REVIEW OF FUNDAMENTAL DEVELOPMENTS IN ANALYSlS
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Ultraviolet Spectrophotometry
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ROBERT C. HlRT Research Division, American Cyanamid Co., Stamford, Conn.
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ropy in Applied Spectroscopy which lists current publications i n absorption spectroscopy but does not include abstracts. Recently, Odeen ( 9 4 ) has revised the “Bibliography of Applications of Beckman Spectrophotometers” to include articles up to June 1954. This bibliography covers visible absorption and flame photometry as well as ultraviolet absorption. Indexing is by subject matter, and titles, authors, and journal references are given but no abstracts. Unfortunately, there is no author index.
HIS biennial review covers the time elapsed since the last review on ultraviolet absorption spectrophotometry by Rosenbaum (106) until about the end of October 1958. I t is intended to be selective and critical rather than comprehensive, and as a result many worth-while papers on analytical spectrophotometry in the ultraviolet may not be mentioned. Publication of ultraviolet spectra in connection with structural, reactionrate, and other applications continued a t an increasing pace, as did papers of strictly analytical applications. As in past reviews, spectra published in connection with structure spectra correlations and description of compounds and reactions are not included.
PUNCHED CARDS
Committee E-13 of the hmerican Society for Testing Materials commenced the distribution of I B M punched cards coding ultraviolet absorption spectra from the literature. The chemical structural coding and other features follow those of the infrared cards whose distribution was started earlier. T h e codes and instructions for all ASTSI-IBM punched cards have been described in detail in a booklet prepared by the committee (3). The first issue of cards included 1284 cards, about 600 of which were prepa.red from spectra which appear in the Friedel and Orchin collection (39). -4second issue of cards should have appeared by the time of this review, also composed of spectra abstracted from t,he literature by a corps of volunteer abstractors. T h e compilation of this collection of spectral data, which includes not only current publications but data back a t least to the beginning of the “photoelectric era” (circa 1940), should, Ti-ithin a few years, permit literature fiearches to be done on I B l I niachines in very short times, instead of the presently nea:.ly impossible taslc in the library. This use may well become as important as the originally intended use of identification of unknowns.
BOOKS AYD REVIENS
h book b) Gillam and Stern (42)was solely concerned with ultraviolet absorption spectra. This test empirically correlates ultraviolet bands and chemical constitution and presents a large store of information, principally in the form of tabulated data and references. I t tends, however, somewhat to slight modern developments, in that considerable emphasis is placed on photographic techniques and that the bibliography extends only t o about 1951. Gould (48)and Brode ( 1 2 ) have revieived this book. Several books concerned with instrumental anal) sis have appeared; these (9, 35, 54) generally devote one or two chapters to ultraviolet spectrophotometry, and consequently suffer from this necessary brevity. Considerable emphasis is usually placed on instrumentation rather than on applications. 1701ume I1 of “Radiation Biology” (111) which deals with ultraviolet and related radiations contains a great deal of information not elsewhere I eadily available; the chapter on ultraviolet absorption spectra is particularly valuable. Revien s on the more theoretical side of ultraviolet spectroscopy (but ahich should he of considerable Forth t o the analvtical spectroscopist) have been written by Walsh (132) and by Sponer ( 1 1 4 ) in the 1954 and 1955 issues of the “Annual Review of Physical Chemistry.” A review by Orgel (95) covers the little known but significant field of charge-transfer spectra. Badger’s book (6) devotes a chapter to absorption and fluorescence spectra of aromatic compounds. Gunther and Blinn (61) list spectra of important insecticides.
INSTRUMENTS AND CELLS
I n this country, there are now a number of manufacturers of automatic recording spectrophotometers for use in the ultraviolet region. Applied Physics Corp. (Cary) has added the versatile model 14 to its line; it is an instrument featuring a double monochromator using both a grating and a prism and extending its useful spectral range from the near infrared down to about 1850 h. with a minimum of stray light (4). Beckman Instruments, Inc., has added a compact Model DK-2 to its previous DH-1, both instruments using the DU monochromator. Another recording spectrophotometer using the DU monochromator is made by Warren Electronics, Inc., and described by Royer and others (109). X universal spectrophotometer is now produced by Perhin-Elmer Corp., described by Coates, Miller, and Savitzky (22), using a fused silica prism in a Model 21 infrared instrument with a hydrogen source and photomultiplier detector. Several other recording attachments have been devised for the Beckman D U monochromator, such as that described by Nielsen (91). Water-prism monochromators have been built and tested by Fluke and Setlow (36). An interesting variation on means for measuring ultraviolet radiation lyas presented by Price and Hudson (103) by applying a halophosphate fluoroscope and a Geiger tube which was sensitive only to short ultraviolet radiation to the measurement of
BIBLIOGRAPHIES AND INDEXES
This class of “literature about literature” has its value in keeping the reader informed about articles of interest which appear in publications that he does not ordinarily read. Mellon (86) has discussed the literature problem in general. T h e new British journal, Analytical Abstracts, gives comprehensive coverage of analytical articles and excellent abstracts. Articles using spectrophotometry may appear under almost any classification, however, so all categories need t o be checked. The British quarterly, British Bulletin of Spectroscopy, devotes half its space to molecular spectroscopy, a good share of which is pertinent to analytical applications of ultraviolet spectrophotometry. Prescott (102) supplies an indev t o articles of applied spectros-
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tile :disorption of chromatograms. The detector ignored visible and long wave-length ultraviolet and was capable of measuring high absorbances. -4 double-compartment cell was used by Rlitzner and Lewin ( 8 9 ) for studying interactions between substarices using infrared, b u t the principle is also applicable t o ultraviolet work. Similarly, short path infrared cells were described by Hochheimer and Moore (63) %-hich could also be used in the visible or ultraviolet’ regions. Mitzner ( 8 8 ) utilized infrared cells t o obtain the ultraviolet spectra of pure liquids, thereby avoiding solvent effects. Another device designed for other spectral regions but usable in the ultraviolet is the reflect,ing objective for microspectrophotometry of Thornburg (122). A versatile low- or high-temperature cell for the Cary spectrophot,ometer was described by Geiger ( 4 0 ) ; Hamner, Hadden, and Padgett (53) devised a 50-cm. heated gas cell for use with the Cary. Inserted materials have been used to reduce volumes of Beckman cuvettes (113). A “dry calibration” technique for absorption cells was advocated by Archer ( 5 ) . Wyman ( 1 3 7 ) surcessfully applied potassium bromide disks to obtaining ultraviolet spectra with the Cary spectrophotometer by use of a special disk holder. Vandenbelt and others ( 1 8 8 ) showed that t,here is a constituent of human perspiration with st.rong ultraviolet absorption which could cause errors if deposited on cell window. The newest recording spectrophotometers (Cary 14, Beckman DII-1 and DK-2, Spectracord, and Perkin-Elmer Universal) are too recent for comparative studies t o have appeared. However, two intercomparison studies of Cary Model 11 spectrophotomct,ers were carried out by volunteers from members of the American Drug Manufacturers Association. T h e first of t,hese, described by Vandenbelt (I%’), used calibrated glass filters for intercomparison in the visible region, while the second (131) used chromate solutions in the ultraviolet. Very good agreement m-as found among the instruments. Another study by Iietelaar and others ( 7 2 ) covered one Cary and one Zeiss and several Beckman instruments; good agreement was found, even though the slit widths used varied widely among the various instruments. Tarrant ( 1 1 8 ) described the operation and performance of a Cary spectrophotometer a t the National Physical Laboratory (England). Most recently, Cahn (16) presented a n article on photometric reproducibilit’y betiveen ultraviolet spect,rophotometers, which was largely a comparison of the Cary 11 and Beckman DE instruments. While avoiding the current controversy between the proponents and opponents of differential spectrophotometry, Cahn presented some signifirant data and comment,s regarding t,he real precision of epectrophotometric measurements by conventional means. BEER‘S LAW
The law of the absorption of electromagnetic energy, generally called Beer’s la^, which is the basis of quantitative spectrophotometry, >vas given a variety of usual and unusual applications. Perhaps fewer alleged “deviations” from this law have found their way into print these two years because, i t is hoped, of a better awareness of the validit,!- of this law and of the “app:trent” deviations due t o scattered light, fluorescence, instrumental and operational defects, and errors in counting the number of absorbing Epecies present. .4 valuable contribution to the interpretation of absorption curves which result from overlapping bands was made by Vandenbelt and Henrich (129), who present,ed plots of idealized curves n-hich had been added together; these covered a broad range of relative band intensities and separations. Most recent,ly, Giese and French ( 4 1 ) have offered a method of analyzing such overlapped absorption curves by plotting the first derivative of absorbance as a function of wave length. Several graphical illustrations were presented and a n instrumental method of plotting was promised; considerable experimental evaluation is needed. An “absorbance-ratio” method for ease in setting up t a o - and three-component analyses was described ( 6 8 ) . Ross (108)
discussed Beer’s law for conditions of samples of nonuniform concentration and of irradiated glasses. The temperature dependence of absorbance was studied by Yarborough, Haskin, and Lambkin (158). Stray light originating from internal reflections in prisms was discussed ( 5 2 ) . Tunnicliff (124) presented a study of the measurement of nearby stray light in ultraviolet spectrophotometers, in contrast to the usual general st,rap light studies. For this, t h e extremely sharp absorption of the 2537 A. line by heated mercury vapor in a sealed cell was utilized. Interest in the experimental measurement of stray light in modern spectrophotometers is most encouraging in viev of the tendency to make use of high absorbance readings and to use high absorbance blanks. Measurements are being pushed to the lowest possible wave length limits, especiall?. with the advent of fused silica optics having better transmitt,ance a t very short v a v e lengths (used in several nen- instruments). A most interesting experiment, which could be tried by everyone owning any kind of spectrophotometer, is that of Jfehler ( 8 5 ) , who used a series of samples prepared to have absorbances of 1, 2, 3, 4, and 5 a t a particular wave length. These were esamined successively, starting with the A = 1 using a solvent blank and using each sample v-ith its preceding sample as a blank; thus each sample should have given an instrumental reading of 1 absorbance unit. The results are something t h a t every advocate of using high absorbance blanks in differential spectraphotometry must consider. httention should also be called to a brief (but most pertinent) editorial on the topic of reproducibility (101). Two articles on the fluorescence error in spectrophotomet’ry, one by Ovenston ( 9 6 ) and another by Braude and Timmons ( I O ) , are important. More recently, Gridgeman (50) presented a critical discussion on precision and errors in differential spectrometry, and Cannon ( I ? ) reported an anomalous error encountered in this technique, whereby t,he ahsorptivit,y appeared to increase rat,her than decrease with slit width. Reilley and Crawford (104) discuss the principles of precision colorimetry and some possible errors. An unusual variation of the differential method, presented by Lot,he ( 8 0 ) , is called indirect differential spectrophotometry; this was published rather too recently for experimental evaluations or eritirisms to appear. SPECTROPHOTO.IlETRIC TITRATIONS
Recording ultraviolet spectra as a function of p H or of amount of titrating solution added may be used to determine ionization ronstantp, to perform quantitative analyses for the material being titrated, or to make use of an absorbing material as an “ultraviolet indicator” for t,he titration of some transparent material. Several devices for making t.hcse operations easier and faster have been described. A “spectrotitrimeter” ( 7 3 ) , using a glass-piston pump to circulate the solution through t h c absorption cell of a Cary spectrophotometer and titration vessel, included a tlierniostating arrangement and displacement of air n-ith an inert gas. Fricker (58)described a somewhat simpler devire n-bLichuses a high- speed glass centrifugal pump to circulate the solution about a compact system. This apparatus was for use in visible spectrophotometry, but n-it,h quartz cells it would be applicable to ultraviolet as well. h titration assembly ( 7 5 ) for a Beckman DU used a magnetic stirrer within a titration vessel which was also the absorption cell. A comparison of p H values determined by electrometric titration and by ultraviolet absorption methods showed good agreement bet\\-een the two methods (130). A method for calculating dissociation constants from spectrophotometric data has been described by Rosenblatt ( I O $ ) , which is applicable where it is impossible to determine absorptivities of the pure ionic or molecular forms. Thamer (121) described means of determining overlapping pk‘, values of dibaeic acids n-hich did not require direct knowledge of the individual ionic forms. Irving, Rassotti,
V O L U M E 28, NO. 4, A P R I L 1 9 5 6 and Harris (67) discussed extensively a general method for calculating pK, values based on points of inflection of a p H us. absorbance curve. h chart of pK ranges for various ionizable organic groups was presented along n i t h a discussion of the use of apparent dissociation constants in qualitative organic a n a l y k (98). h review (44)on photometric titrations contained 105 references and ’ivas devoted largely to visible spectrophotometry b u t also covered ultraviolet applications. Extension to photometric titrations of nonaqueous solvents (106) ITas made n ith glacpial acetic acid 21s the medium. Use of a typical “ultraviolet indicator” was made (82) in the automatic titration of thorium, using copper I-ersenate and a Car)- spectrophotometer plotting absorbance L’S milliliters of titrant. \. 4CLU\1 L LTRAkIOLET
Xlthough the vacuum ultraviolet region is not a t present considered a n important region for quantitative analysis, as most commercial instruments are capable of accurate measurements t o only about 2200 A,, i t is expected t o become important soon. I n n (65) has reviewed the literature on this spectral region, and Jones and Taylor ( 6 9 ) have summarized data in the 1700 to 2200 .4.region and term this region a “promising new tool for the analyst.” Klevens and Platt (74) collected their measurements and some of others into the largest compendium of vacuum ultraviolet spectra extant. T h e wave-length “guideposts” from 1940 $. down t o 875 A. have been mapped in a paper on provisional wave-length standards in the vacuum ultraviolet by Wilkinson (135). Ken- photon counters for use in this spectral region have been described by Chubb and Friedman (20). A novel instrument, measuring down t o 1500 -4.( 6 2 ) features a fluorite prism which is vibrated about a horizontal axis while scanning about a vertical axis in order t o minimize scattered light effects. A new xenon arc has been described as a source for the vacuum ultraviolet (136). INORGANIC ANALYSIS
Some trends in the application of ultraviolet spectrophotonietry seem apparent, such as a tendency t o choose a stronger ult,raviolet band for the analytical wave 1engt.h rather than a visible wave-length band in order to obtain bet’ter sensitivity (lower detectability); this is sometimes referred t o by the term “ultraviolet colorimetry” ( which is a n unhappy mongrelization of terms t o many spectroscopists). There is also a trend toward using complesing agents, notably ethylenediaminetetraacetic acid [(ethylenedinitrilo)tetraacetic acid, EDT.41. Buck, Singhadeja, and Rogers ( 1 4 ) have summarized common anions which absorb ultraviolet themselves or as complexes n-ith metals. Determinations of arsenic, phosphorus, and silicon ( 2 7 ) and of soluble silicates ( 2 6 ) are reported. Siobium has been determined directly in hydrochloric acid (YO),as thiocyanate complex (55), and as a derivative of 8-quinolinol ( 7 1 ) . Tellurium sols ( 6 8 ) are determined at 280 mp in preference to a visible band because of the variation of t,he latter with part,icle size; telluric acid is determined directly (112). I’j-rogallol was used to determine tantalum (29) and to determine tantalum and niobium in ores (84). Palladium ( I S ) , niercurJ- (83), and vanadium (47)are other examples. For EDT.4 complexes, a sampling of tmheliterature shov-ed a summary for five elements ( 1 1 7 ) , bismuth determined near 400 mp (19, 125) 134), and determinations of iron (90, 126). One of these procedures for iron (90) was developed as a microprocedure claimed to be good d o n n to 4 p.p.m. Many other metal determinations by complesing agents and spectrophotometry have been reported; a n interesting application of these is as “ultraviolet indicators” for titration performed t o determine some other substance. An indirect method was applied to the determination of small amounts of oxygen in water, by making use of the strong absorption of the t’riiodide ion at 353 mp ( 9 7 ) . For analyzing
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oxides of nitrogen, nitrogen dioxide and nitrogen tetroxide are determined at 394 mp and the other components by mass sp(:ctrometry (92). ORGANIC ANALYSIS
I n viewing the tremendous growth which has taken place in the field of ultraviolet spectrophotoniet,ric determination of organic compounds, one is impressed with the t’rend to employ solventsolvent extractions, precipitations, romplexing agents, chemical separations, or chromatography as a n inherent part of the analytical scheme. These serve to rid t,he material to be analyzed of substances which have overlapping absorptions, t o concentrate the desired material to obtain a lower detectability, or generally t,o make a simple analysis out of a hopelessly complex one. Many analytical schemes are now dependent upon chemical solvent or chromatographic separations prior t o spectrophotometric identification or quantitative anal>&. I n some applications t,he change in observed spectra with changes in p H or aolvent may be utilized. Some of the following examples may he used as illust.rations. By the use of selective solvent extractions, curing agents i n rubber products may be identified (76). Lacquers may have nitrocellulose and phthalate esters analyzed (116). Extraction permitted the determinat,ion of nicotinic acid in tobacco leaves ( 3 7 ) and t,he conjugated acid cont,ent of milk f a t (77),for example. Separations prior t,o spectrophotometric analysis permitted the determination of alkaloids in opium (31). Acc~cblerators and ant,ioxidants in rubber products were detrrniined hjBrock and Louth (11). I n recent years, the natural cooperation between spectrophotometry and chromatography has changed from the use of the spectrophotometric methods for t’he monitoring of chromatographic column effluents into the incorporation of chroniatographic separations as intrinsic parts of analytical schemes to effect separations prior to spectrophotometric examinations. While the analysis of column effluent will continue to be an important, application of ultraviolet spectrophotometry, the preliminary separations \vi11 become increasingly important t o the analyst. Some exampks of this include the detection of antioxidants in rubber stocks (62), theobromine and caffc.ine in cocoa (35), pyret,hin synergists (E), vitamins h and D ( 1 3 , 34, 79),mixtures of phenols (99), and a-keto acids in blood a n d urine (119). Such separations were discussed by Crowe and Walker (24). Cooper ( 2 3 ) applied chromatographic separations to the determinations of polycyclic hydrocarbons in city air. -4similar application to effluents from gasnorks n-as made (133). Some examples of spectral shifts viith p H which were uscd in analytical schemes werr the Ti-ork of Goldschmid ( 4 6 ) on lignin, the distinction of morphine from codeine (21 ), Meyer’e investigations on steroids ( 8 7 ) , and the determination of erythromycin by application of alkaline hydrolysis and an acidic blank (120). T h e acid hydrolysis of melamine resins to melamine a t reflux temperatures was used in the analysis of wet-strength paper (59). Shifting the p H of the eolution being examined permitted the determination of tetracycline, oxytetracycline, and rh1ortetr:tcycline a t t,hree n-ave lengths and three p H values (66). The shift of the spectra of phenols with variations in p H n-:is (-omhined n.ith a chloroform separation in analyzing waste ivators ( 1 1 0 ) . h similar use of p H shifts of absorption spectra was employed by Goldman (.i5) in determining nicotinic acid hydrazid. -4hlei-s :tnd O’Xeill ( 1 ) reviewed the structure of oils and resins as determined by spectroscopy. Stafford, Shay, and Francel ( 1 1 6 ) presented the infrared and ultraviolet ahsorption spcctra of the more important dicarboxylic acids for purposes of identification in the analysis of resins. r s i n g the Iiappelmeier separation method, as modified by the American Society for Testing Materials ( 2 ) , styrenated fatty acids and alkyd resins were analyzed spect,rophotometrically ( 6 1 ) . Herb ( 5 7 ) reviewed the application of ultraviolet spectrophotometry to the anal!-&
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of fats, giving 56 references. Davis and Bowen ( 2 5 ) combined a titration with spectrophotometry t o effect the analysis of benzoate and phthalate esters on military clothing. Aromatic sulfonates were determined following an acid-ether extraction in analyzing synthetic detergents ( 6 4 ) . Total and primary hydroxyl were determined ( 8 1 )in cellulose by the use of reactions to produce ultraviolet-absorbing substances. Styrene and phthalate esters were determined in polvester resins (60) and fumarate and glycols estimated. Complexes with iodine were effectively employed in the analysis of aliphatic sulfides (30, 66). Long and Neuzel (78) demonstrated t h a t the observed absorbance of iodine complexes with olefins was proportional to the product of the iodine and olefin concentrations. They showed that the wave-length position of the band varied with the number of substituents about the carbon atoms of the olefinic double bond. A large table of examples was presented. The weak absorption of the ketone group near 290 mp was exploited in the determination of combined methyl isopropenyl ketone in polymers by Pepe, Iiniel, and Czuha (100).
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MISCELL4NEOUS
Installation of a Beckman D U R for automatic control in a synthetic rubber plant was described ( 2 6 ) . Ballard and coworkers ( 7 ) showed t h a t corrections could be made for interferences from absorbing organic substances in a Beckman D U used as a 2537 A . gas analyzer because of the sharp absorption line of mercury in contrast t o the broad organic adsorption bands. Glasser ( 4 3 ) described an automatic ultraviolet gas analyzer with a variety of filter combinations t o change the effective analytical wave length in order to provide a variety of possible analyses. Application t o continuous analysis of gas streams was made. Troy ( I d s ) used a portable gas analyzer for measurement of atmospheric pollution; this device is now commercially available and should be most useful. The purification of fluorocarbon liquids was followed spectrophotometrically by Grafstein ( 4 9 ) ; this suggests possible use of these compounds as solvents for ultraviolet spectrophotometry. D a t a on conjugated terpene hydrocarbons presented by O’Connor and Goldblatt (93) should prove valuable for setting up analytical schemes. The protection of light-sensitive pharmaceutical preparations is discussed by Dimbleby (28) and transmittance curves for a number of colored glasses used for bottles are presented, with data extending down to about 300 mp. LITERATURE CITED (1) Ahlers, N. H. E., O’Neill, L. A., J . Oil &. Colour Chemists, Assoc. 37, 533 (1954). (2) Am. SOC.Testing Materials, Philadelphia, Pa., ASTN Method D563, ASTAI Standards, P t . 4 , 332, 1952. (3) Am. SOC. Testing Materials, Philadelphia, Pa., Committee E-13, “Codes and lnstructions for Wyandotte-dSTM Punched Cards Indexing Spectral A4bsorptionData,” 1954. (4) Applied Physics Corp., Pasadena, Calif., Bull. ACS 7, A x . 4 ~ . CHEM.27 (So. 9 ) , 48A (1955).
(5) Archer, 11. S., Photoelectric Spectrometry Group Bull., S o . 7, 160 (1954). (6) Badger, G. AI., “Structurer and Reactions of the Aromatic Compounds,” Chap. 10, Cambridge University Press, Cambridge, 1954. (7) Ballard, A . E., Stewart, D. W.. Kamm, K,O., Zuehlke, C. W., Ah-AL. C H E Y . 26, 921 (1954). (8) Beroaa, AI., Ibid., p. 1173. (9) Braude, E. A,, Nachod, F. C., “Determination of Organic, (10) (11) (12) (13)
Structures by Physical Methods,” Academic Press, New York, 1955. Braude, E. A , , Timmons, C. J., Photoelectric Spectrometry Group Bull., NO. 6, 139 (19533. Brock, A f . J., Louth, G. D. ANAL.CHEx 27, 1575 (1955). Brode. W.R.. J . Ont. Soc. A m e r . 45. 1000 (1955). Bro-Rasmussen, F.; Hjarde, W., Poiotnikoff. O., A n a l y s t 80,
418 (1955). (14) Buck, R. P., Singhadeja, S., Rogers, L. B., A N A L . CHEM.26, 1240 (1954).
(15) Cahn, L . , J . Opt. Soc. A m e r . 45, 953 (1955). (16) Campbell, G. C., Godin, J. B., I n d . Eng. Chem. 46, 1413 (19.54). (17) Cannon, C. G., Photoelectric Spectrometry Group Bull., No. 8 , 2 0 1 (1955). (18) Cheng, K. L., ANAL.CHEY.26, 1894 (1954). (19) Cheng, K. L., Bray, R. H., Nelsted, S. Vi’.,Ibid., 27, 24 (1955). (20) Chubb, T. A., Friedman, H., Rev. Sci. Tnstr. 26, 493 (1955). (21) Clark, W.A., McBay, A. J., J . Am. P h a r m . Assoc.. Sci. E d . 43, 39 (1954). (22) Coates, V.,Miller, T., Saviteky, A , , A ~ p l Spectroscopy . 9 , 14 (1955). (23) Cooper, R . L., Analyst 79, 573 (1954). (24) Crowe, AI. O’L., Walker, A., A p p l . Spectroscopy 8 , 57 (1954). (25) Davis, P. L., Bowen, C. V., ANAL.CHEY.27, 1233 (1955). (26) DeSesa, A l . A., Rogers, L. B., Ibid., 26, 1278 (19.54). (27) Ibid., p. 1381. (28) Dimbleby, V., J . P h a r m . and Pharmacol. 5, 969 (1953). (29) Dinnin, J. I., AXAL.CHEm 25, 1803 (1953). (30) Drushel, H. V., Miller, J. F., Ibid., 27, 495 (1955). (31) Dyer, 11. S., JIcBay, A. J . , J . A m . P h a r m . Assoc.. Sci. Ed. 44, 156 (1955). (32) Einhorn, H. D., Cohen, A. E. Z., J . O p t . Soc. A m e r . 44, 232 (1954). (33) Englis. D. T., Niles, J. W., ANAL.C m Y . 26, 1214 (1954). (34) Ewing, D . T., Schlabach. T. D., Powell, 11.J., Vaitkus, J. W., Bird, 0. D., Ibid., p. 1406. (35) Ewing, G. W., “Instrumental Methods of Chemical Analysis,” 11cGraw-Hill, New York, 1954. (36) Eluke, D . J., Setlow, R. B., J. Opt. Soc. -4mer. 44, 327 (1954). (37) Frankenburg, W.G., Gottscho, A . JI., Kissinger, S., Bender, D., Erlich, D., ANAL.CHEM.25, 1784 (1953). (38) Fricker. D . J., Chemistry & I n d u s t r y 16, 426 (1955). (39) Friedel, R. A., Orchin, AI., “Ultraviolet Spectra of Aromatic Compounds,” Wiley, Sew York, 1951. (40) Geiger, F. E., Jr., Reu. Sei. I n s t r . 26, 383 (1955). (41) Giese, A. T., French, C. S.,A p p l . Spectroscopy 9, 78 (1955). (42) Gillam, A . E., Stern, E. S., “An lntroduction to Electronic Absorption Spectroscopy,” Edward Arnold, London, 1954. (43) Glasser, L. G., J . Opt. Soc. A m e r . 45, 556 (1955). (44) Goddu, R. F., Hume, D. N., ANAL.CHEY.26,1679, 1740 (1954). (45) Goldman, D. S., Science 120, 315 (1954). (46) Goldschmid, O., ANAL. CHEM.26, 1421 (1954). (47) Gottlieb, I. II.,Hazel, J. F., 11cSabb. W.>I., A n a l . Chim. A c t a 1 1 , 376 (1954). (48) Gould, J., A N A L . CHEY.27 (So. l ) , 2 4 h (1955). (49) Grafstein, D., Ibid., 26, 523 (1954). (50) Gridgeman, N.T., Photoelectric Spectrometry Group Bull., S o . 8, 197 (1955). (51) Gunther, F. .4..Blinn, R. C., “Analysis of Insecticides and
Acaricides,” in “Chemical Anslysis,” B. L. Clarke and I. 11. Kolthoff, eds., Vol. 6, Interscience, New York, 1955. (52) Hammond, V. J., Price, W. C., J . Sci. I ~ s ~31, T .104 (1954). (53) Hamner, W. F., Hadden, N.,Padgett, W. AI., A s . 4 ~ .CHEM. 27, 747 (1955). (54) Harley, J. II., Wiberley, S. E.. “Instrumental .Inalysis,” Chaps. 2, 4, Wiley, New York, 1954. (55) Hastings, J., McClarity, T. A . , .AN.~L. CHEM.26, 683 (1954). (56) Hastings. S. H., Johnson, B. H., Ibid., 27, 564 (1955). (57) Herb, S. F., J . Am. Oil Chemists’ Soc. 32, 153 (1955). (58) Hirt, R. C.. King, F. T., Schmitt, Ii. G., ASAL. CHEY.26, 1270 I1..._ 9.54). _
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(59) Ibid., p. 1273.(60) Hirt, R. C., Schmitt, R. G., Stafford, R. R.,Ibid., 27,354(1955). King, F. T., Schmitt, R. G., Ibid., (61) Hirt, R.C., Stafford, K. W., p. 226. (62) Hively, R. -4., Cole, J. O., Parks, C. R., Field, J. E., Fink, R., Ibid., p 100. (63) Hochheimer, B. F., Moore, G. E., J . Opt. Soc. A m e r . 45, 891 (1955). (64) House, R., Darragh, J. L., A N A L . CHEY. 26, 1492 (1954). (65) Inn, E. C. Y., Spectrochim. Acta 7 , 65 (1955). (66) Intonti. R., Cotta-Ramasino, F., Ann. chim. ( R o m e ) 44, 437 f 1954). (67) Irving, H., Rassotti, H. S., Harris, G., Analyst 80, 83 (1955). (68) Johnson, R. A., Andersen, B. R., ABAL.CHEM.27, 120 (1955). (69) Jones, L. C., Jr., Taylor, L. W., Ibid., p. 228. (70) Kaneelmeyer, J. H., Freund, H., Ibid., 25, 1807 (1953). (71) Kassner, J. L., Garcia-Porrata, A., Grove, E. L., Ibid., 27, 492 (1955). (72) Katelaar, J. A . A, Fahrenfort, J., Haas, C.. Brinkman, G. A, Chem. Weebblad 51, 211 (1955) ; Photoelectric Spectrometry Group Bull., S o . 8 , 176 (1955). (73) King, F. T., Hirt, R. C., A p p l . Spectroecopy 7 , 164 (1953). (74) Klevens, H. B., Platt, J. R., “Survey of Vacuum Ultraviolet Spectra,” Tech. Rept. OXR Contract N60RI-20, Task Order IX, Project NR 019 101.
V O L U M E 28, NO. 4, A P R I L 1 9 5 6 (75) Klingman, D. W., Hooker, D. T., Banks, C. V., ANAL.CHEnr. 27, 572 (1955). (76) Kress, K. E., llees, F. G. S.,ANAL.CHEM.27, 528 (1955). (77) Lemhke, A., Kaufmann, W., Milchwissenschaft 9, 113 (1954); J . Am. Oil Chemists’ SOC.32, 115 (1955). (78) Long, D. R., Keuzel, R. W., A N A L . CHEM.27, 1110 (1955). (79) Lord, J. W., Bradley, P. ll.,A n a l y s t 80, 429 (1955). (80) Lothe, J. J., ASAL. CHEW27, 1546 (1955). (81) Malm, C. J., Tanghe, L. J., Laird, B. C., Smith, G. D., Ibid., 26, 188 (1954). (82) llalmstadt, H. V., Gohrbandt, E. C., Ibid., p. 442. (83) Xlarkle, G. E., Boltz, D. F., Ibid., p. 447. (84) Xlarzys, A. E. O., A n a l y s t 80, 194 (1955). (85) Xlehler, A. H., Science 120, 1043 (1954). (86) llellon, hl. G., .4N.4L. CHEM.26, 181 (1954). (87) l k y e r , A. S., J . Org. Chem. 20, 1240 (1955). (88) llitzner, B. lf.,J . Opt. SOC.A m e r . 45, 997 (1955). (89) Mitzner, B. AI., Lewin, S. Z., Ibid., 44, 499 (1954). (90) Kielsch, W., and Boltr, G., Microchim. A c t a 1954, 481. (91) Nielsen, S. O., Rev. Sci. I n s t r . 26, 516 (1955). (92) Norris, XI. S.,Fleck, S. A, Lichtenfels, D. H., ANAL.CHEM., 27, 1565 (1955). (93) O’Connor, R. T., Goldhlatt, L. A., Ibid., 26, 1726 (1954). (94) Odeen, XI., Beckman Instruments, Inc., Fullerton, Calif., B e c k m a n B u l l . 222-C (1955). (95) Orgel, L. E., Quart. Revs. ( L o n d o n ) 8 , 422 (1954). (96) Ovenston, T. C. J., Photoelectric Spectrometry Group Bull., S o . 6, 132 (1953). (97) Ovenston, T. C. J., Watson, J. H. E., A n a l y s t 79, 383 (3954). ANAL. CHEM.26, 642 (1954). (98) Parke, T. V., Davis, W. W., (99) Pearson, R. Xl.. A n a l y s t 80, 656 (1955). (100) Pepe, J. J., Kniel, I., Czuha, AI., ANAL. CHEY.27, 755 (1955). (101) Photoelectric Spectrometry Group. Bull., KO.7, 168 (1954). (102) Prescott, B. E., A p p l . Spectroscopy 7 , 200 (1953); 8, 46, 96, 146 (1954); 9, 49 (1955). (103) Price, T . D., Hudson, P. B., ANAL.CHEY.26, 1127 (1954). (104) Reilley, C. N.,Crawford, C. ll.,Ibid., 27, 717 (1955). (105) Reilley, C. N., Schweizer, B., Ibid., 26, 1124 (1954). (106) Rosenhaum, E. J., Ibid., p. 20. (107) Rosenblatt, D. H., J . P h y s . Chem. 58, 40 (1954). (108) Ross, I. G., J . Opt. SOC.A m e r . 44, 40 (1954). (109) Royer, G. L., Lawrence, H. C., Kodama, S. P., and Warren, C. W., ANAL.CHEY.27, 501 (1955). (110) Schmauch, L. J., and Gruhh, H. ll.,Ibid., 26, 308 (1954).
583 (111) Scott, J. F., Sinsheimer, R. L., in “Radiation Biology,” -4. Hollaender, ed., Vol. 11,Chaps. 4,5, AlcGraw-Hill, Kew Tork, 1955. (112) Scott, L. Leonard, G. W.., ANAL.CHEY.26, 445 (1954). (113) Sharpe, L. H., Ibid., p. 1528. (114) Sponer, H., in “Annual Review of Physical Chemistry,” G. K. Rollefson and R. E. Powell, eds., Vol. 6, pp. 193-216, Annual Reviews, Inc., Stanford, Calif., 1955. (115) Stafford, R. W., Shay, J. F., Francel, R. J., ANAL.CHEY.26, 656 (1954). (116) Swann, 31. H., Adams, 11. L., Esposito, G. G., Ibid., 27, 1426 (1955). (117) Sweetser, P. B., Bricker, C. E., Ibid., 26, 195 (1954). (118) Tarrant, -4. W. S.,Photoelectric Spectrometry Group Bull., S o . 6, 143 (1953). (119) Taylor, K. W., Smith, 31. J. H., A n a l y s t 80, 607 (1955). (120) Tepe, J. B., St. John, C. V., A N ~ LCHEM. . 27, 744 (1955). (121) Thamer, B. J., J . P h y s . Chem. 59, 450 (1955). (122) Thornburg, W., J . Opt. SOC.A m e r . 45, 740 (1955). (123) Troy, D. J., -4NAL. CHEM.27, 1217 (1955). (124) Tunnicliff, D. D., J . Opt. SOC.A m e r . 45, 963 (1955). (125) Underwood, -4.L., . ~ N A L . CHEW26, 1322 (1954). (126) Uzumasa, Y., Kishimura, AI., B u l l . Chem. SOC.J a p a n 28, 88 (1955). (127) Vandenhelt, J. AI., J . Opt. SOC.A m e r . 44, 641 (1954). (128) Vandenhelt, J. 11., Childs, C. E., Lundquist, D., Saladonis, J., Science 119, 514 (1954). (129) Vandenhelt, J. AI., Henrich, C., April. Spectroscopy 7, 171 (1953). (130) Vandenhelt, J. JI., Henrich, C., Yandenberg, S. G., A N . ~ L . CHEY.26, 726 (1954). (131) Vandenbelt, J. AI., Spurlock, C. H., J . Opt. S o t . A m e r . 45, 967 (1955). (132) Walsh, A. D., and Duncan, A . B. F., in “Annual Review of
w-.,
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Wedgewood, P., Cooper, R. L., Analyst 80, 652 (1955). West, P. W., Coll, H., ANAL.CHEY.27, 1221 (1955). Wilkinson, P. G., J . Opt. SOC. A m e r . 45, 862 (1955). Wilkinson, P. G., Tanaka, Y., Ibid., 45, 344 (1955). Wyman, G. AI., Ibid., 45, 965 (1955). Yarhorough, V. s l . , Haskin, J. F., Lambkin, \V. J., .INAL. CHEM.26, 1576 (1954).
I REVIEW OF FUNDAMENTAL DEVELOPMENTS IN
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X-Ray Absorption and Emission
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HERMAN A. LIEBHAFSKY and EARL General Electric Co., Schenoctady, N. Y.
HE popularity of analytical methods based upon x-ray emis-
sion and absorption, and upon t h e analogous ?-ray processes, continues t o grow. T h e meetings during t h e past 2 years at which such methods were discussed are too numerous t o list. Abstracts of the Pittsburgh Conference papers (6-8)provide a fair index t o progress in this field and t o the material presented a t other conferences. T h e present revieF will be easier t o follow n-ith these abstracts arid the earlier reviews (88-93) a t hand; references t o the individual abstracts are not in general made here. An event of first importance t o all those interested in using x-rays is the appearance, considerably expanded in its fourth edition, of Clark’s “Applied 9-Rays” (31 ). I n the present review, two important topics-detectors and histochemical analysis-have been given more extended treatment than the others. -in attempt has been made t o present enough about t h e absorption and emission of -/-rays t o inform
H. WINSLOW
the analytical chemist usually concerned with what happens outside the nucleus. T h e bibliography falls far short of including all t h e references, especially all the ?-ray references, compiled in preparing t h e review. * DETECTORS
T h e subject of x-ray and ?-ray detection belongs primarilj- to the physicist. T h e analytical chemist must take notice of it, however, because the detectors concerned are now among the tools of his profession. Were it not for the great improvements t h a t have occurred in these detectors during the past 15 years, there would be little or no occasion for these reviews. T h e information about detectors in Table I is perhaps a reasonable minimum for the analytical chemist; further information is available (14, 46, 50, 75, 131, 143). T h e photographic plate, though invaluable for specialized
