V O L U M E 2 2 , NO. 1, J A N U A R Y 1 9 5 0 (23) Deloume, F. E., and Holmes, J. R., P h y s . Rev., 76, 174 (1949). (24) Enns, J . H., and Wolfe, R. A,, J . Optical S O C .Am., 39, 298-304 (1949). (25) Everling, IT7. D., Steel, 124, 80-1, 116 (1949). ( 2 6 ) Fasael, 5’. A . , J . Optical Soc. Am., 39, 187-93 (1949). (27) Fernando, I., Current Sci., 17, 362 (1948). (28) Fetterley, G. H., and Hazel, IT’. M., J . Optical SOC. Am., 39, No. 12 11949). 129) Fowles, G. R., P h y s Rev., 74, 219 (1948). (30) Ibid., 76, 571 (1949). 131) Fred, hl., Tomkins, F. S.,and Brody, J. K., I b i d . , 75, 1772 (1949). 32) Gatterer, ri., Spectrochim. A c t a , 3, 214-32 (1948). 33) Gatterer, -4., and Junkes, J., “Atlas der Restlinien,” Specola Vaticana. Citta del Vaticano, 1937-49. (34) Green, J. B.. and Maxwell, H. N . , P h y s . Rev.,74, 1208 (1948). (35) Gurevitch, M., and Teasdale, J. G., I b i d . , 76, 151 (1949). 36) Harrison, G. R., Lord, R. C., and Loofbourow, J. R., “Practical Spectroscopy,” Kew York, Prentire-Hall Publishing Corp., 1948. 87) Harting, D., and Klinkenberg, P. F. A , Physica, 14, 669-83 (1949). Hasler, M .F., J . Optical SOC.Am., 39, Yo. 12 (1949). Hasler. M . F., Lindhurst, R. W., and Kemp, J. R’., Ibid., 38, 789-99 (1948). Herdle, A. J., and Wolthorn, H. J., ANAL.CHEM.,21, 705 (1949). Hirschberg, J. G., and Mack, J. E., B u l l . Am. P h y s . SOC.,24, No. 7, 12 (1949). Hirt, R. C., and Nachtrieb, N. H., A i i . 4 ~ .CHEY.,20, 1077-8 (1948). Huldt, L., A r k i v M a t . Astron. F y s i k , 36A, KO.3 (1948). Humphreys. C. J., J . Optical S O C .A m . , 39, S o . 12 (1949). Hustler. J. M . , and Hammaker, E. M . , A s . 4 ~ .CHEM.,21, 919 (1949). Irish, P. R., Open Hearth Steel, 31, 143-51 (1948). Jensen, D. P., I r o n A g e , 161, 66-8 (1948). Kelley, F. M., Schawlow, A. L., Gray, W.M . , and Crawford, M. F., B u l l . Am. P h y s . SOC.,24, No. 7, 13 (1949). Kiess, C. C., unpublished data. Kiess, C. C., Harrison, G. R., and Hitchcock, J. P., J . Research S a t l . BUT.Standards, in press. Kiess, C . C . , and Shortley, G., Ibid., 42, 183-207 (1949). Klinger, P., and Schliessmann, O., Arch. Eisenhottenw., 20, 21928 (1949). Koch, J., and Rasmussen, E., P h y s . Rev., 76, 1417 (1949). Kopfermann, H., and Paul, W., N a t u r e , 162, 33 (1948). Kopfermann, H.. and Wessel, G., -?‘achr. A k a d . W i s s . Go!tinoen. 1948. 53-5. Krate, G. R.. P h y s . Rev., 75, 1844-50 (1949). Kratz, H. R., and Mack, E. J., I b i d . , 76, 173 (1949). Krishnamurtv, S. G., and Fernando, I., I n d i a n J . Phus.. 23, 1724 (1949). Krikhnamurty, S . G., and Parthasaradby, T. V.,Il’ature, 164, 407 (1949). Lamb, W.E , and Retherford, R. C., P h y s . Rev., 72, 241-3 (1947); i 5 , 1332 (1949). Langbtroth ‘2. O., and Andrychuk, D., C a n . J . Research, 26A, 39-49 11948). Mack, J. E., and Arroe, 0. H., P h y s . Rev., 76, 173, 1002 (1949). KcNally, J. R., Jr., Am. J . P h y s . , 16, 409 (1948). McNally, J. R , , Jr., J . Optical SOC.Am., 39, 271-4 (1949). hlrNally, J. It., Jr., and Harrison, G. R.. Ibid., 39, 636 (1949). hIcSally, J. R., Jr., Molnar, J. P., Hitchcock, W. J., and Oliver, N. F., Ibid., 39, 57-8 (1949).
23 hlagrum, W., Windle, M.,and Jurmain, J. H., I b i d . , 39, KO.12 (1949). Manning, T . E., P h y s . Rev., 76, 173 (1949). Meggers, TI’. F., ASAL.CHEM.,21, 29-31 (1949). hleggers, W.F., Sci. X o n t h l y , 68, 3-11 (1949). Meggers, IT. F., and Scribner, E. F., J . Optical SOC.Am., iD press. hleggers, W. F., and Scribner, E. F., unpublished data. Minnaert. M. G. F., T r a n s . International Aetronomical U n i o n , 7 (1948) in press: D r a f t Reports, University Press, Cambridge, pp. 187-217 (1948). Moore, C. E.. “Atomic Energy Levels” Vol. I. Natl. Bur. Standards, Circ. 467, Washington, D. C., Goverment Printing Office. 1949. Moore, C. E.. “A Multiplet Table of Astrophysical Interest,” Contr. Princeton University Observatory, No. 20 (1945) ; Natl. Bur. Standards, Circ. 488 (Section 1, ,H-*aV, in press) Moore, F. L., Jr., unpublished data. Mosher, It. E.. Boyle, A. J., Bird, E. J., Jacobson, S . D., Batchelor, T. M., Iseri, L. T., and Myers, G. E., Am. J . Clin. Path., 19, 461-70 (1949). Murakawa, K., and Suwa, S., P h y s . Rev., 74, 1535 (1948). Oldfield, J. H., Spectrochim. A c t a , 3, 354-66 (1,948). Parks, T. D.. Johnson, H. O., and Lykken, L., A s . 4 ~ CHEM., . 20,822-5 ( 1948). Pearse, R. W .B., and Feast, M.W., Nature. 163. 686 (1949). PBrard, A., and Terrien, J., Compt. rend., 228, 964-7 (1949). Peter, H.. and Kreissig, G., 2. PfEanzenernahr., Diingung u. Bodenk., 42,41-4 (1948). Pritchard, L. R., P i t and Quarry, 41, 83-5 (1948). Riehm, H., 2 . anal. Chem., 128,249-64 (1948). Rozsa, J. T., J . Am. Ceram. SOC.,31, 280-3 (1948). Scribner, E. F., and Rleggers, W. F., “Index to the Literature on Spectrochemical Analysis, 1945-1950, Part 111,”to be published in 1951. Serfass, E. J . ,Levine, W.R., and Oliver, J. E., Platina. 35. 2603, 297 (1948). Shapiro, S.,and Hoagland. TI., Am. J . Phusiol., 153, 428-3) (1948). Shenstone, A. G., and Pittiuger. J. T., J . Optical SOC.Am., 39, 219-25 (1949). Short, H. G., and Dutton, W ,L., ANAL.CHEM.,20, 1073-6 (1948). Sihvonen, Y. T., Fry, D. L., Nusbaum, R. E., and Baumgartner, R. R., J . Optical S O C .Am., 39, 257-60 (1949). Sittner, IT. R., and Peck, E. R., Ibid., 39, 474 (1949). Skinner, If., and Lamb. W. E., B u l l . Am. P h y s . Soc.. 24, No. 1, 59 (1949). Smith, D. hl., and Wiggins, G. M . , A n a l y s t , 74, 95-101 (1949). Steinberg, R. H., and Belic, H. J., ASAL. CHmf., 21, 730 (1949) Suwa, S., P h y s . Rev., 76, 847 (1949). Thackeray, E. R., Ibid., 75, 1840-3 (1949). Timma, D. L., J. Optical SOC.Am., 39, 898-902 (1949). Tomkins, F. S., and Fred, M., Ibid.,39, 357-68 (1949). Toth, S.J., Prince, A . L., Wallace, A., and Mikkelsen, D. S.. Soil S c i . , 66, 459-66 (1948). T‘ancouleurs, .4.de, Compt. rend., 228, 1714-16 (1949). Voinar, A. O., and Rusanov, A. K., B i o k h i m y a , 14, 102-6 (1949). Weeks, D. W.,unpublished data. I
I
RECEIVEDNovember 23, 1949.
MASS SPECTROMETRY MARTIN SHEPHERD A N D JOHN A. HIPPLE, National Bureau of Standards, Washington 25, D. C.
D
URIKG the past year, mass spectrometry has advanced
partly in the interesting though somewhat confusing manoer characteristic of the emphatic but uncertain equestrian who mounted his horse and rode off in all directions at once. So we find, in various stages of discussion, planning, and construction huge spectrometers much greater than existing instruments, and little spectrometers much smaller than the present conventional size. The large spectrometers with crossed fields are intended for the measurement of fundamental constants, and a resolution of
about 25,000 was expected of one of them before its final completion w a s abandoned. The smaller ones, of the negative-ion or the magnetic-resonance types, may, in time, prove to be the poor man’s analytical mass spectrometer, for their resolution is good enough for many analytical applications. A continuous recording instrument of limited range has appeared. Analytical application, as well as instrument design, has branched out. I n development work, rather more effort has been devoted to the analysis of liquids or their heavy vapors than to
ANALYTICAL CHEMISTRY
24 gases. Furthermore, the simple gaseous mixtures have not attracted the attention accorded deuterated compounds and isotopes. Thus the field is becoming more interesting and also more diffuse. Before the diffusion has mixed everything too well, the American Society for Testing Materials, through its Committee D-3 on Gaseous Fuels, is standardizing procedures for the analysis of the simpler gaseous mixtures. ANA LYTlCA L APPLICATIONS
Hindin, Grosse, and Kirshenbaum have applied the “interndstandard” method to mass spectrometric analysis, and so opened a promising line of development (25, 34). I n conventional anal)-sis, the element sought is usually quantitatively converted to a specific compound of suitable properties, and this is isolated in pure form and quantitatively measured. I n the internal-standard method, the element sought is determined relative to another not originally present but added in known amount. For the spectrometric approach, if the sample is not gaseous, it is made to react to convert the element sought quantitatively to the gaseous state, in which the internal standard is present, and a portion of the product is withdrawn for analysis. The ratio of the unknown element to the known internal standard is constant and dipcloses the amount of the unknown. Thus no quantitative recovery of the reaction product is necessary. In this manner nitrogen has been easily determined in organic materials; and isotopic analysis for oxygen, carbon, and nitrogen in organic materials has been described. A considerable amount of work has been done in developing modifications of the inlet system and special techniques for the analysis of water, alcohols, and ovygenated compounds. There are some interesting reports in preparation, and three important papers have been published by Gifford, Rock, and Comaford (24), Langer and Fou (50), and Thomas and Seyfried (7’6). The greatest problem associated with analysis of this type was adsorption in the inlet system, which contributed gorgeous errors. Placing the leak virtually within the ionizing chamber and heating the system and trap, together ivith proper equilibration techniques, solved the difficult problem. Thomas and Seyfried also used an internal standard (CsHe), and reported the analysis of oxygenated compounds containing five or fewer carbons to *293 or better, water to 1%. Compounds analyzed included alcohols, aldehydes, esters, ethers, and acids. Gifford, Rock, and Comaford also reported the analysis of dilute aqueous solutions of oxygenated compounds. In addition to the two important developments discussed in the above two paragraphs, some difficult mixtures have tempted several workers. Honig (40) has reported the analytical technique used in the complicated analysis of hydrocarbons enriched
C
C
in CL3,including C‘.CCC, CC CC, C.CC, and CGC. Mohler and Dibeler ( 6 0 ) have discussed the mass spectrometric analysis of C2H2,C2D2,and C7,DE-I. Brinton and Blacet ( 1 1 ) have studied a mixture of deuterated aldehytirs. Mohler, Bloom, Lengel, and Rise have shown what can be done in the analysis of fluorocarhons with seven or fewer carbons (58). The analysis of gaseous hydrocarbons using 110th the mass and infrared spectrometers is described by Milsom, Jacoby, and Rescorla ( 5 7 ) . The method of calculation combines data from both spectrometers in a set of 2n equations in n variahlrs, solved by the reciprocal matrix method. The infrared spectrometer neatly assists the mass spectrometer in the determination of compounds with many isomers, APPLICATIOhS TO CHEMISTRY kND PHYSICS
Mass spectrometric procedures previously developed have been used for various purposes. Bailey and Van Meter ( 8 ) corrected the Dumas microanalysis by the mass spectrometer. Farmer and Brown (81) studied the deterioration of methane-filled Geiger-Muller counters. Robertson ( 6 8 ) used the mass spec-
trometer in studying the pyrolysis of methane, ethane, and n-butane on a platinum filament. Madorsky, Straus, Thompson, and Williamson (55) studied the pyrolysis of polyisobutene, etc., in like manner. Dibeler and Taylor ( 1 4 ) studied the deuterium exchange, isomerization, and hydrogenation of the n-butenes. Weller and Friedel ( 7 8 ) determined the isomer distribution in hydrocarbons from the Fischer-Tropsch process. Kistemaker (43) has reviewed some of the chemical applications of the mass spectrometer. Probably the outstanding event this year in the measurement of packing fractions was the announcement of the results of Roberts and Nier ( 6 7 ) obtained with the electrometric method. These results indicate a precision comparable with the best yet attained by the photographic method. The Roberts-Xier method was reported in last year’s review (37). Duckworth (1719) and co-workers have a modified Dempster-type instrument in operation and have reported new measurements. Ogata ( 6 2 )has measured the isotopic weights of some of the elements of medium weight. This general field has been an active one, with the Chicago group taking a leading role ( 1 , 16, 20, 26, 67,29-32, 36, 44, 46, 51, 53, 54, 61, 64, 78, 7 5 ) . Dempster and Shaw ( 1 2 ) have made an interesting observation on the relative retardation of high speed ions by the residual gas and have shown significant resulting differences in the pairings of doublets. MASS SPECTRA
The American Petroleum Institute Research Project 44, conducted a t the National Bureau of Standards, Washington, D. C., has accumulated 436 mass spectra of various gases and vapors, including paraffins, alkyl cyclopropanes, alkyl cyclobutanes, alkyl cyclopentanes, alkyl cyclohexanes, mono-olefins, diolefins, alkyl cyclo-olefins, acetylenes, diacetylenes, alkyl benzenes, and miscellaneous hydrocarbons. Various spectra have been reported: pentaborane by Dibeler, Mohler, IT’illiamson, and Reese ( 1 3 ) ; hydrogen deuteride by Friedel and Sharkey ( 2 2 ) ; octanes by Bloom, Mohler, Lengel, and Wise ( 6 ) ; various organic compounds by Roberts and Johnson ( 6 6 ) ; hydrogen and deuterium by Bauer and Beach ( 3 ) . Mohler, Bloom, Wells, Lengel, and Wise (59) discussed the doubly charged ion spectra in the mass spectra of hydrocarbons. Bloom, Mohler, IT’ise, and Wells ( 7 ) have compiled the metastable transition peaks in the mass spectra of about 170 hydrocarbons. The effect of temperature on mass spectra has been studied by Stevenson ( 7 4 ) . INSTRUMENTATION
Mariner and Bleakney ( 5 6 ) have described their large mass spectrometer employing crossed electric and magnetic fields. A resolution of 1 in 25,000 was expected from this instrument. Another such spectrometer is planned and in construction. Bennett ( 4 ) has described a radio-frequency instrument which may be developed into a good analytical spectrometer. I t is small, sensitive, and relatively inexpensive, and may some day be the poor man’s mass spectrometer, Hipple, Sommer, and Thomas (58)reported a magnetic resonance method of ion analysis. Their instrument attained a resolution of 1 in 3500. The device employed no slits, and its high sensitivity and readily variable resolution suggest that it may be useful for gas analysis as well as precise mass measurements. It, too, is small and relatively inexpensive. A mass spectrometer for continuous gas analysis has been developed by Hunter, Stacy, and Hitchcock (41). It is designed for respiratory studies, with three exit slits, for nitrogen, carbon dioxide, and oxygen. The time of response is fast, permitting determinations every 0.2 second. Progress has been made in precision instruments for the measurement of packing fractions. Richards, Hays, and Goudsmit (66) constructed an instrument based on principles previously reported, An accuracy of 1 in 10s near mass 100 was attained.
V O L U M E 2 2 , N O . 1, J A N U A R Y 1 9 5 0 An isotope ratio mass spectrometer of the Nier type has been made commercially by the Consolidated Engineering Corporation. Similar instruments are described by Paul (63) and by Lewis and Hayden (52). General analytical and isotope ratio mass spectrometers have now been made commercially in England by Metropolitan Vickers, and in France by the Compagnie GBnerhle de TBlBgraphie Sans Fils. A leak-detector mass spectrometer utilizing a cold cathode ion source has been developed by Thomas, Sommer, and Wall ( 7 7 ) . Hipple and Thomas have reported a time-of-flight instrument (39). A metal mass-spectrometer tube with guarded gold gasket has been described by Hickam ( 3 3 ) . Roth ends are conveniently removable, which is rather nice. Bernas and Nier ( 5 ) have described the production of an intense ion beam, and Winn and Nier (79) have developed an excellent emission regulator. Dibeler and Taylor (15) have described glass diaphragm leaks. Theoretical studies of improved focusing have continued (23, 35, 47, 48,69, 7 0 ) . The production of ions has received some attention (28, 45, 7 3 ) . REVIEWS
Several reviews of the subject have been published, including those by Hutter ( 4 2 ) , Inghram ( 4 3 ) , Roth ( 7 l ) , Boivin (8-10), Thode (Y6),and Kistemaker (49). LITERATURE CITED
Aldrich, L. T., and Nier, A. O., P h y s . Rea., 74, 1590 (1948). Bailey, C. W.,and T’an Meter, R., Petroleum and Oil-Shale Experiment Station, Bureau of Mines, Laramie, Wyo., Consolidated Group R e p t . 65 (1949). Bauer, N.. and Beach, J. Y., J . Chem. P h y s . , 17, 100 (1949). Bennett, Vi. H., J . Applzed Phys., in press. Bernas, R. H., and Kier, -1. O., Rev. Sci. Instruments, 19, 895 (1948). Bloom, E. G., Mohler, F. L., Lengel, J. H., and TTise, C. E., J . Research ‘Vatl. B u r . Standards, 41, 129 (1948); R P 1912. Bloom, E. G., hfohler, F. L., Vise, C. E., and Wells, E. J., J . Reseamh S a t l . Bur. Standards, 43, 65 (1949). Boivin, Marcel, C h i m . u m Z . , 31, 35 (1949). Ibid., p. 61. Ibid., p. 80. Brinton, R. I
