(5D) Fujimoto, M., Nakatsukasa, Y., Anal. Chim. Acta 26, 427 (1962). (6D) Higashuira, hl., Kagaku to Kogyo (Osaka) 36, 153 (1962). (71)) I,esigang, l f . , Herht, F., Mikrochim. Acta 1962,327. (811) ?vlcNutt, X . S., Maier, R. H., ANAL. CHERI.34, 276 (1962). (9D) Van der Reyden, A. J., van Lingen, R. 1,. M., 2. Anal. Chem. lS7, 241 (1962). Inorganic Analysis (IF:) Albaugh, E. W., Buhlert, J. E., Pearsnn, R. M.,ANAL. CHEM.35, 153 (1963). (2E) Andersson, 1,. H., Arkiu Kemz 9, 223 i1962). lop, J. A , , BuU. N . J . Acad.
\ -
I
I z v . Akad: .Yauk
Arm. S S R ; Khim: AYa~rk15, 216 (1962). (6E) Edge, R. A , , Anal. Chim. Acta 28,
278 (1963).
i7Ei Fritz. J. S.. Garralda. B. B.. Talanta 10. 91 11063l (8E)'Green, H., Metallurgia 65, 305 ~
(1962). (9E) Guillon, A,, Colonomas, S I . , Sauvagnac, R., Radiochim. Scta l, 89 11963). (1OE) Hibbits, J. O., Talanta 10, 181 (1963).
1E) Hirano, S.,Mieuike, A , , Ida, Y., Bunseki Kagaku 9, 423 (1960). 2E) Hirano, S., Mizuike, A., Ida, Y., Kokubu, N., Japan Analust 10, 326 (1961). 3E) Ishibashi, M., Nippon Kagaku Zasshi 83, 295 (1962). (14E) Jarman, I,., Manolitsis, E., Matic, M., J . S . African Inst. Mining Met. 62, Pt. 2, 773 (1962). (15E) Katsura, T., Bunseki Kcgaku 10, 1207 (1961). (16E) Kressin, I. K., Waterbury, G. R., ANAL.CHEM.34.1598 (19621. (17E) O'Connor, 'J. J.,' U'einer, J. R., Rubin, B., Ibzd., 35, 420 (1963). (18E) Pietri, C. E., Wenzel, A. W.,Ibzd., 35, 209 (1963). (19E) Ryabchikov, D. I., Borisova, L. V., Gerlit, Y. B., Zh. Analit. Khim. 17, 890 (1962). (20E) Schafer, H. N. S.,ANAL.CHEM. 35, 53 (1963). 121E) Toribara. T. Y.. Predmore. C.. ' Hargrave, P. A,, Talanta 10, 209 (1963): (22E) Wish, L., ANAL. CHEM. 34, 625 (1962). (23E) Zacharaisen, H., Beamiash, F., Zbid., 34, 964 (1962). Organic and Biochemical Analysis ( I F ) Fenton, J. C. B., Clin. Chim. Acta 7, 163 (1962). (2F) Funasaka, W., Kojima, T., Fujimura, K., Japan Analyst 10,374 (1961). (3F) Kamp, W., Klijsen, J. B., Ruward, R. H., Pharm. Weekblad 97, 889 (1962).
(4F) Kopecky, A . , Chem. Listy 56, 1033 (1962). (5F) Krampitz, G., Knappen, F., J . Chromatog. 5, 174 (1961). (6F) Mehnke, K. H., Zhid., 7, 86 (1962). (7F) Nikonovich, S. D., Dokl. Akad. S a u k Uz. S S R 20, 28 (1963). (8F) Pignard, P., A n n . Bid. Clin. 20, 325 (1962). (9F) Semenov, A. D., Ivleva, I. N., Datsko, V. G., Gidrokhim. Materialy 34, 138 (1961). (10F) Street, H. V., J . Chromatog. 7, 64 (1962). (11F) Tomlinson, R. V., Tener, G . M., J . Am. Chem. SOC. 84, 2644 (1962). (12F) Tompsett, S. L., Acta Pharmacol. Toxicol. 18, 414 (1961). (13F) Watanabe, H., Xippon Kagaku Zasshi 83, 51 (1962). Ion Exchange Papers (1G) Alberti, G., Cagdioti, V.,Lederer, M., J . Chromatog. 7,242 (1962). (2G) Ossicini, L., Ihid., 9, 114 (1962). (3G) Sherma, J., Talanta 9, 775 (1962). ( 4 G ) Sherma, J., Cline, C. W.,Ibid., 10, 787 (1963). ( 5 G ) Street, H. V., Clin. Chim. Acta 7, 226 (1962). Miscellaneous Procedures and Techniques (1H) Gal, 0. S., Intern. J . A p p l . Radiation Isotopes 13, 304 (1962). (2H) Vassiliou, B., Kunin, R., ANAL. CHEM.35, 1328 (1963).
Inorganic Microchemistry Philip W . West, Coates Chemical laboratories, Louisiana State University, Baton Rouge, la.
I
to assess the progress of inorganic microchemistry. From the standpoint of classical techniques, inorganic microchemistry presents an almost boring succession of routine developments. If appraisal of the field i 4 to include such techniques as activation analysis, coulost'atic methods, electron probe., internal reflection spectromet,ry, etc., then this is indeed an esciting period. .\fter careful consideration, however, even the developments in clasqiral areas can be reviewed with considerable enthusiasm. .\fter all, these are areas where spectacular advances in theories and techniques can hardly be espected at this stage. These are the fundamental operabions that have stood the tests of time, and sound contributions can do little more t,han make good methods better. What may seem to be a relatively minor modification or improvement may prove to be a critically important advance for the man fared with special problems a t the laboratory bench. The hulk of this review is devoted to clas,~iealmirrochemical met'hods. No tlistinrtion is made between microanalysis and trace analysis because the absolute quantity of material under T IS RATHER DIFFICULT
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study is of the same order of magnitude and the philosophies of approach are similar, even if the techniques involved may differ widely. To maintain proper perspective, appropriate commonts will be included pertaining to specialized techniques such as atomic absorption spectrometry and coulostatic methods of analysis. For more critical evaluations of such techniques, the reader is referred to the accompanying reviews that deal in more detail with these methods. There can be no doubt in the mind of anyone who follows the literature of chemistry regarding the interest in microchemistry. I n all of analytical chemistry, the great preponderance of research is in the field of highly sensitive methods. The increased impmtance of specific, selective, and sensitive methods and, of course, the increased use of automatic methods are noted when applications of analytical chemistry are observed. Particularly in the area of special problems, the great demand for mirrochemical procedures is noted. hppro\imately 4,000 references were considered in the preparation of this review. Many interesting contributions were omitted in a n attempt to present a
summary that would show the trend in the field without burdening the reader with all the details. The review is continuous from that published in 1962 (167) and extends through December 1963. .1 number of excellent reviews have appeared during the past two years. Benedetti-Pichler (20)reviewed progress in qualitative inorganic analysis, and Maurmeyer contributed a companion review of quantitative inorganic methods (107, 108). Claassen discussed inorganic trace analysis from the standpoint of methods of separation and concentration, together with common methods of measurement (48). Special problems, such as the purification of reagents and the choice of blanks, are pointed out. The discussion by West (166) of the analytical significance of coordination chemistry deals primarily with considerations important in the field of microchemistry. The Birmingham Symposium of 1962 in honor of Professor Fritz Feigl provided an outstanding medium for the presentation of a wide variety of contributions in the field of inorganic microchemistry. Proceedings of the symposium should certainly be con-
sulted by anyone interested in this field ( 1 7 2 ) . Special attent’ion is directed to the lecture by Feigl (66)in which progress in inorganic and organic spot test analysis through the application of specific, selective, and sensitive reactions is evaluated. Ijelcher and West (19) discussed the applications and implications of specific, select’ive,and sensitive reactions. General discussions of interest include the comments by H3gedus (82) regarding the terms “microchemistry” and “microanalysis.” Like many others, he feels that trace analysis is a special field, and he present:; a n interesting argument to *how t h a t it is not really a microchemical method. Roos ( I39) discussed the limit of detection of analytical methods and introduced the concept of risks. He suggested that the analyst may define the limit of detection in terms of the errors that may be associated with the presenct: of impurities or of the risk of concluding t h a t the impurity is absent when it is not. Determination of potentiometric end points was discussed by Hahn ( S I ) . Review of the analylical behavior of micro amounts of chromium (24) includes a number of aspects of general microanalysis t h a t are of interest. .-i contribution by Hofstader summarizes the progress in the determination of physical constants using reduced-scale techniques (86). Neeb (122) reviewed recent developments in the field of trace analysis, part’icularly the use of inverse polarography a r d voltammetry. He pointed out that these methods can be used for the preconcentration of traces of met&, as wel. as for the purposes of estimation. His discussions concern various electroanalytical techniques, including the tylies of electrodes, cells, applications, and procedures that are encountered. Procedures which yield two to three orders of magnitude increase sensitivity ov(:r conventional polarographic and voltctmmetric methods are described. Interesting discussions of ultramicroanalysis have appeared. .Uimarin and Petrikova ( 2 ) discussed qualitative and quantitative methods for ultramicroanalysis under the microscope. They described chromatograpliic and electrolytic separations and illustrated the apparatus used. They also described appropriate potentiomet!ric and amperomet,ric titrations. Lltramicroscale potentiometric and amperometric titrations were described also by Helbig (85), who presented a general discussion of various aspects of ultwnicroanalysis (84).
h paper by Grimaldi and Helz (80) provides a summary of 1 he sensitivities to be obtained by spectrographic, radioactivation, flame-photometric, and various “wet” methods in t r x e analyses for 74 elements. -1 number of reviews
appeared dealing with special techniques or specific areas; these will be mentioned in appropriate sections of this review. APPARATUS
Special equipment introduced for ultramicrochemical measurements includes an electrode titration assembly (22) and a phototitrator (241). An Hshaped cell with a probe microglass electrode was described by Bush (4%). Other contributions include description of a simple microburet (87) which operates by surface tension of the titrant in the buret tip and comments on microestraction equipment ( S T ) , microelectrolytic apparatus ( % ) , filtration apparatus (38), 11-glass microhalances (65), and comparison spot plates (148) useful for seniiquantitative determinations and for increasing the detection limits of spot tests. A simple appaiatus for liquid-solid estractions was described (63) and the design of automatic trace analyzers was discussed (123), with emphasis on continuous analyzers for such things as oyygen, carbon dioxide, sulfide, chloride, iodide, and hydrogen ion concentrations. I n a general review of developments in microchemical equipment, Francis emphasized new inrtrunients to be used for automatic operations (67). ORGANIC REAGENTS
Development of new reagents is fundamental to the progress of inorganic microchemistry. Even more than the introduction of new techniques or the construction of new apparatus, the availability of a variety of reagents provides flexibility in practically all of the methods for conditioning reactions and making critical measurements of identity or amount of substance. Essentially all developments in this area are related to organic reagents. Belcher (15) discussed a number of new selective and sensitive organic reagents and described different approaches used in the sysbematic search for new analytical reagents. The significance of such research is well illustrated by the studies of Delcher, Ramakrishna, and West (1 7 , 18),who found that 4-(2-pyridylazo)resorcinol serves as a selective and sensitive color reagent for niobium(V). Although the reagent is not specific for niobium, interferences can be eliminated by masking the offending ions. Lassner also proposed a selective test for niobium (97). Niobium, when treated with hydrogen pyroside and heated with methykhymol blue, produces an intense blue coloration. Although there are interferences, the masking action of disodium 1,2-diaminocyclohexanetetrh-acetate permits detection of niobium in the presence of commonly associat,ed metals.
An excellent’ summary of the considerations important in the esaniination of potential spectrophotometric reagents was provided by West (1W ) , who gave two detailed examples of how the systematic approach may be applied. Dziomko and Dunaevskaya also reviewed the approaches used to develop chelating ligands for various analytical applications (59). Berg and Alam (21) synthesized coordination polymers that form insoluble compleses with various metals. The value of organic reagents is illustrated further by the work of Lot,t and his associates (99), who pointed out that 2,3-diaminonaphthalene permits the determination of selenium gravimetrically at the milligram level, spectrophotometrically at the niicrogram level, and fluorometrically in the submicrogram range. Again, masking agents are used to increase selectivity; this important aspect is discussed in more detail in another section. T h a t organic reagents need not be specific or even selective is emphasized by the growing importance of masking techniques. Furthermore, it is highly desirable in many cases to have nonselective reagents. For example, BockWerthmann (28) searched for a general color reagent suitable for the location of ions in paper chromatography. After investigating 283 organic reagents, he recommended tetrahydrosyquinone as a general color reagent for such applications. Likewise, Pollard, Xickless, and Burton recommended ethanolic fluorescein as a spray reagent for anions (131). Reviews of organic reagents and their applications in industrial analysis (16, 152,177) serve as a useful guide for those who wish to follow developments in this area. Approsimately half of the references that deal with inorganic microchemistry employed organic compounds either as primary resgents or as masking or conditioning agents. Further reference to individual reagents is in discussions of specific procedures.
SEPARATIONS
Microanalysis more than any area of chemistry is dependent on the availability of separation methods. I n many cases where instrumental finiqheq are used for detection or meawrement, conventional separation techniques are employed. Spectrophotometric methods, spot testq, and titrimetric and gravimetric procedures, hoir ever, often include separation steps that are so qimple and 30 efficient that the operation involved may pass unnoticed by analysts who are uninitiated in the niceties of iuch methods. >\la.;king is particularly convwient and efficient (although it is not strictly a separation method in the physical VOL. 36, NO. 5, APRIL 1964
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sense), and usually the addition of a masking agent results in nothing more than elimination of an interference. There is no separation of phases, nor any other physical evidence that reactions have occurred. Only a few seconds of time are involved and no special technique is required. Feigl has always been masterful in his use of masking as a means of obtaining specificity or selectivity. Usually, but not always, masking involves the addition of complexing ligands that sequester the interfering substances. An exception is the use of sulfamic acid to eliminate the oxides of nitrogen interference in determinations of sulfur dioxide (17 4 ) . Selection of such agents still remains essentially an art. The only compilations of such agents were those which appeared in previous inorganic microchemistry reviews until Cheng's discussion ( 4 6 ) )which deals with masking agents and lists practically all such agents that have found use up to this time, was printed. In the discussion of the analytical significance of coordination chemistry, West (166) included a comprehensive table of ions, together with masking agents that have been employed in eliminating their interfering effects. Masking action of some 20 complexans in many tests employed in qualitative inorganic analysis was studied by Hoyle, Sanderson, and West (88); Yamagnchi and Ueno studied the use of &aminoethylmercaptan (179) and P-mercaptopropionic acids as masking agents in chelatometric titrations (180). Unithiol (116), cysteine (as), and thioglycolic acid (134) were also studied as masking agents useful in complexometric titrations. Another simple but effective means of concentrating or separating test substances is that of the ion exchange beads used by F u j h o t o , Fukabori, and Nakatsukasa (7&73), Reactants are concentrated on the surface of an ion exchange bead, and separation or enhancement of sensitivity is obtained by the reaction that takes place on the resulting surface. A modification of this technique was proposed by Blasius and Brozio (26),who noted that 4-hydroxypyridine-2,6-dicarboxylic acid forms complexes with different ions which have widely varyinq stabilities a t high p H value. Condensation of this reagent with resorcinol and formaldehyde produces an ion exchange resin which can be employed in column separations of yttrium and various alkaline-earth ions. Ion exchange-modified cellulose paper was used for the qeparation of metals (91), and Schulek and his associates employed oxycellulose for the isolation of trace metals (142-144). Coprecipitation is a standard technique used to gather traces Metal sulfides and hydroxides are particularly 146 R
ANALYTICAL CHEMISTRY
useful gathering agents; for example, iron hydroxide was used to collect tzaces of germanium ( 9 4 ) ,selenium and tellurium ( I & ? )chromium , (1251,molybdenum (124), and vanadium (47, 186). Lead and bismuth were collected with cadmium sulfide (46); calcium phosphate was used for the coprecipitation of iron and cobalt (118), as well as of a number of other metal ions (117). Of particular interest is the increasing use of organic precipitants in the coprecipitation of trace metals. Lai and Weiss (95) studied the cocrystallization of 27 elements with thionalid and also the use of 2-mercaptobenzimidazole in the collection of 25 diverse elements (160) The use of 8-quinolinol was studied by Weiss and Shipman (161). Organic coprecipitants for the isolation of beryllium and thorium were studied by Sudhalatha (156), and Tappmeyer and Pickett studied various chelating agents for the coprecipitation of selected metals (167). Solvent extraction is being used for an increasing number of applications, and the reviews by Babko and Zharovskii (11) and Zolotov (186) should be consulted. The nature of solvent extraction processes was considered by Alimarin and Zolotov (S),who suggested that coordination-unsaturated chelates are extracted better bv ketoneq, esters, and alcohols than by ethers, hydrocarbons, and halogen-substituted hydrocarbons. Coordination-saturated chelates can be extracted by a great variety of solvents. Selectivity and sensitivity of extraction methods are illustrated by the work of Betteridge and Weqt (dS), who used hexone to isolate the ion-association system formed by the di-n-butylamine complex with silver and stearic acid or , salicylic acid. With this method, only mercury(T1) interferes; the extraction applier over the range of 5 mg. to 5 Mg., and is 97 to 98% complete in a single pass. It should be pointed out that anions, as well as cations, can sometimes be separated by extraction ( 1 7 1 ) . Separation of trace amounts of inorganic ions from aqueous solution by solid-phase distribution is as sensitive as solvent extraction ( f 7 5 ) . Two interesting examples of efficient isolation of specific ions are recorded. Cmon and Sugihara employed a thallous phosphotungstate column for the specific separation of cesium (49). Pierce and Peck isolated mercury from a chloride solution by extraction on a silica gel column impregnated with dithizone (130). Dithiaone was used in a more conventional procedure (93) for determining as little as 0.00005% cadmium in zinc metal. The iodocadmate ion was extracted into a 1% solution of a high molecular weight secondarv amine in xylene, then it was stripped from the organic phase with 1M NstiCO? ;1
conventional dithizone extraction completed the operation. Ilse of gas chromatographic methods for the study of inorganic substances holds promise. Volatile inorganic halides of the transition elementswere separated (90) on columns coated with a eutectic mixture of inorganic halides different from those being separated. Inorganic gases such as carbon monooxide, carbon dioxide, hydrogen chloride, hydrogen cyanide, chlorine, etc. were separated on columns of chlorinated biphenyl, or chlorofluorohydrocarbons on poly(tetrafluoroethy1cne) or poly(chlorotrifluoroethy1ene) with thermal conductivity detectors (140). Phillips and Timms studied volatile hydrides of silicon and germanium and w b stituted borazoles, and discussed active inorganic column materials and conventional column packings (129). Reryllium was volatilized as BeFz and subsequently condensed on a cold finger for spectrographic evaluation (77). ;Imalgam exchange was used for the separation of bismuth (1267, and mercury wm employed as a collector for submicrogram quantities of gold in copper (113). The classic principle of freezing out was recommended by Shapiro for the concentration of dilute solutions (146). Mechanical stirring during freezing is essential. The method is applicable to both organic and aqueous solutions.
QUALITATIVE M E T H O D S
Spot tests and associated techniques represent practically all of the activity in identification methods. This is an area where progress is measured in terms of new reagents or conditioning of reactions with resultant increases in selectivity or specificity. There has been no major advance as such since introduction of the ring-oven technique, although use of ion exchange bends to provide reaction surfaces and scparation media is proving to be a significant contribution. An innovation in technique was suggested by Stewart (163) whereby a few drops of dilute myriqtic acid in light petroleum are added to the dilute test solution. -4unimolecular film is formed which acts as a collector for cations. By manipulation, this is converted to a narrow strip which is then treated with appropriate reagents for individual metal ions that may be concentrated in the film. Reactions used in chemical identification were classified into eight main types by Weisz (164). The classification serves as a guide in the evaluation and elaboration of new methodr. .4 number of new tests were proposed that are of interest. Jungreis and Lerner (89) proposed an indirect test for aluminum; aluminum displaceq calcium
ion from calcium fluoride and the released calcium is then detected by its reaction with glyoxal bis(2-hydroxynnil). The test is remarkably selective and sensitive. Lithium, which is always difficult to detect except by flame methods, can be identified with thoron ( I ) in d k a l ~ n emedium after all interfering ions are remoT~ed with a siisIiension of rnagneiiiim carbonate (149). Goldstein and L i h r g o t t (79) suggested the ui;e of isatin 3-p-nitrophenylhydrazone, which forms a n acid-soluble blue Inke, to test for niagneFiuni. The test, which is very wlective, has a limited identification of 2.5 pg. Sensitivity can be enhanced by the addition of I%i(OH)aas a trace cmollector. Anger (8) also proposed a new test for magnesium that enil)loys the condensation product of glutaconaldehyde and barhituric acid. In the presence of magnesium ion, a blue lake is formed which doe5 not fluoresce, althlxigh the reagent itsvlf fluoresces strongly in alkaline solution. Only magni.sium reacts in alkaline mcdium, and the limit of detection is 0.1 p g . h new reagent and test were proposed for cobalt ( 7 ) , and t n o new tests for vanatliuni (13El 160) were suggested which seem satisfactmy. Pribil and Kolianica (133) found that the reaction between gallium and xylenol orange at very low pH values is sensitive, and in the Iiresence of triethanolamine and ammonium fluoride, only high concentrations of copper interfere among the bi- or trivalent metal ion?, Cadmium, which always presented a challenge, can be detected in the forin of [CdlZr4]-2, which reacts with bis(p-methylbenzylaminoliheny1)antipyrinylmethanol to fovm a blue-violet precipitate in acidic solution. The reagent is quite selective and, under certain conditions, as little as 0.01 pg. of cadmium can be detected (184). .\ specific test for cadmium was prol)osed by K e s t and Diffee (168) who used ion exchange beads to isolate cadmium as its tetr,ziodo complex. The isolated complex Tias then identified on the bead surfaie with glyoxal bis(2-hydroxyanil) . Hydroxanic acids and their use in microscopic identifications of alkaline-earth elements were studied by Gagliardi and Raber ( 7 5 ) . The most exciting developments in the area of wet-chemical methods are associated with the ring-oven technique of Weisz. Krisz modific>dthe technique to include concentration of substances on paper strips (162) and he used the ring oven to open up microgram quantities of difficiiltly soluble samples ( I 63). Various scheme: were proposed for separation of conip:ex niixturcs of ions by the ring oven (180, 121. 147). A system for com1)lfSte qualitative analysis on a single drop, baped on the combination of ring oven, cation exchange paper, and emission spectrog-
raphy, was suggested (115) and a semiquantitative autoradiographic determination of radio isotopes was proposed (165). The ring oven was suggested also for the study of dilute radioactive solutions (103) and, with appropriate spot tests, was applied in the detection of aluminum (104), uranium (106), various elements released from organic compounds ( l o g ) , and in the detection and estimation of antimony (169) and beryllium (173) isolated from airborne particulate samples. The method was also used for the semiquantitative determination of anions which are washed to the ring zone and there converted to difficultly soluble silver salts. Excess silver is removed, the deposited silver salts are converted to silver sulfide. and the resulting stain is compared with standard rings for quantitative evaluation (44).Accessories for use with the ring oven were proposed (170) which permit ring-to-ring separations and purification of filter papers. I n regard to the latt,er, it was pointed out that impurities such as iron and selenium are usually present in sufficient amount to justify or even require purification of filter papers used in quantitative studies in which t>hering oven is employed. QUANTITATIVE METHODS
Quantitative methods have been based mainly on electrochemical or optical methods, which to a large extent are reviewed elsewhere. On the ultramicro scale, A41-Mahdi,Magee, and Wilson examined a number of precipitants for iron and nickel and concluded (6) that potassium ferrocyanide is best suited for iron and dimethylgloxime, for nickel. The microgravimetric determination of copper, zinc, and nickel can be accomplished (68) by [N,X’-di(allylthiocarbanioyl)hydrazine]. A number of titrimetric procedures were proposed based on the use of EDT.4. The titrimetric determination of mercury can be carried out by sodium diethyldithiocarbamate (10). The bulk of the wet-chemical procedures involve spectrophotometric methods. Such methods are now available for practically all ions and evcn fluoride is now yielding slowly (181) and direct methods for its estimation are being deve1ol)ed. The cerium(II1) and alizarin complexone leaves much to be desired, but it does provide a direct color reaction nith fluoride; it is hoped that further progress will be made with this ion in the future. Reaction rate studies and the application of catalyzed reactions prove very useful, particularly for tests that require great sensitivity. The application of catalyzed and induced reactions were reviewed by Bognar (SO), who also investigated the mechanism of such reactions (29) 32). I3ognar and Sarosi applied catalytic methods t o the de-
tection of osmium (34, 56) and in the determination of iodide (53). The ultraniicrodetermination of iodine was also studied by Llalmstadt and Hadjiioannou (105), who used the SandellKolthoff reaction. Optimal conditions for this reaction were studied by Stolc (164), who also studied interference of certain ions (166) with catalytic action of iodine in this reaction. Catalytic methods were proposed for the determination of thiosulfate (31, I l l ) , vanadium (56),and thiocyanates (110). Erdey and Svehla discwssed the determination of trace nietals by chronometric methods (62). Yatsimirskii and Fedorova (181)proposed a new method termed “catalimet~ric’’ titration for determining trace elements. I n principle, this involves titration of an inhibitor with a catalyst solution or vice versa. Measurement of catalytic activity of either the titrated or titrating substance is used to establish the end point. The method is claimed to be sensitive and highly accurate. Two papers dealing with spectrophotometric methods warrant special mention. For trace analysis, at least, automatic methods are rapidly becoming of great interest, and the automatic determination of chloride, nitrate, nitrite, iron, and ammonium in water in the low parts per billion range indicates the possibilities that exist for providing sensitive and precise measurements ( 4 1 ) . Likewise, the work of Dagnall and West (49) on the use of direct spectrophotometry in nonaqueous media is important. With the growing importance of extraction methods for separation, it is highly desirable to have color systems that can be developed in the nonaqueous stage so that final measurements can be made on the extracted material. In the work cited, silver in the range of 0.1 to 10 p.p.m. was extracted from aqueous solution as the di-n-butylamine salicylate into metal isobutyl ketone. Measurement of the silver was made on the hexone extract by direct color development with pyrogallol red. KO anion or cation compatible in solution with silver ion causes interference except mercury(I1) when the extraction is made from aqueous solution masked with the sodium salt of anthranilic acid-diacetic acid. Fluorescence and luminescence are being used in a variety of applications. Patrovsky (127) reviewed the applications of luminescence, and the use of fluorescence analysis in the determination of inorganic impurit,ies was discussed (40). Mock and Illorgan employed the fluorescence intensit’y of aluminum-Pontachronie 13lue-IZlack R to determine iron in the parts per billion range ( 2 7 ) , and Aberti and Saini utilized highly fluorescent zinc phosphate in the presence of uranium for the VOL. 36, N O . 5, APRIL 1964
147 R
direct fluorimetric determination of uranium in aqueous media ( 1 ) . 1 1 though the method is not so sensitive as conventional fluorimetry of fused alkali fluorides, it does have the advantage of simplicity because it applies to aqueous media. Among the optical methods that can be expected to play an ever increasing role in microanalysis is atomic absorption spectrometry. Reviews of this field were published by Robinson ( 1 3 3 , Allan (4, hlilazzo ( f l b ) , L'vov (loo), Poluekt,ov (132)) and Leithe (98). A general discussion of the theory of atomic absorption analysis appeared ( l O f ) , and the physical basis for the method was discussed (?4). Excitation processes and their effect on population distributions and ground state concentrations were considered (78), and critical observations on atomic absorption methods were made by Robinson and Kevan (137, 138). Franswa discussed the t'hcoretical background of this method (68) and described several analytical applications (69). Gatehouse and Willis described a simple atomic absorption spectrophotomet'er and discussed its use (76). The scope of this method can be deduced by noting its application in the determination of molybdenum and strontium (50), lead in urine (178), chroniium in iron and steel (92), magnesium in iron ( I d ) , and iron in tungsten carbide (13), and in t'he estimation of trace met'als in the ocean (64). S o t all metals can be determined by atomic absorption spectrometry, and it is generally assumed that those metals that form refractory oxides do not lend t,hemselves to study. With nen techniques, it is probable that the scope of the method will be extended, however, particularly with advances in methods for atomizing samples. For example, aluminum, which has given difficulty, can be atomized (56) from chelates, and similar techniques may prove to be of value with other metals. The electron probe technique is solving difficult problems. Design and operation of an electron probe microanalyser was discussed by Duncumb ( 5 7 ) , and bhe devclopnierit' of two commercial models was also discussed (6). Heinrich outlined the principles of a scanning electron probe microanalyzer which permits background correction to be made and provides for more accurate detection of concentration differences a t high signal levels (83). Bird (25) described applications of t'he electron probe in the qualitative and quantitative analysis of deposits, surface layers, and metal sections. Seebold and Dirks described (145) the identification of precipitates in diffusion zones through use of the electron probe t,echnique. Elcctroanalytical methods are, of course, widely used in inorganic micro148 R
ANALYTICAL CHEMISTRY
analysis. Typical examples of some of the more important applications are given, and special attention is directed to the coulostatic or charge-step method which shows exciting possibilities. Delahay and Ide introduced this technique (61-65), pointing out its possibilities in determining oxidizable or reducible substances in concentrations in the order of IO-^ to lo-' mole per liter. The method is based on determinations of potential time variations at' open circuit after abrupt change of t'he charge on the hanging drop mercury electrode. .A vacuum tube electrometer csn be used to measure the cell voltage during the decay of capacitor-stored potentials (65). Aramata and Delahay (9) combined the coulostatic method with anodic stripping with a mercury electrode, Such modifications of technique and the development of sophisticated equipment should make this R very versatile method for the analysis of dilute systems. The value of anodic stripping voltammetry was illustrated by the work of DeMars (55) who employed this method for the simultaneous determination of tin and indium in binary alloys. The method was also used in determining silver in metallic uranium (183). Specker, Schiewe, and Trub (151) used this technique in determining copper and lead in hydrochloric and sulphuric acids. Laitinen and Lin (96) used anodic deposition and cathodic stripping of chloride a t silver electrodes for estimating chloride in the microgram range, and a cathodic stripping coulometer was proposed (102) for the quant'it,ative determination of dilute solutions of chloride ion. Small concentrations of chloride ion were also determined by Peters and Lingane (I%?), who equilibrated the sample with solid silver chloride and measurcd the silver ion concentration by potentiometric titration with iodide ion. Monk and Steed (114) described microcoulometric methods for determining several elements based on the generation of EDTA by electrolysis of the mercury chelate. A versatile mercury film electrode for use in chronopotentiometry and microcoulometry was described by Moros ( 1 1 9 ) , and Elving and Smith discussed the use of the graphite indicat,ing electrode (60). The use of nondropping electrodes waq discussed (61). A novel approach to the polarographic determination of alkaline-earth mptals was proposed that is based on the exchangeability of cobalt(I1) with the alkaline-earth metals in their complexes with EDTaI(16.9), After the controlled release CJf the ions, their memurement is made polarographically by drtermining the levels of the Ag+-.kg complex system caused by the introduction of the a1kaline-earth sulfates.
ACKNOWLEDGMENT
The assistance of T. P. Ramachandran, Sham La1 Sachdev, James lliller, G. C. Gaeke, Raul Morales, and C. L. Chakrabarti in checking much of the original literature is gratefully acknowledged. LITERATURE CITED
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(39) Ibzd., Part J1: 1554. Amendment N o . 1 (June 11, 1961). (40) Bozhevol’nov, E. A., Serebryakova, G. B., Yanishevskaya, V. M., Kreingol’d, 8. U.,Acta Chim. Acad. Sci. Hung. 32, 199-206 (1962). (41) Britt. R . D.. Jr.. ANAL. CHEM.34. ‘ f728 (1962). (42) Bush, 31. T., Mzc-ochem. J . 5, 159162 (1961). (43) Caron, H. L., Sugillara, T. T., ANAL. CHEM.34, 1082 (1962). (44) Celau. &I.B.. Weitix. H.. Mzkrochim. ‘ Acta 1662, pp. 24-28. ‘ (45) Cheng, K. L., ASAL. CHEM. 33, 783-790 (1961). (46) Chuiko, V. T . , JIamenko, A. U., Tr. Ternovol’sk. Med. Inst. 1, 202-208 (1960). (47) Chuiko, V. T., Tcldorov, I. A,, Izv. Vysshukh Cchebn. Zzvedenzz Khzm. z Khzm. Technol. 3, 98:3-990 (1960). (48) Claassen, A , , Cham. Weekblad 58, 33-38 (1962). (49) Dagnall, R. SI, West, T. S., Anal. Cham. Acta 27. 9-14 1 1962). (50) David, D.’ J., h.ature 187, 1109 (1960). (51) Delahay, P., ASAL CHEM.34, 1267 (1962). (52) Delahay, P., Anal. Chim. Acta 27, 90-93 (1962). (53) Delahay, P., Ide, Yasushi, ANAL. CHEM.34, 1580 (1962:. (54) Zbid., 35, 1119 (1963). (55) DeMars, R. D., Ibid., 34, 259 (1962). (56) Dowling, F. B., Chakrabarti, C. L., Lyles, G. R., Anal. Chim. Acta 28, 392-394 ( 1963). (57) Duncumb, P., J . Inst. Xetals 90, 154-159 (1962). (58) Dutt, N. K., Ahmctd, A. D., Mikrochim. Acta 1961, pp. ,571-575. (59) Dziomko, V. X , Dunaevskaya, K. A,, Acta Chim. Accid. Sci. Hung. 32 223-227 ( 1962). (60) Elving, P. J., Smith, D. L., U. S Atomic Energy Conim. Repl. TID15,658 (1963). (61) Engelsman, J. J., Chem. Weekblad 58, 113-115 (1962). (62) Erdey, L., Svehla, G., “Analytical Chemistry 1962,” pp. 343-350, Elsevier, Amsterdam, 1963. (63) Erdos, J., Mikroc,‘Lim. .4cta 1961, pp. 515-516. (64) Fabricand, B. P., Sawyer, R. R., bnnar. S. G.. Adler. S.. Geochim. Cos&ochim. Acta 26, 1023-1027 (1962). (65) Faktor, M . M., Carasso, J. I., Chem. Ind. London 1961! pp. 1062-1063. (66) Feigl, F., “Analytical Chemistry 1962,” pp. 12-20, Elsetier, Amsterdam, 1963. (67) Francis, H. J., Mimochem. J . 6, 435457 (1962). (68) FiansG-a, C. E. M., Chem. Weekblad 58, 177-183 (1962). (69) Ibid., 58, 189-195 (1962). (70) Fujimoto, M., Fuks,bori, N., Nakatsukasa. Y.. Anal. Chim. Acta 29. 335-339 (1963). - ~ - , (71) Fujimoto, M., N%katsukasa, Y., Ibid., 27, 283-287 (1962). (72) Ibid., pp. 373-376. (73) Ibid., 26, 427-433 (1962). (74) Fuwa, Keiichiro, Vallee, Bert L., ASAL. CHEM.35, 942 (1963). (75) Gaeliardi. E.. Raber. H.. Monatsh. ‘ Chem.”93, 360-368 (19Si). ’ (76) Gatehouse, B. &I., Willis, J . B., Spectrochzm. Acta 17, 7 10-718 (1960). (77) Geilmann, W., Estebaranx, A. de Alvaro, Z . Anal. Ch(?m. 190, 60-66 (1962). (78) Gibson, J. H., Grosi3man, W. E. L., Cooke, W. D., ANAL. CHEM.35, 266 ( 1963). (79) Goldstein, D., Libergott, E., Mikrocham. Acta 1962, pp. 352-356. ~
~~~
~~
\
(80) Grimaldi, F. S., Helz, A. W., U . S . Geol. Surv. Profess. Papers 424-D, 388-391 11961). (81) Hahn,‘ F. L., Microchem. J . 6, 199210 (1962). (82) Hegedus, A. J., Acta Chim. Acad. Sci. Hung. 30, 21-27 (1962). 183’1 Heinrich. K. F. J.. Rev. Sci. Instr. ‘ 33. 884 (1962). Helbig, W., Chem. Tech. Berlin 13,
Hofstader, R. A , , Microchem. J . 6, 310-326 (19621. (87) Holm-Jensen, I., Scand. J . Clin. Lab. Invest. 12, 247-248 (1960). (88) Hoyle, W., Sanderson, I. P., West, T. S., Anal. Cham. Acta 26, 290-300 119621. (89) Jungreis, E., Lerner, A,, Ibzd., 25, 199-201 (1961). (90) Juvet, R. S.,Wachi, F. M.,V. S. Patent 3,048,029. U. S.A. date appl., (XIarch 19, 1959). (91) Kembler, N . F., Farmer, A,, J . Chromatog. 10, 106-108 (1963). (92) Kinson, K., Hodges, R. J., Belcher, C. B., Anal. Chim. A c f a 29, 134-138 ( 1963). (93) Knapp, J. R., Van Aman, R. E., Kanzelmeyer, J. H., ANAL. CHEM.34, 1374 i1962). (94) Kuus, Kh. Ya., Z h . Analit. Khim. 16, 166-170 (1961). (95) Lai, XI. G., Weiss, H. V., ANAL. CHEW34, 1012 (1962). (96) Laitinen, H . A., Lin, Zui-Feng, Ibid., 35, 1405 (1963). (97) Lassner, E., Chemist-Analyst 51, 14 ( 1962). (98) Leithe, W . , Angew. Chem. 73, 488492 (1961). (99) Lott, Peter F., Cukor, Peter, hloriber, George, Solga, Joseph, A N A L CHEM.35. 1159 (1963). (100) L’vov; B. V., Spectrochim. Acta 17, 761-770 (1961). (101) L’vov, B. V., Zavodsk. Lab. 28, 931-938 (1962). (102) lladdox, W. L., Kelley, 11. T., Dean, J. A , , J . Electroanal. Chem. 4, 96-104 (1962). (103) Sfalissa, i3., Loley, F., Anal. Chim. Acta 27, 381-386 (1962). (104) Malissa, H., Ottendorfer, L. J., Ibid., 25, 461-462 (1961). 1105) Rlalmstadt, H. V., Hadjiioannou. T. P.. ASAL. CHEM.35. 2157 (1963). (106) Xiatic, XI., J . 8.’ Afrzcan Chem. Inst. 14, 100 (1961). (107) Rlaurmeyer, R., Mzcrochem. J . 5, 341-359 (1961). (108) Ibzd., 6, 459-477 (1962). (109) Meisel, T., Semeth, A., Erdey, L.. Mzkrochzm. Acta 1961. DD. 874-879. (1lOj Slichalski, E., Wto;&dwska, A., Chem. Anal. Warsaw 6, 365-375 (1961). (111) Ibzd., 7, 783-790 (1962). (112) ;IIilazzo, G., Chim. Ind. Jlilan 44, 493-500 ( 1962). (113) Mizuike, A., Talanta 9, 948-953 (19621. (114) -3lonk, R. G., Steed, K. C., Anal. Chim. Acta 26, 305-315 (1962). (115) Mooney, J. R., ASAL. CHEM.34, 1506-1507 -( 1962). (116) Alorachevskii, Yu. V.. Vol’f, L. A , . ‘ Zh. Analit. Khim. 15, 656-660’(1960): (117) Morachevskii, Yu. V., Zaitsev, V. S . , C‘ch. Zap. Leningrad. Gos. I-niv. 1960, pp. 90-95. (118) Alorachevskii, Yu. V., Zaitsev, V. N., Taranov, A. P., Ibid., pp. 85-89. (119) SIoros, S. A., A N A L . CHEM.34, 1584 (1962). (120) Alunshi, Kailash Nath, Dey, Arun K., Nikrochim. Acta 1962, pp. 874-877. (121) hlusil, A , , Haas, W., Drabner, J., Ibid., pp. 1121-1123.
(122) Neeb, R., Angew. Chem. Intern. Ed. Engl. 1, 196-206 (1962). (123) Noebels, H. J., Ann. N . Y . Acad. Sci. 87, 934-943 (1960). (124) Novikov, A. I., Zh. Analit. Khim. 16, 588-591 (1961). (125) Ibzd., 17, 1076-1081 (1962). (126) Orbe, F. E., Qureshi, I. H., Meinke, W. W., ANAL.CHEM.35, 1436 (1963). (127) Patrovsky, V., Chem. Listy 56, 795803 (1962). (128) Peters, D. G., Lingane, J. J., Anal. Chzm. -4cta 26, 75-80 (1962). (129) Phillips, C. S. G., Timms, P. L., ANAL.CHEM.35.505 (1963). (130) Pierce, T. B., Peck, P. F., Anal. Chim., Acta 26, 557-567 (1962). (131) Pollard, F. II., Nickless, G., Burton, K. W. C..J.Chromatoa. 8,507-509 (1962). 1132) Poluektov, N. S:. Zavodsk. Lab. 27. ’ 830-836 (1961). (133) Pribil, R., Kopanica, XI., Mikrochim. Acta 1962, pp. 29-31. (134) Pribil, R., Vesely, V., Talanta 8, 880-884 (1961). (135) Rao, V. Pandu Ranga, Satyanarayana, D., Ibid., pp. 846-848. (136) Robinson, J . W., ANAL.CHEY.33, 1067-1071 (1961). (137) Robinson, J. W., Anal. Chim. Acta 27, 465-469 (1962). (138) Robinson, J . W., Kevan, L. J., Ibid.. 28. 170-175 11963). (139) Roo;, J. B., Analyst 87, 832-833 (1962) \ - - - - I .
(140) Runge, H., 2. Anal. Chem. 189, 111-124 (1962). (141) Sawyer, P. O., Flaschka, H., “Analvtical Chemistrv 1962.” DD.825828 Efsevier, Amsterdam, 1963: (142) Schulek, E., Remport-Horvath, Zs., Laszlovsky, J., Mikrochim. Acta 1962, pp. 64-70. (143) Schulek, E., Remport-Horvath, Zs., Lasztity, A,, Talanta 9, 529-530 (1962). (144) Ibid.. 10. 821 (1963). (145) Seebold,’R. E:, Birks, L. S., ASAL. CHEM.34, 112 (1962). (146) Shapiro, J., Science 133, 2063-2064 (1961). (147) Singh, Eric John, Dey, Arun K., Mikrochim. Acta 1961, pp. 366-369. (148) Skdos, G . P., Ibzd., 1962, pp. 32-36. (149) Soboleva, T. A., Suslov, A. P., Davletshin, .4. A , , Tr. C‘ral’sk. Polztekhn. Inst. 105, 67-70 (1962). (150) Sommer. L.. 2. Anal. Chem. 185. ‘ 263-266 f 19k2).‘ (151) Specker, H., Schiewe, G., Trub, H., Ibid., 190, 144-148 (1962). (152) Stephen, W. I., I n d . Chemzst 37, 499-501 (1961). (153) Stewart. F. H. C.. Chem. Ind. London 1961, 1064-1065. ’ (154) Stolc, V., Mikrochim. Acta 1961, pp. 710-720. (155) Stolc, V., 2. Anal. Chem. 183, 262267 (1961). (156) Sudhalatha, K., Talanta 10, 934 (1963). (157) Tappmeyer, W. P., Pickett, E. E., ANAL.CHEM.34, 1709 (1962). (158) Tarayan, V. AI., Arstamyan, Zh. Xf., Izv. Akad. Nauk A r m S S R , Khim. Nauki 15, 329-336 (1962). (159) Tockstein, .4,,Novak, V., Mikrochim. Acta 1962, pp. 142-154. (160) Weiss, H. V., Lai, 11. G . , Anal. Chim. Acta 28, 242-248 (1963). (161) Weiss, H. V., Shipman, W . H., A N A L CHEM.34, 1010 (1962). (162) Weisz, H., Jlikrochin. Acta 1962, pp. 830-834. (163) Ibid., pp. 922-925. (164) Weisz, H., 2. Anal. Chem. 191, 94104 (1962). (16:) Weisz, H., Klockow, D., Anal. Chim. ilcta 28, 467-4i1 (1963). (166) West, P. W.,Acta Chim. Acad. Sci. Hung. 34, 143-149 (1962). ’
VOL. 3 6 , NO. 5 , APRIL 1964
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(167) West, P. W., AXAL. CHEM. 34, 104R-lllR (1962). (168) West, P. W., Diffee, J., Anal. Chim. Acta 25, 399402 (1961). (169) West, P. W., Llacer, A. J., ANAL. CHEM.34, 555 (1962). (170) West, P. W., Llacer, A. J., Cimerman, C., Mikrocham. Acta 1962, pp. 1165-1168. (171) West, P. W., Lorica, A. S., Anal. Chim. Acta 25, 28-33 (1961). (172) West, P. UT., lIarDonald, A. hf. G., West, T. S., “Analytical Chemistry 1962,” Elsevier, Amsterdam, 1968. (173) West, P . W., llohilner, P. R., AXAL.CAEM.34, 558 (1962).
1174) West. P. W.. Ordoveza. Fe. Ibid., ‘ p.’1324. ’ 1175) West. T. S.. Anal. Chim. Acta 25. 405-421 (1961).‘ (176) West, T. S., Analyst 87, 630-636 ( 1962). (177) West, T. S., Ind. Chemzst 38, 35-37 81-83 (1962). (178) Willis, J. B., ‘Vatwe 191, 381-382 (1961). (179) Yamaguchi, Koichi, Ueno, Keihei, Talanta 10, 1041 (1963). (180) Ibid., p. 1195. (181) Yamamura, S. S., Wade, >I. A., Sikes, J. H., ANAL.CHEM.34, 1308 ( 1962). (182) Yatsimirskii, K. B., Fedorova, T. I
,
I., Dokl. Akad. Nauk SSSR
143, 143145 (1962). (183) Yoshimori, Takayoshi, Yamade, Tsugihiko, Hongo, Tsutomu, Takeuchi, Tsugio, J . Chem. SOC. Jawnn, Ind. Chem. S e c t . 65, 1808-1811 (1962). (184) Zhivopist?ev, V. P., Chelnokova, 3T. N., 1:ch. Zap. Permsk. Cos. Univ. 19, 87-91 (1961). (185) Zolotavin, V. L., Korznyakova, E. G., T r . Ural’sk. Politekhn. Inst. 121, 9-17 (1962): (186) Zolotov, Yu. A., Zavodsk. Lab. 28, 1404-1408 (1962).
This work Rupported in part by Public Health Service Research Grant A P 00117 from the Division of Air Pollution, Bureau of State Services.
Organic Microchemistry T. S. Ma and Milton Gutterson, Department o f Chemistry, Brooklyn College, City University o f New York, Brooklyn
T
H I S REVIEW, like the previous ones on organic microchemistry, covers only elemental analysis and the determination of organic functional groups and rovers the period from October 1961 to September 1963. l y e mentioned in our last review (255)that the current trend in microchemistry is concerned with the principles and methods of chemical esperimentation using the minimum quantity of working material t o get the maximum amount of chemical information. This trend is particularly significant in the developments in quantitative organic microanalysis during the past two years. Thus, considerable effort has been devoted to the determination of carbon, hydrogen, nitrogen, and other elements in less than 1 mg. of organic material. Simultaneous determination of several elements with one sample-w hich conserves the working material and usually also time-is the theme of many research papers. Since gas chromatography is a tool especially suited for separations on the milligram to microgram range, it is not surprising to find that the organic microchemists are utilizing this technique to perform quantitative analysis of progressively smaller quantities of materials. The applications of gas chromatography to organic elemental analysis are amply documented in the succeeding sections. *\ beginning has also been made to use gas chromatography in microdeterminations of organic functional group’, wch a$ the alkosyl (gal), amino (1.54), alkimino, carbo\j 1, and C-methyl (266) groups. 1Iore actirities in this field are to be elpect ed. dutomation has come to the organic microanalytical laboratory. X number
150 R *
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of publications have appeared which describe the assemblies for automatic determination of carbon, hydrogen, nitrogen, and sulfur. Several manufacturers (65, 93, 102, 411) have put out commercial models of automatic analyzers. It should be noted that the chief advantage of the automatic apparatus is saving of labor. These machines are recommended for routine analytical work where many samples have to be processed during a short period of time. They are not intended to produce better results than the conv6ntional manuallyoperated assemblies. ELEMENTAL ANALYSIS
Carbon and Hydrogen. Rapid combustions procedures continue t o receive much interest. Pfab (327, 328) pyrolyzed the sample in a slow stream of nitrogen, the products being combusted in a fast stream of osygen a t a jet. h misture of copper oside and silver pumice in the combustion tube ensured complete osidations. Chang, Huang, and Chang (58) employed a combination of preliminary pyrolytic oxidation and catalytic combustion using silver permanganate as catalvst. Oda and co-workers (304, 306) described an apparatus containing a preheated double combustion tube. The sample, placed in the inner tube, is combusted almost instantaneously a t 800°-850” C.; complete osidation is obtained by passing the gaseous products over copper oside with a current of osygen. Imaeda and co-workers (179) combusted the sample in a current of air a t 750°-800” C. Porous copper oside was used as osidant while porous silver was an escellent absorbent for halogens and oxides of
IO, N .
Y.
sulfur. U t s u i , Yoshikawa, and Furiiki 1282) employed combustion with a stream of nitrogen mised with electroIvticallv generated osygen. Meyer and Vetter (27.9) used Co304 as catalyst and precipitated MnOz to remove nitrogen osides in a procedure employing combustion with dry osygen a t 6.50” C. Klimova and Antipova (214) inserted a flash heater of relatively large size in front of the combustion train ensuring complete decomposition of the sample within 2 to 3 minutes. Ingram (173) used closed flask combustions. The flask was modified to contain a quartz chamber. The sample was drawn into the chamber with a magnet and ignition was with osygen which uas passed through the apparatus during combust ion. The development of these rapid techniques inevitably lead to attempts to automate the entire procedure. Maker (263) described a commerciallyavailable unit in which the combustion tubes are vertically mounted and include motor-driven furnaces. Malissa and Pel1 (261) used a packed combustion tube although their studies indicate that empty tube combustion is feasible. Electrolvtic cells automatically record the conductance of an absorbing solution at constant gas pressure for the quantitative measurement of carbon, hydrogen, and sulfur. The results of the determination of these elements simultaneously by their apparatus are encouraging. Gustin (135) combusted the sample in a slow stream of osygen, surrounding the organic compoiind by copper oside which eliminated sample explosions. The procedure is similar to Dumas nitrogen techniques. The final sweep with oxygen is rapid. The time for a deter-
