with 2-sec-butylphenol and measured at 418 nm in a procedure by Tanaka et al. (1264. Both nitrite and nitrate in foods were determined by Tanaka et al. (125J) who combined both aforementioned reaction methods, dewith pentafluorobenzoic rivatized the 4-nitro-2-sec-butylphenol acid, and performed GC analysis after cleaning up other organic volatiles that interfered. Noda et al. (1045) employed HPLC separation of the hydralazine-nitrite reaction product and monitored reversed-phase column effluents with UV absorbance or fluorescence. Rauter et al. (1134 used reaction with p-cresol, steam distillation, and colorimetry to determine ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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nitrate in vegetables. Chikamoto et al. (285) favored reacting nitrite in food extracts with p-bromoaniline and CuCl with subsequent EC GC analysis for the 1-bromo-4-chlorobenzene formed. Nitrite in milk powders by chemiluminescence detection was compared to colorimetric measurement by Doerr et al. ( 3 9 4 who found no significant difference in results. Doerr et al. ( 3 8 4 analyzed meats for nitrite content by chemiluminescence, Griess reagent, and DPP, finding comparable precision but superior sensitivity for the former method. A collaborative study on cheese was reported by Castegnaro et al. (245) for GC-chemiluminescence methodology for N-nitroso compounds. Fox et al. (474 discussed chemical effects of meat ingredients and sample treatments, e.g., HgClZ, charcoal, and Carrez reagents as they affected Griess, chemiluminescent, and DPP NO2measurement. Fox et al. ( 4 8 4 had covered the effect of ascorbate and C1- on nitrite determination by Griess reaction. Bousset ( 1 4 4 noted the effect of HgClz added before Griess reaction and recommended determining free NOz- without it. Berger et al. ( 8 4 also discussed interferences in NO3- and NO2-analysis due to the complex composition of meat curing mixtures. A new method for natural carbon-14 content of foods was published by Mueller e t al. ( 9 5 4 who absorbed COz from combustion in NaOH, formed BaC03, liberated C02 into 1-aminopropan-2-01, and then counted the resulting 1,3bis-(2-hydroxypropyl)ureaby liquid scintillation. Nissenbaum et al. (1034 applied a water analysis procedure to orange juice to measure oxygen-18 and deuterium. Blouin et al. ( 1 2 4 succeeded in using a commercial blood gas analyzer to quantify C02 liberated from still wines. Yuen et al. (1404 ashed oil samples in an oxygen bomb before determining total P with a molybdovanadate reagent. Daun et al. ( 3 5 4 compared O2 bomb, perchloric acid, and saponification digestions as well as colorimetry, AAS, and emission methods to determine P in Canola oils. Nakai et al. (98J determined pyrophosphate in blanching solutions by stabilizing turbidity with manganous reagent and reading a t 625 nm. Phytate from pea meal was extracted with TCA solution by Cosgrove (308 and selectively eluted from an anion exchange column to separate it from other phosphate esters. Hydrogen peroxide traces in milk were detected by Matsubara et al. ( 8 6 4 who overcame a protein turbidity problem when complexing with Ti(IV)-4-(2pyridy1azo)resorcinol reagent. Iwaida et al. ( 7 0 4 compared three methods for residual H202 in foods and judged the 4-aminoantipyrine color reaction the most reliable. Improvements in this color test were described by Ito et al. (694 who extended detection of peroxide down to 50 ppb. Toyoda et al. (1334 used an oxygen electrode apparatus to measure peroxide through liberation of oxygen by catalase. Total cyanide in cassava was determined by Ikediobi et al. ( 6 6 4 by incubating with linamarase, adding alkaline picrate, and heating to produce a color absorbing a t 490 nm. Hahn et al. ( 5 7 4 discussed two instrumental dissolved oxygen-in-beer analyzers, comparing their results to the indigocarmine method. Buckee (194 presented a scheme for concluding if hops had been sulfured that detected S and SO2 after adsorption on copper gauze and liberation for titration measurement. Boland et al. ( 1 3 4 gave ways of preparing food samples for pH measurement, reporting collaborative data.
MOISTURE A useful reference for a better understanding of the behavior, state, and interactions of water in food systems is provided by Rockland and Stewart (15K). Zuercher and Hadorn report on the determination of water by the Karl Fischer method for approximately 90 different foodstuffs, providing comparative data and recommending the most favorable Karl Fischer variant for each food ( 2 0 ,and Jones et al. (4K)have optimized the automatic Karl Fischer titration for the determination of moisture in grain. Commercial vapor pressure thermocouple psychrometers were adapted for rapid water activity (Aw) measurements for foods in the 0.99 to 0.60 range using a two-step procedure (19K) with analysis time estimated to be 4 to 8 min. Methodology is described for determining unfreezable water in protein suspensions by low-temperature NMR (2K) and NMR spectroscopy has also been applied to studying the internal movement and binding of water in raw and roasted coffee and also of grounds (16K). Muffett et al. (9K)make use of differential scanning calorimetry to measure the unfrozen and free water in soy proteins, 180R
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and Tsai and Ockerman provide comparisons of three techniques for measuring the water binding properties of meat (18K). A method has been proposed for measuring the water hydration capacity of plant protein material by the AACC (13K),and use is made of the proximity equilibrium cell for rapid determination of sorption isotherms (6K),this technique has been applied to determining the Aw of intermediate moisture foods, and results show that it is applicable over the Aw range of 0.40-0.98 (7K). Multon et al. (1OK)describe a fast method and equipment with which the activity of water in foods can be estimated in 5-10 min and Northolt and Heuvelman provide a simple, inexpensive control method (11K)for testing the water activity of foods which depends on the visible liquefaction of salt crystals with appropriate, specific Aw values. Inverse gas chromatography is used to provide water sorption isotherms for sucrose and glucose a t very low levels (17K)and a spectrophotometric method using a blue dextran 2000 solution was devised ( I K ) to measure the amount of water sorbed by the starch granules in suspension (the dextran being too large to penetrate the starch granules as the granules sorb water). A method to measure the water holding properties of dietary fiber under physiological conditions using suction pressure across a dialysis membrane is given (14K)wherein solutions of compounds of known osmotic potential were used to create a suction pressure across the membrane containing the fiber sample, thus permitting the determination of the water holding capacity of the fiber at each suction pressure. Oshima et al. (12K)report an electrical conductivity method for estimating the total solids in milk, and near-infrared photoacoustic spectroscopy is applied to the determination of moisture in some solid materials (3K). Mladek and Beran (8K) discuss sample geometry, temperature, and density factors in the microwave measurement of moisture and provide examples of calculations and experimental data for the moisture measurement for selected foodstuffs and agricultural products. The application of microwave on-line moisture monitoring of driers is described for low hydrated materials (Le., 6-14% H20) with the microwave meter having the capability for providing effective control of a drier in an industrial plant (5K).
ORGANIC ACIDS Refinements made to an enzymic method for acetate in wine and juice by McCloskey (40L) obtained official first action AOAC status. Trombella et al. (62L)used formic acid saturated carrier gas to improve the gas chromatography of acetic acid during direct wine injection. Isshiki et al. (22L)determined propionic acid in bread by direct GC of a dimethylformamide-formic acid extract. Overall organic acids were measured by conductivity after adding excess imidazole or 2-amnopyridine in the work of Okayama et al. (43L). Markwalder (36L)reviewed enzymic methods for lactic acid in cheese. Ayroulet-Martin et al. (3L) applied Ling’s milk method for lactic acid to meat, calibrating to compensate for imcomplete extraction. Littman et al. (34L) analyzed egg products for tricarboxylic and related acids including P-hydroxybutyric using capillary GC after cleanup and methylation. Dorsett et al. (15L) investigated the usefulness of a Selectrode for citrate activity in plant samples. A fourfold sensitivity increase was reported for an NADH enzymic technique for citrate in vegetables by Girotti et al. (18L). Ester-bonded citrate in starches was determined by spectrophotometry and titration by Klaushofer et al. (26L). Down to 4 kg of citramalic acid in vinegars could be found in TLC method of Valdehita et al. (66L). Sponholz et al. (58L)gave their method to determine 2-hydroxyglutamates in wines and musts. Kozukue (29L)separated a-keto acids as DNPH derivatives on an Lichrosorb Si-60 HPLC column in 10 min. Small amounts of oxalate in plants were determined by Turner (63L) by measuring COz via GC after decarboxylation. D(+)-Malate in fruit juices was determined a t the parts-permillion level using D-(+)-malate NAD oxidoreductase in the work of Knichel et al. (28L). Klein (27L)separated the organic acids of sauerkraut brine using isotachophoresis. Fukuba et al. (17L)described their leading and terminating electrolytes useful to separate acids in shellfish by isotachophoresis. Droz et al. (16L)used cation exchange for cleanup before separation of juice and wine acids on reversed-phase HPLC with 225 and 210 nrn monitoring. Brugman et al. (9L)separated aromatic
FOODS
and substituted cinnamic acids, among others, with silica adsorption HPLC. Fruit juices were analyzed for tartaric malic and citric acids by reversed-phase HPLC by Bigliardi et al. (6L)who used refractive index detection. Several reversed-phase and ion exchange columns were investigated for carboxylic acid separations by Buslig et al. (11L)for application to different fruit, and food samples. A separation scheme utilizing column, thin layer, and gas chromatographic stages of analysis was described by Tonogai et al. (61L) for fruit-derived foods. Marsili et al. (3715) quantified dairy product acids by monitoring and eluent from an HPX-87 column at 220 and 275 nni. Rajakyla (46L)monitored gluconic acid formation in fermentation liquors, introducingthe sample onto cation exchange HPLC columns after filtration. Ushijima et al. (65L) utilized a commercial carboxylic acid chromatograph to measure soy sauce acids as postcolumn colored derivatives. Malic acid in wines was measured in an automated enzymic method reportled by Lonvaud-Funel et al. (35L). Many derivatives of hydroxycinnamic acid in cranberries were elucidated by Marwan et al. (39L) who employed UV and visible spectrophotometry as well as paper and liquid chromatography but no hydroxycinnamic-quinic esters were found. Okamura et al. (42L)related the phenolic cinnamates in white wine to the quality, using reversed-phase HPLC and 280-nm detection. Hydroxycinnamic-quinic esters in fruits were separated and measured as TMS ethers on glass capillary columns and also by direct HPLC in a study by Moeller et al. (41L). Schulz et al. (55L) investigated spices for hydroxybenzoic and hydroxycinnamic acids with both packed and capillary column CC of ‘I‘MS derivatives. Tanabe et al. (59L) monitored their HPLC eluent at 315 nm to achieve more sensitive detection of total ferulate in rice bran oils. Several phenolic glucosides of fruit including 1-0-hydroxycinnamylP-D-glucosides were reported on by Reschke et al. (47L) who did two-dimensional TLC and also HPLC of acetylated derivatives on silica gel. Natural benzoic acid levels in dairy products down to 0.4 ppm were analyzed by Richardson et al. (4%) with GC of the methyl ester. Dewaele (13L)reviewed the analysis of hops and beer for bitter acids employing HPLC techniques. Axcell et al. (2L) reported good correlation of conductometricmeasurements to direct near-IR measurement of hop a-acids. Hautke (2OL)avoided emulsions in extracting a-acids with polyethylene strips contacting the solvent layers. Verzele et al. (671,) monitored 270 nm in their HPLC method for beer bitter acids to minimize response differences of separate a-acids. IJndesirable humulinic acids were separated by gradient reversed-phase HPLC in model system experiments by Schulze et al. (56L). Lance et ai. (31L) analyzed hop extracts on Spherisorb 5 ODs, adding citric acid to the mobile phase to reduce column adsorption. Several HPLC systems were investigated by Dewaele et al. (14L)for sepwration of six iso-a-acids before choosing an ion-pair mode. Belleau et al. (51,)showed the dimer of gallic acid to be UMnatural to beer in a method utilizing normal-phase HPLC. Off-flavors in beer due to trihydroxyoctadecenoic acids were measured by GC after diazomethane reaction and silylation in work by Yabuuchi et al. (72L). The analysis of brandies for phenol compounds was reviewed by Puech (45L). Somers et al. (5715)discussed the interference of SO2in staridard methods for phenolics in wine. Roston et al. (51L) reviewed HPLC methods for monocyclic phenolic acids. These authors (50L) also showed the utility of electrochemical detection at +950 MV to monitor HPLC effluents for phenolic acids in beer and whiskey. The same authors (52L)then expanded the scope of oxidative detection with a dual electrode detector. Kr gier et al. (30L) investigated oilseed for free, esterified, anJbound phenolic acids by TMS-GC. Wilson (69L) first extracted phenolics from apple juice on Sephadex LH-20 before subsequent, normal- and reversed-phase HPLC separations. Lea (33L) also studied these compounds employing a shift in pH to enhance his separations on the column. Roberts et al. (49L) noted formation of compounds similar to thearubigens in stored tea, using HPLC techniques. Total phenols in plant material by the Prussian Blue method were evaluated by Budini et al. (IOL)who commented on interferences and applied the measurement to strawberries. Tannins from plants were bound to hemoglobin to precipitate them in a photometric method by Schultz et al. (54L). Billot (7L) oxidized phenolics from vegetables with copper(I1) to determine them with
spectrophotometric relationships. Beer polyphenols were isolated and separated by HPLC by Kirby et al. (25L) in studies on haze formation. A scheme to separate complex phenolic mixtures was described by Kaluza et al. (23L) using Sephadex CL-6B and Sephacryl 5-200 with continuous monitoring of effluents. Their method for p1,ant phenolics was used by Horvat et ill. (21L) to analyze instant tea and pecans wherein both methylation and TMS reactions were carried out before GC or GC-MS. Wood smoke used for meat curing was examined by Borys (8L)for nitroslo and nitrophenols using HPLC after an XAD-4 cleanup. Wittkowski et al. (70L) fractionated the mono- and dihydroxyphenolsbefore GC-MS of trimethylsilyl derivatives in an investigation of beechwood smoke concentrate. Phytic acid in rapeseed meal was examined by Uppstrom et al. (64L) with color development after phytase treatment. Tangkongchitr et al. l(60L)differentiated phytate phosphorus, inorganic P and P not precipated by Fe(+3) by different treatments before colorimetry. Saio et al. (53L)isolated phytic acid from vegetable proteins by iron precipitation before hydrolysis and phosphorus determination. Latta et al. (32L) determined phytate in whole rapeseed by color decrease wiith an FeC1,-sulfosalicylic acid reagent. Cosgrove (12L) aliao discussed his work in the determination of phytate in flour and ground field pea seeds. Graf et al. (19L) used HPLtC separation for phytate in wheat bran after initial resin column isolation. O’Neill et al. (44L) measured phytate in cereals by Fourier NMR spectroscopy of phosphorus-31. Glycyrrizic acid from licorice extracts was detected at 254 nm after separation on a C18 HPLC column by Bell (41,). Martin et al. (38L) compared a TLC to an HPLC separation for glycyrrizic acid and found the latter superior. Vora (6815) analyzed licorice for glycyrrizic acid salts in a collaborative study of an HPLC method requiring less than 15 min time. The use of p-bromophenacyl bromide to derivatize sterioside and rebaudioside for ti secondary HPLC separation after initial TLC was detailed by Ahmed et al. (1L). Abscisic acid from potatoes was methylated by diazomethane before GLC in woirk by Karavaeva et al. I(%%). Cows milk was analyzed for the presence of hippuric acid using color development with 13dimethylaminobenzaldehydein a study by Wolfschoon-Pombo et al. (71L).
NITROGEN Methods for total nitrogen, protein nitrogen, and its connponents as well as other nitrogen-containing compounds are continuously being studied and improved as indicated in this period’s literature. A reference method for total nitrogen in meat and meat products using the Kjeldahl procedure has been issued by the British Standards Institution (IOM). Studies on the use of titanium dioxide catalyst in Kjeldalhl determinations for meat and meat products have been carried out by Stamm et al. (109M) and as catalyst for the automatic KjelFoss instrument, by Williams et al. (128M); and botch authors found this catalyst suitable. A similar test on oilseed samples by Davidsoii (19M) has indicated good agreement between Kjeldahl and KjelFoss using titanium oxide catalyst. Various catalysts for Kjeldahl have been compared by Ugrinovits (116M) who obtained good results on various foods with the copper sulfate-potassium sulfate catalyst. A procedure for the quantitative determination of pure protein in meat products has been described by Kaltwasser et al. (6611.0 which used Kjeldahl determination of residual nitrogen after removal of nonprotein nitrogen. The automated KjelF’oss has been found applicable to meat products by McGill (85M). Improved sensitivity for colorimetry of micro-Kjeldahldigesits has been achieved by Nkonge et al. (9OM) by modifying thie reagents and reaction conditions for the Berthelot reaction. Nessler’s reagent has been used by Van Ginkel et al. (12OM) for the determination of ammonia in plant digests by continuous flow analysis. Sodium hypobromite has been used in a potentiometric titration for nitrogen in meat products by Schillak (104M) arid by Von Lengerken et al. (125M). Thie coulometric titration of proteins in milk products has been described by Brauner et al. (9M) using electro-generated bromite. Protein in meat has been determined by Cipriani (15M) by distillation firom sodium sulfate solution and titration of the distillate with hydrochloric acid; results are correlated with the Kjeldahl method. Dye binding with Amido Black ANALYTICAL CHEMISTRY, VOL. 55, NO. 5, APRIL 1983
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FOODS
10B has been used by Liuzzo et al. (79M) to determine protein in floc-producingsugars and by Bruhn et al. (12M)using C.I. Acid Orange 12 to determine protein in frozen dairy desserts. A method for the determination of cresol red index in oilseed residues has been published by the British Standards Institution (11M). Immunoturbidimetry has been applied to the determination of proteins in foods by Gombocz et al. (40M). Proteins in fish or meat meals have been determined by Wright et al. (130M) by low-resolution pulsed NMR and by Rutar et al. (99M)and O’Donnell et al. (91M) by magic-angle sample-spinning carbon-13 NMR. Heating a food sample with aluminum to form aluminum nitride followed by complexometric determination of the aluminum has been used by Vdovenko et al. (121M) to determine total nitrogen in food products. Near-infrared spectroscopy has been compared with dye binding by Biston et al. (8M) for estimating protein in oat groats, both procedures compared satisfactorily with Kjeldahl. Descriptions of the use of NIR for protein and other consituents in meats have been published by Hauser et al. (47M) and Kruggel et al. (73M). The applications of NIR analysis for protein in grains have been discussed by DeGroen (20M) for barley and malt, by Hruschka et al. (55M) for ground wheat, by Williams et al. (127M) for hard wheat, and by Krischenko et al. (72M) for the analysis of grain and grain products. Tkachuk (115M)has applied this procedure to the analysis of whole wheat kernels. Conversion factors for protein in milk have been calculated by DeLange et al. (21M),for food and agricultural samples by De Rham (23M),and for soybean protein products by Morr (86M). A procedure for the assessment of protein digestability has been described by Gauthier et al. (34M), using enzyme hydrolysis and simultaneous dialysis. A review of procedures for the detection and estimation of collagen has been published by Etherington et al. (28M). A method for the determination of a suitable value for the colla en to protein ratio in chopped meats has been described by jailler (92M) using a modified hydroxyprolineprocedure. Trinitrobenzene sulfonic acid and ninhydrin methods have been compared by Clegg et al. (16M) for the assessment of protein degradation in cheese, and the TNBS method was preferred. Unreduced glutenin has been extracted from wheat flour with sodium dodecyl sulfate by Danno (17M). The use of ion-exchange resins has been suggested by Satyanarayana et al. (103M) as an efficient means of extracting proteins from oilseed flours. Ultra-thin-layer electrophoresis has been applied by Georg et al. (37M,38M) to the separation of legume seed proteins. Polyacrylamide gel electrophoresis has been described by Lauriere et al. (75M) for the analysis of cereal prolamins and by De La Vigne (22M) for the analysis of cheese proteins and peptides. High-resolution gel chromatography has been shown by Rutschmann et al. (IOOM) to separate protein fractions on a preparative scale. Bovine skim-milk proteins have been analyzed by Dimenna et al. (25M)using high-performancegel-permeation chromatography, and Barth (5M) has chromatographed hydrolyzed plant proteins by using a high-performance sizeexclusion technique. Size-exclusion HPLC has also been applied by Diosady et al. (26M) to the characterization of whey proteins. Reversed-phase HPLC has been used by Hancock et al. (45M)for the analysis of peptide and protein mixtures, and improved peptide separations were obtained by deactivation of the hydroxysilyl groups on the column (46M). Dipeptide mixtures have been analyzed by Lin et al. (78M) by ion-pair HPLC and identified by gas chromatography-mass spectrometry. The different ratios of sulfhydryl/disulfide groups in whey protein and a-casein has been used by Mrowetz et al. (87M) to determine whey protein in mixtures. Quantitative isoelectric focusing has been applied by Munroe et al. (88M) to the separation of wort and beer proteins. Rattenbury (95M) has edited a book on amino acid analysis. Two-dimensional TLC and HPLC have been described by Barcelon (4M) as a means of separating free amino acids as their 5-dimethylaminonaphthalene-1-sulfonyl derivatives. HPLC has also been used by Camerlynck et al. (14M)for the determination of free amino acids in vegetable tissues as the phenylthiohydantoin derivatives. The free amino acid pool of the potato has been analyzed by Golan-Goldhirsh et al. (39M)and y-aminobutyric acid and ornithine were positively identified by GC-MS. A method for total a-amino acids in orange juice has been described by Drawert et al. (27M) using the reaction with ninhydrin and titrimetric determination of 182R
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the carbon dioxide produced. High-temperature short-time hydrolysis has been compared with long-time moderate-temperature hydrolysis for foods by Lucas et al. @OM) who found the two procedures equivalent. A procedure for pretreating all amino acids with sodium hypochlorite has been developed by Ishida et al. (63M) so that proline and hydroxyproline may be determined with the other amino acids by HPLC of the phthalaldehyde derivatives. Reversed-phaseHPLC has been used by Kozukue et al. (70M) for the analysis of DNP derivatives of amino acids. Dansyl derivatives of amino acids from food hydrolyzates have been determined by HPLC by Khayat et al. (67M) and Hughes et al. (57M) who use postcolumn reaction after HPLC. High-performancethin-layer chromatography has been used by Yang (133M) to determine 20 amino acid phenylthiohydantoin derivatives in 1 h. A review of the various isotachophoresis methods for amino acids and peptides has been written by Holloway et al. (51M). Photometric determination of lysine, methionine, cysteine, and tryptophan after enzymic release has been described by Hob (52M). Sulfur amino acids in protein hydrolysates have been determined by Mackey et al. (83M) by reversed-phase chromatography of the Dns derivatives. Oxidized sulfur amino acids have been separated by Raymond et al. ( 9 6 m by ion exchange chromatography. An arginine decarboxylase plug flow reactor has been utilized by Valle-Vega et al. (118M)to measure L-arginine, and the same authors (119M) have described an arginase-urease electrode for the same determination. Betaine in sugar and wine has been determined by Vide et al. (122M)by liquid chromatography. A stopped-flow method for the determination of cysteine and reduced glutathione has been described by Inouye et al. (61M) based on the reaction of the acids with 5,5’-dithiobis(2-nitrobenzoic acid). Thiols have been separated by Nakamura et al. (89M) by anion exchange chromatography and postcolumn derivatization with o-phthalaldehydeand taurine. Specially purified L-methionine y-lyase has been used to determine L-cysteine by Tanaka et al. (113M),methionine interferes. Monosodium lutamate in foods has been determined by rapid HPLC by bporns (108M). Methods for available lysine include an Llysine enzyme electrode described by Skogberg (106M), an automated enzyme-photometric procedure by Holz (54M), a rapid dye-binding procedure with C.I. Acid Orange 12 by Hurrell et al. (59M),the use of the guanidination reaction by Maga (84M),and fluorimetric assay by Goodno et al. (41M) using o-phthalaldehyde and P-mercaptoethanol. Lysine and nitrogen have been measured by Gill (36M) using infrared reflectance, and good correlations with conventionalmethods obtained. Lysinoalanine has been determined by Fritsch et al. (30M), in foods by use of an amino acid analyzer after hydrolysis, and detection with ninhydrin. Other methods for lysinoalanine include HPLC which has been described by Wood-Rethwill et al. (129M) and an amino acid analzyer technique with fluorimetric detection by Fritsch et al. (31M) for both lysinoalanine and 2,3-diaminopropionicacid, and a method by Ishida et al. (62M) for lysinoalanine and lanthione using gas chromatography after esterification. Direct photometric determination of methionine and cyst(e)ine in enzymic hydrolysates has been described by Holz (53M). Gas chromatography has been used by Apostolatos et al. (2M) for the determination of methionine in proteins and plant materials. The determination of methionine with L-methionine y-lyase has been described by Tanaka et al. (114M). Fluorometry has been used by Jones et al. (64M) to determine 3-methylhistidine in meat products after hydrolysis and fluorescamine treatment. Selenocystine, cystine, and cysteine have been determined by Grier et al. (42M) by cathodic stripping voltammetry. Methods for tryptophan include direct fluorescence or fluorescence after reaction with formaldehyde which has been described by Steinhart ( I I I M ) , colorimetry with an iron chloride-copper chloride mixture suggested by Hu et al. (56M), and spectrophotometry and HPLC which have been compared by Devries et al. (24M). The effect of variations in hydrolysis techniques on the determintion of tryptophan has been examined by Lucas et al. (81M). A creatinine-specific enzyme electrode has been described by Guilbault et al. (43M) using creatinase. Primary and secondary amines in marine organisms have been determined by Lin et al. (77M) by conversion to the “dabsyl” derivatives and HPLC after reaction with dinitrofluorobenzene. Aliphatic secondmy amines have been determined by Bellati et al. (7M)
FOOClS
by HPLC after reaction with dinitrofluorobenzene. Glass capillary as chromatography has been described by Hamano et al. (44bfor the detection of secondary amines in foods after formation of benzenesulfonyl chloride derivatives. Amines in pure-milk bacteria cultures have been determined by Hladik et al. (49M) by TLC after formatipn of the 2,4dinitrophenyl derivatives. Volatile amines in wnes have been detected by Daudt et al. (18M) by gas chromatography with a nitrogen detector after distillation and derivatization with trifluoracetic anhydride. Careful attention to conditions for extraction has been described by Kim (68M) as providing an improved method for the determination of trimethylamine and trimethylamine oxide. Trimethylamine in egg has been determined by Hobson-Iprohock @OM) by GC after freezedrying. An improved method for the analysis of trimethylamine in fish has been described by Bullard et al. (13M) who recommend the cold method of extraction to help eliminate interferences. Three methods for volatile bases in fishery products have been compared by Gallardo et al. (33M) and problems due to sample hydrolysis noted. Biogenic amines have been determined by Zee et al. (134)in beer by automated ion exchanger, by Peckaiiek et al. (93M), in cheese and fish on an amino acid analyzer, by Hurst et al. (60M), in chocolate by HPLC, and in wine by HPLC by Froehlich et al. (32M). This technique has also been applied by Scudamore (I05M) to the determination of 2-aminobutane in potatoes. Gas chromatography has beein used by Yamamoto et al. (132M) for the analysis of putriescine, cadaverine, spermine, and spermidine in foods after reaction with ethyl chloroformate and by Staruszkiewicz et al. ( 1 1 O M ) to the determination of putrescine, cadaverine, and histamine using their perfluoropropionyl derivatives. An automated fluorimetric method for histamine in fish has been proposed by Luten (82M). Histamine has also been determined in fish by Rubach et al. (98M) by capillary isotachophoresis, and by Volk et al. (124M) by HPLC of methanol extracts. Methods for histamine and tyramine in dairy products have been described by Suhren et al. (112M) using fluorometric detection. Tyramine in fermented food products has been determined by Yamamoto et al. (131M) using gas chromatography, by Santos-Buelga et al. (102M) using sand column chromato raphy and fluorometry, and by Kostyukovskii et al. ( 7 1 3 using TLC of the didansyl derivative. Tyrosine has been determined in potatoes by Samotus et al. (101M)using a modified Millon's reaction. Aromatic amines in synthetic food colors have been determined by Hunziker et a1 (58M) using HPLC. A method for ammonia is cheese after deproteinization has been described by Behririger et al. (6M), and four methods for determining ammonia in meat roducts have been studied by Gerhardt et al. (35M). Methofs for caffeine using HPLC' have been described by F'errara et al. (29M) and applied to decaffeinated coffee by Lehmann et al. (76M) for coffee and caffeine containing foods using extraction, clarification, and UV measurement, by Ballassat-Millet et al. (3M) for tea and cola using HPLC, and by
