Review of Fundamental Developments in Analysis
UItraviolet Spectrophotometry Robert C. Hirt
American Cyanamid Co., Stamford, Conn.
T
biennial review of fundamental developments in analysis by ultraviolet spectrophotometry is concerned with the period from the last review (62) until October 1959. It is intended to be selective rather than comprehensive and, therefore, many worthwhile papers on analytical ultraviolet spectrophotometry may not have been mentioned. As in previous reviews, spectra published in connection with spectrastructure correlations, characterization of compounds, and kinetics of reactions have not been included, except for a few cases where the tabulations of band absorptivities appear to be useful in analytical applications. Preference has frankly been given to articles in the English language n hich are readily available to the average analyst. The quality and quantity of papers on ultraviolet spectrophotometry continued a t the high levels of previous years. I n this connection, Bryan (17) presented an interesting survey of publication trends in spectroscopic literature, based upon a n analysis of the bibliography supplied over the past 10 years by the Technical Information Library of the Bell Telephone Laboratory [appearing in Applied Spectroscopy (68)1. Ultraviolet and visible a b s o r p tion are not differentiated, but together account for 2574 of the indexed material. One quarter of this material appeared in ANALYTICAL CHEMISTRY, with another quarter appearing in fohr journals of the -4merican Chemical Society and the American Institute of Physics. The distribution of references in this review differs from that of Bryan’s study, as here the emphasis is placed on articles which are analytical and concerned n i t h the region below 4000 A. There appears to be increasing publication of analytical ultraviolet spectrophotometric articles in Applied Spectroscopy, The Analyst, Analytica Chimica Acta, and Spectrochimica Acta. The recent founding of Talanta and the Journal of Molecular Spectroscopy should also be noted as sources of articles concerned with ultraviolet spectrophotometry. HIS
BOOKS
New editions of two important books have appeared. Lothian (86) has rewritten the 1949 edition, bringing it up
to date. As in the earlier edition, there are three sections on principles, applications, and technique, with a section on further reading and a bibliography. It has been reviewed (98, 104). Gillam and Stern (44) have revised their 1954 book and have added more material. It also has been reviewed (113). These two books tend to complement each other, although the basic material must necessarily be present in both. Books on general analytical methods and on instrumental analysis generally devote a chapter to ultraviolet spectrophotometry, although sometimes it appears jointly with colorimetry. These treatments universally suffer from their brevity, and can often do little more than give a taste of the subject along with directions for finding more material in the literature. A third edition of Willard, Slerritt, and Dean (149) devotes 42 pages to ultraviolet and visible spectrophotometry with illustrations and diagrams of modern instrumentation. Haslam (67) has reviewed this text from a British point of view. Delahay (SO) likewise has assigned a similar amount of space to absorption spectrometry and filter photometry. Part of a chapter (about 14 pages) in Fritz and Hammond (41) is devoted to ultraviolet methods. Other chapters in books on analytical chemistry include those by Jones (69) [reviewed ( 6 6 ) ] and by Meites and Thomas (93) [reviewed (146)l. The importance of singlet-triplet absorption bands and their origin are discussed in a book on excited states by Reid (108) and in a review by the same author (109). The proceedings of the Conference on Molecular Spectroscopy of the Petroleum Hydrocarbon Research Group have been published in book form, edited by Thornton and Thompson (158).
Chapters primarily concerned with colorimetric methods contain much material pertinent t o ultraviolet spectrophotometric methods, such as the chapter by Mellon (94) in “Trace Analysis,” edited by Yoe and Koch (160). Boltz (14) also includes ultraviolet methods for some nonmetals. Glasser has written a chapter (46) in a handbook concerned with continuous methods of analysis (27). His previous work (46) constitutes part of
another book on continuous analytical methods by Siggia (126). Many ultraviolet methods for elemental analyses are included in the new edition by Snell, Snell, and Snell (123)) covering work up to January 1956. Ultraviolet methods are not differentiated from visible methods. NOMENCLATURE AND METHODS
The nomenclature situation-definition of terms, symbols, and usage, as in the plotting of spectra in publicationsappears t o have improved steadily over the recent years. There appears to have been considerable cooperation among the editors of the various journals and their reviewers in an attempt to achieve some degree of uniformity. The absorbance-absorptivity terminology has become widespread. The Nomenclature Subcommittee of American Society for Testing iMaterials Committee E-13 on Absorption Spectroscopy has published (114) a list of 20 terms and definitions which were agreed upon by that committee’s membership after considerable discussion and study. A supplementary list of terms and definitions has been proposed (116). The Subcommittee on Apparatus Specifications of ASTM E-13, under the chairmanship of T. R. Harkins, prepared for publication, for information only, the “Proposed Methods for Evaluation of Spectrophotometers” (116); this is a t present being subjected to round-robin testing in several laboratories. The Subcommittee on Methods of ASTM E-13 has prepared, under the chairmanship of R. T. O’Connor, three publications as information only; these are, a “Proposed Format for ASTM hlethods Involving Absorption Spectroscopy,” “General Technique of Infrared Quantitative Analysis,” and “General Technique of Ultraviolet Quantitative Analysis” (f 16). COLLECTIONS OF SPECTRA
Project 44 of the American Petroleum Institute has continued to issue ultraviolet spectra periodically ( 2 ) . Including the supplementary issue of April 30, 1959, these spectra now number 806. Recently, the Sadtler Research LaboraVOL 32, NO. 5, APRIL 1960
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tories (118) announced the start of publication of reference ultraviolet spectra, with the first 1000 curves due in September 1959. These spectra are run on a Perkin-Elmer Warren Spectracord, and are reproduced on sheets 8l/2 X 11 inches for loose-leaf notebook filing. IBM PUNCHED CARDS
The Subcommittee on Standard Data of ASTM E-13 has continued the coding of ultraviolet spectral d a t a from t h e literature. T h e deck available now numbers 10,900 cards. Name-formula index cards for these spectra have been prepared. The book of directions for both infrared and ultraviolet spectral d a t a cards has been revised (76). 9 chapter entitled “Punched Cards as Aids to Qualitative Chemical Analysis by Spectral Methods” was written b y Kuentzel (77),appearing in a book on punched cards by Casey et aZ. (19). INSTRUMENTS, CEUS, AND ACCESSORIES
The principles of several instruments, including typical present-day ultraviolet spectrophotometers, were discussed by Lewin (81) . Detailed performance tests on the Beckman DK spectrophotometers were described by Cahn and Henderson (18); these, together with the ASTM tests (115), give the user some practical tests to try, Three new spectrophotometers of varying complexity, produced in Europe, were described (87). A simple, nondispersive ultraviolet photometer has been built, using a fluoresccnt black light as a source (136); this is the ultraviolet analog of a filter photometer and should prove useful. Spectrophotometry in the 194- to 225-mp range is proposed ( 6 6 ) ; the use of a solar-blind phototube solves many of the stray light problems usually encountered with single monochromators in this range. The behavior of lead sulfide photocells in the ultraviolet is reported (127). Adaptstion of Beckman and Cary spectrophotometers for low and high temperature n-ork has been described (54,61). The very high temperature of 780” C. \vas used in studying spectra in molten fluoride salts with a Carp Model 14 (1.51). Electrically heated glass ampoules in the beam of the instrument were used for solutions above their boiling points (48). A cell for optical measurements a t very high pressure has been described (36). Several modifications of the Unicam SP.500 instrument have been devised. A method similar to the adaptation of the Beckman D U was employed by Shrewsbury (124), a n alternating path with rotating mirror and single detector was used (63),an optical comb attentuator and a n alternating-positioned I
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mirror was another device (GO), and the conversion was described in detail with before-and-after performance tests included (73). Interest in the measurement of ultraviolet reflectance, a somewhat neglected field of study, was shown by the introduction of reflectance attachments for the Beckman DK-1 and DK-2 (71) and the Perkin-Elmer M7arren Spectracord (3). A means of measuring reflection interference spectra of thin films has been outlined (84). The diffuse reflectance of powdered inorganic salts diluted with lithium fluoride was studied with a Unicam SP.500 n-ith a reflectance attachment (49). Microspectrophotometry of very small samples was done with a combination of xenon lamp, grating monochromator, and quartz microscope (133), and with a prism monochromator and reflection microscope optics (60); spectra of objects as small as 1 micron were obtained. A double monochromator system for microspectrophotometry was described by Stahl (131). Systems for circulating solutions being titrated continue to be devised, generally simpler than those being built a few pears ago. The centrifugal action of stirring was used to circulate the solution being titrated through short tubes to the absorption cell (Im, 135). An apparatus for titrating submilligram samples used small volumes and capillary burets (13). A means of moving the cell to various positions in the light beam of a Beckman DU in connection with diffusion studies was described ( 7 ); the authors discuss the corrections to absorbance readings which are needed with finite slit widths and nonuniform absorbing systems (8). For use with corrosive liquids such as hydrofluoric and fuming nitric acids, a sapphire-windowed cell was constructed (106). Nonclogging glass pens, interchangeable for different colors of ink, are proposed for use with Beckman DK-2 instruments (6). Some practical directions for the ware length calibration of spectrophotometers with a mercury lamp are given (144) ; dangers of mistaking lines on instruments badly out of adjustment er employing analysts not experienced in spectroscopy are st ressed. VACUUM ULTRAVIOLET
Principal interests in the region below 2000 A. in the past two years appear to have been in instrumentation, rather than in analytical applications of absorption bands. This is probably affected in part by the interest in the emission spectrochemical analysis applications in the vacuum region and the interest in upper atmosphere studies, such as rocket spectroscopy (39). An Ebert grating spectrometer of f/10
and 72-inch focal length has been constructed (35). A grating spectrophotometer was specially designed for use with small solid specimens, featuring a system of easy introduction and manipulation of samples (24). A method of double-beam spectrophotometry is used with sources of unsteady output (67). Commercially available (Jarreli-Ash) spectrometers of the Seya-Namioka type (99, 123) should stimulate studies in the vacuum ultraviolet region. Construction of a 1-meter normal incidence spectrometer has been reported ( I l a ) . Two papers (4, 92) were concerned with wave length standards of germanium lines. The emission spectrum of carbon monoxide may be used for wave length calibration (96). Garton (43) constructed a Lyman-continuum flash source of large aperture. Optical properties, particularly reflection, were the subjects of papers on zinc sulfide (88),magnesium fluoride (58), and thin nietallic films (145). Ionization potentials of molecules from methane to naphthalene were determined (105, 138). The spectra of acetylene and acetylene-& were studied (148). SPECTROPHOTOMETRIC TITRATIONS
Measuring absorbance a t one or more wave lengths in the ultraviolet as a function of p H or volume of titrating solution is increasing in use for determining ionization constants and for quantitative analysis. Headridge (59) has reviewed photometric titrations in general (visible and ultraviolet), including apparatus. Several cells for titrations have been described (IS,107, 135). The extension of the spectrophotometric titration technique to nonaqueous systems was done for a series of phenol derivatives titrated in butylamine (89). An unusual application of this technique involves the determination of water in acetic acid using excess acetic anhydride (16). Ionization constants and spectra of the hydrolysis products of melamine and their ions were presented (68). ELEMENTAL ANALYSIS
Quantitative spectrophotometric methods for the determination of elements are generally based upon the formation of a reaction product or complex which absorbs ultraviolet light. Mellon and Bly (95) have published a “Bibliography of Spectrophotometric Methods for Analysis of Inorganic Ions,” covering ANALYTICAL CHEMISTRY, The Analyst,and Analytica Chimica Acta for 1952-58. Many of the methods referenced involve absorbance measurements in the ultraviolet. In addition, Volume 11-4 of “Colorimetric Methods of Analysis” (129) has been published; this also contains many ultraviolet methods. With the coverage provided
by these two publications, this section of the biennial review need not list or mention many articles of interest. The technique of using a line source instead of a continuum for spectrophotometry when the determination must be done on a slope of the absorption curve was used in the determination of lithium carbide (43). The acetylene evolved in water by lithium carbide in lithium metal was determinrd as the silveracetylene complex. The use of two mercury lines eliminated wave length dial setting errors. Several different analytical reagents were studied for the determination of palladium (9, 90, 121, 242, 143). Spectrophotometry served as a means of studying copper chelates (21, 22). Extraction with isoamyl alcohol and pH adjustment obtained a sensitivity of 0.5 p.p.m. for cobalt with isonitrodimedon (14 1 ) . Colorimetric methods for platinum from 1953-57 were reviewed (11). Total nitrate was estimated by absorbance a t 210 mp for examination of waters and sewage effluents (65). Carbonyl oxygen was determined indirectly by condensing with 2,4dinitrophenylhydrazine and measuring a t 340 mp (85). ORGANIC ANALYSIS
Karr (70) has published a list of the longest wave length bands in the ultraviolet or visible absorption spectra of polycyclic hydrocarbons. Included in this list of 408 compounds are the name, structural formula, longest wave length band, one or more other bands, solvent, and reference. This compilation should be of considerable use to investigators in such fields as coal tar, petroleum, shale oil, air pollution, and cancer research. There are 143 references. Lindsey (82, 83) gives the order of elution by cyclohexane from alumina, analytical wave lengths, and absorbance values for 1-p.p.m. concentration for a number of polycyclic aromatic hydrocarbons. Chromatographic separation followed by spectrophotometry was used for determination of aromatic hydrocarbons in polluted air (137). *4 modified method for polycyclic hydrocarbons was proposed by Commins (26). Mass spectrometry and ultraviolet spectrophotometry were combined to examine the products of distillation and elution chromatography from heavily cracked gas oi1 fractions (47). The ultraviolet absorption spectra of residues from asphaltic materials were presented (119). Total pyridines and quinolines in coaltar distillates were estimated by use of average absorptivities (20). I n the fields of resins, polymers, and coatings, Morath and Woods (97) review methods for analysis of textile resins of the amino formaldehyde type; ultraviolet methods are cited for mel-
amine and thiourea. Swarm and Adams (134) determine salicylanilide in fungusresistant varnishes, using spectrophotometry following an alkaline extraction. Differences in absorbance a t 282.5 and 300 mp are used to determine ptertbutylbenzoic acid in coconut oil-modified alkyds (160). Phthalic acid and anhydride determinations are described in systems involving naphthoquinones (34, 10.2). Determination of methylvinylpyridine in a copolymer of acrylonitrile was described (130). Direct determination of polystyrene in a copolymer was done in chloroform solution (139). The simultaneous determination of ethyl methyl ketone and ethyl acetate in a solvent base for liquid rubber made use of the weak ketone band and short wave length absorption, not a band maximum (38)*
In the determination of alkylaryl sulfonates, use of the 224mp rather than the 270-mw band gave better sensitivity and avoided variations with pH (72). The total concentration of three isomers of toluenesulfonic acids in sulfuric acid was determined by use of mean absorptivity a t 220 mp (103). Useful for identification and analysis are tables of maxima wave lengths and molar absorptivities of a- and P-monosubstituted derivatives of thiophene ( 6 ) . hfonoand dinitrothiophene may be determined in nitrobenzene (80). Parathion and p-nitrophenol mixtures are analyzed by spectrophotometric examination before and after hydrolysis (64). Tables of data as well as interpretative material were presented on the spectra of thionylamines (79). Complexing agents in a polynitroaromatic molecular compound are discussed (74). Coupling with p-diazobenzene sulfonic acid makes feasible the determination of nitroethane, nitropropane, and nitromethane (25)* Two papers were concerned with assay of sulfhydryl groups using Nethylmaleimide (1.111). Reaction with pyridine permitted the determination of chloral hydrate, trichloroacetic acid, and trichloroethanol (40). Mixtures of terephthaloyl and isophthaloyl chlorides may be analyzed in iso-octane solution by use of simultaneous equations (16). The strong absorption of diazonium compounds in aqueous solutions made possible spectrophotometric analyses down to 1 p.p.m. (117). Curves and tables of spectra of methylbiphenyls (12) should be useful for qualitative and quantitative use. For simplicity and rapidity of analysis of large numbers of samples, it was shown that benzoic acid in soft drinks could be assayed by dilution with water, filtering, and measuring a t 230 mp (33). With regard to systems of great complexity, applications of paper chromatography and instrumental anal-
ysis methods in the quality control of pharmaceuticals have been reviewed (101). The ultramicrodetermination of derivatives of tryptophan and kynurenine was discussed, with remarks on the effect of ultraviolet irradiation on some of these compounds (52). Pyridine-2aldoxime methiodide and its stereoisomer were determined (31). hlephensin and its metabolite were subjected to extraction procedures and concentration prior to spectrophotometric examination in order to work in the range of 20 to 100 p.p.m. (88). Komograms for use in the assay of vitamin A and corrections needed for nonlinear background adsorption were presented (100). Nioviobiocin and its dehydro deriva,tive were determined by the two-component analysis method (129). An improved method for nicotine in tobacco smoke was proposed (78). Characteristics of the spectra of various sugars and uronic acids were presented for analytical use (10). Three articles (23, 37, 128) described methods for ketosteroids, using various reactions and spectral shifts from the parent compound. The determination of ~(4-chloro-2methy1phengloxy)propionic acid in commercial grade acid was effected by chromatographic separation of active acid fo!lowed by spectrophotometry a t 287 mp (51). Small samples and rapid microdetermination of hippuric acid in urine were reported (32). Tyrosine groups in proteins and amino acids were studied (147). MISCELLANEOUS
Ultraviolet spectra used as criteria for monoaromaticity are the subject of a n interesting article by Stevenson and McConnell (132). Ultraviolet spectra have been interpreted as showing different modes of solubilization concerned with micelles (110). The role of the various instrumental techniques in microchemical analysis was reviewed by Kuck ( 7 a . Pressure effects in gases on band shifts were discussed (1.49). A mathematical examination of the precision, errors, and cell correction of differential methods was presented (29). Use of spectrophotometry to measure solubilities was made for some amine tetraphenylboron compounds (66). False readings caused by fluorescence of samples were cited as an artifact to be avoided (91). Tunnicliff (140) discussed effects of solvent absorption and gave purification procedure. A comparison between absorption and reflectance spectra of 2,4dinitrophenylhydrazones of acetone and 4methyl-2pentanone showed a shift to longer wave length in going to reflectance (162). Use of picrates and styphanates to determine molecular weights is proposed ( I 25). VOL. 32, NO. 5, APRIL 1960
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LITERATURE CITED
Fritz, J. S , Hammond, G. S., “Quantitative Organic Analysis,” e,sp. Chap. 10, pp. 168-82, Kiley, hew York, 1957. (42) Garton. W. R. S.. J . Sci. Insrr. 36. 11 (1959): (43). Gilbert, T. T.,Jr., Lleyer, .4.S., Jr., \T hite, J. C., A N A L . CHEM.29, 1627 (41)
(1) .4lexander, N. &I., ASAL. CHEM.30, 1292 (1958). ( 2 ) Am. Petroleum Institute, Carnegie Institute of Technology, Pittsburgh, Pa., Project 44. (3) Anacrron, R. E., Koble, R. H., tall: at meeting of SOC.for .4pplied Spectroscopy, New York, Kovember 1958; A p p l . Spectroscopy, in press. (4) Andrew, K. L., Meissner, K. K., J . Opt. S o t . Am. 48, 31 (1958). (5) Andrisano, R., Pappalardo, G., Spectrochim. Acta 12, 350 (1958) (6) Afcus, A . C., ASAL. CHESI.30, 159 (19a8). 17) Back, E., Felicetta, V. F., NcCarthy, J. L.. Ibid.. 29. 1903 f 1F)R7I. (8) Ibid., 301 18?5 (1958j.- ’ 19) Banks, C. V., Smith, R. V., A n a l . Chim. Acta 21,308 (1959). (10) Bath, I. H., Analyst 83,451 (1958). (11) Beamish. F. E.. XcBride. IT. A. E..
(1957)
sorption Data,” 2nd ed.. Am. Soc. Testing Materials, Philadelphia, Pa., September 1958. (77) Kuentzel, L. E., “Punched Cards as Aids to Qualitative Chemical Analysis by Spectral Methods,” Part 11, Chap. 9, 175-232, R. S.. Casey et al , ’kmched Cards: Their Applications to Science and Industry,” Reinhold, Kew York, 1958. (78) Laurene, A. H., Harrell, T. G., ANAL.CHEM.30, 1800 (1958). (79) Leandri, G., Mangini, A., Spectrochim. Acta 12, 421 (1959). (80) Leibmann, W., Koods, J. T , . ~ N A L . CHEM.29,1845 (1957). (81) Lenin, S. Z., Ibid., 30, S o . 6-19.4, NO. 7-17.4 (1958). (82) >ind!ey, A. J., Anal. Chim.-4cta 20, 173 (1939). (83) Ibid., 21, 101 (1959). (84) Lloyd, D. G., J . Sci. Instr. 35, 169 (1958). (85) Lohman, F. H., ANAL.CHEM.3 0 , 9 7 3
(iij-Cjliarn, A . E., Stern, E. s., “Introduction to Electronic Absorption Spectroscopy in Organic Chemistry,” 2nd pd., E. Arnold, London, 1988. (45) Glasser, L. G., J . Opt. S o t . Am. 45, 556 (1955). (46) Glasser, L. G., “Ultraviolet Absorption Method of Analysis,” Section 6-46 of “Process Inetruments and Controls Handbook,” D. RI. Considine, ed., hlcGraa-Hi!l, Kew York, 1957. (47) Gordon, R. J., Moore, R. J., Muller, c. E., ANAL.CHEM. 30, 1221 (1958). (48) Grant, D. W., Glanville, D. E., Strachan. G. L.. Smctrochim. ~ c t a 12,109 (1958). (1958). (49) Griffithr: (12) Beaven, G. H., Johnson, E. A., .~ ~~~.~ -;, T. R., Lott, K. A. (86) Lothian, G. F., “hbsorption SpectroSpectrochim. Acta 14, 78 (1958). photometry,” 2nd ed., hlacmillan, ICew S Ymons, hl. C. R., - 4 h . a ~ . CHESI. (13) Boaz, H. E., Forbes, J. K., ANAL. 1338 ( 11959). York, 1958. CHEM.30,456 (1958). ‘ J . JTt. Sinai Hosp. N (50) Gueft.. B.. (87) Luwher, E., A p p l . Spectroscopy 12, ..- .- .- -. 114) Boltz. D. F.. “Colorimetric Deter24, No. 6, 920 (1957). 172 (19583. mination of gonmeta~s,” VOL WI (51) Haddock, L. A . , Phillips, L. (88) hlaass,’A. R., Carey, P. L., Heming, Anniqst 84. 94 f 1959). of “Chemical Analysis,” Interscience, A. E., ANAL. CHEM.31, 1331 (1959). Sew Tork, 1958. ( 5 2 ) Hak im,’A. A.,Anal. Chim.Acta (89) hlcKinney, R. W.,Reynolds, C. A., 170 (15159). (15) Breda, E. J., ASAL. CHEJI.30, 2020 Talanla 1,46 (1958). ,,nro\ ( IYdOJ. (53) Half?s, J. L., J . Sci. Instr. 35, (90) lIajumdar, A . K., Chakrabartty, I ’ S., Ibid., 31, 1757 (1958). bl. )I.. A n a l . Chim. Acta 20. 379 ( .16) Bruckenstein, i 1959). (54) Halperin, A., Braner, A., Rets. Sn’. ( 19591. Instr. 78,959 (1957) (17) BGan, F. R., A p p l . Spectroscopy 12, (91) hlehler, A . H., Bloom, B., Ahrendt, (55) Hansen, R. E., Buell, M. V., ANAL. 133 (19%). RI. E., Stetten, D. \V.,Jr., Science 126, CHEK 31,878 (1959). (1s) Cahn, L., Henderson, B..D. J . Opt. 1285 (1957). ( 5 6 ) Haslam, J., Anolysi 84,326 (1959). S’oc. Am. 48,380 (1958). (92) Ileissner, K. W., Van Veld, R. D., (57) Hnslam, J., J . S c i . Instr. 35, 387 Wilkinson. P. G.. J . O p t . S o t . Am. (19) Casey, R. S., Perry, J IT., Berry, (1958). .\I. ll., Kent, A,, “Punched Cards: 48, 1001 (1958) (58) Haps, G., Tousey, R., J . Opt. SOC. (93) Meites, L., Thomas, H. C., “.4dTheir App!ications to Science and IndusAm.49,593(1959). vanced Analytical Chemistry,” l l c try,” esp. Part 11, Chap. 9, pp. 175-232, (59) Headridge, J. B., Talanta 1, 293 Gram-Hill, Xev %rk, 1958. Reinhold, New York, 1958. (1958). (94) hlellon, 31.G., Colorimetry,” Chap. 11’0) Chang, T. L., Karr, C., ANAL. V., J . Sci. Instr. 35, 371 (60) Heskcth, R C H E V . 30,971 (19%). 6, pp. 188-210, J. H. Yoe and H. J. (1958). Koch, eds., “Trace Analysis,” Kiley, (21) Chntterjee, I
