V O L U M E 23, NO. 1, J A N U A R Y 1951
207 graphic photometry. -4lthough the zones have tieen measured directly by counting radiation or by excising portions of the chromatogram and performing a radio-assay, there is considerable adbantage in direct scanning and recording.
Use of Beta-Rav Densitometrv in Paper Chromatography study of the absorption and scattering of betaIlemsSraysAof detailed with the intent to study their applicability to the probpaper chromatography, a recording system was set up consisting of a methane-type ionization chamber and a pulseintegrating counter driving- :t Brown recorder. These SAMPLE w i c ~uscd with a narrowly collimated SrgO source of betu-rays. This work is still in progress, but in the ORIGIN intrrim a related problem in chromatography arose, for which most of the components were immediately .Quited. The immediate purposv of this coinmunicat,ion is to tlc'wribe a simple application of part of this equipment t o the rapid analysis of labeled chrom:itoyrams. For some time it has bwn customary to detect, colorh*ss chromatographic zones by placing tthe finished cliromatogram in contact with photographic film ( 1 ) . Then, wherever a zone contains a radioactive tracer such its I 1 3 I , Cl', or S l 5 , a developable image will result. This has been a po\v-erful tool in nunitrous investigations by extcriding the techniques, not only of traccr analysis, Iut, of paper -k chroniatography. Minor defects in the method : t i t s the very long exposures which are often required, and the fact that :t quantitative estimate of film blackeniiig in such cases involve? nearly dl the uncertainties of photo-
RECORDER PEN\
CHART
PAPER
CHROMATOGRAM
/
A
b/
PAPER
IONIZATION CHAMBER
CHROMATOGRAM
B
Figure 1
COUNTERWEIGHT
T o illustrate this technique, a paper strip chromatogram, in which the separated zones or bands contained C14 labeled organic compounds, was suspended from a nylon thread as shown in Figure 1,A. A small weight was fastened a t the lower edge of the paper strip and the nylon thread was passed over two small pulleys, beyond which it was fastened to the recorder chart with a patch of Scotch tape. This simple, but temporary expedient permitted the chromatogram to be drawn across a fine lead slit in front of the ionization chamber at a uniform rate and in exact conformity to chart motion. A block of lead was placed behind the sample to enhance the geometry of the system by virtue of the back-scattering effect, RADIO-AUTOGRAPH
I5 DAY EXPOSURE
BACKGROUND
18 MINUTES
Figure 2 .\ typical record is shown in Figurc 2,A. The five peaks, .4, H, C, D, and E, starting at thc sample origin, A , represent, the
counting of C14 beta-particles as a function of elapsed scanning time and, by virtue of the scanning mechanism, of exact linral displacement along the chromatogrtiin. The base line of reference is the average background rate which was 70 counts per minutc'. At' the greatest excursion, the counting rate was not greater t'han 200 counts per minute. The integrating circuit n-as provided with a time constant of 7 . 5 seconds. Above the record in Figure 2 9 , is a sketch of the radio-autograph produced on x-ray film for this particular chromatogram after a 15-day exposure. This sketch is an accurate tracing from the film, with respect to lineal displacements, hut obviously not in density. The striking advantage lies in the amount of information obtained i n 18 minutes as compared with a Id-thy exposure to film. Mere photonietry of the film would invitcx a great number of errors. In this connection, the small peak :it R was highly reproducible, nhercas on the film it was difficult to decide whether there was any pcrceptihle blackening or not. I t is not our purpose to discuss thcl nature of the results rcpresented by this chromatogram. I t rcsprrsents metabolic products rcsulting from the administration of C" labeled compounds and is being presented elsewhere in drtail by Roth arid associates. A typical study of this nature has b c v n published ( 3 ) . The technique herein suggested tvould set'ni to afford increased precision and a trcmendous saving of timc; i n the instance illustrated here, by :i factor of 1200-fold. Although the simple string-drivcs scanning system is inore than accurate eriuuyh, xve have reconmiended w more robust scanner as shown schematically in Figure 1,H. Similar scanners for photometry in t,he visible and ultraviolrxt light havc bcen uwd and dcscribed in previous work ( 2 ) . Whcrever a sufficient volume o f work of this nature is done, an :tdditional and rather obvious instrumental extension would be Jvarficntcd This would consist of :in d j u s t a b l e limit switch at-
ANALYTICAL CHEMISTRY
208 tached to the rrcordrr servo-syskm, a stepping relay, and a bank of magnetic counters. The limit switch would be set to close whenever the counting exceeded the average background rate by a stated amount-say, 5%. This switch would transfer the amplified pulses t o one of the magnetic counters as well as to the integrating circuit which drives the recorder. The counter would record the total number of pulses over the entire coiitour of it single zone. After the switch was de-energized, the stepping relay would transfer to a second magnetic counter, which would then be ready to count pulses for the next zone. In this manner, a bank of counters would indicate the integrated values of concentration in each zone. It is likely that the completely recorded curve would still be of interest, inasmuch as it affordb an accurate means of calculating RF values, and a general view of the chromatographic pattern.
0 5 c i a l Methods of Analysis of the Association of Official Agricultural Chemists. H . A . Lepper, chairman. 7th ed. xv 910 pages. Association of Official Agricultural Chemists. P.O. Box 540, Benjamin Franklin Station, Washington 4, D. C. $10 domestic, $10.50 foreign.
ACKNOW LEDGJI ENT
The Fourth .1111111~1 Symposium on Analytical Chemistry will be held a t Louisiana State University, Baton Rouge, La., from January 29 to February 1. N. Howell Furman, President of the h E R I c a s CHEmcAL SOCIETY,will be the speaker a t the banquet. A feature of the symposium will be the attendance of a number of graduate students h m various universities, who will be housed a t nominal cost in university dormitories. There will also be exhibits of instruments, and an inspection of the new addition to the Chemietry Building of Louisiana State University. Hotel arrangements should be made directly with the Hotel Heidelberg, Baton Rouge, La. On February 1 a round-table discussion of problems in the teaching of analytical chemistry is scheduled, which will include the following panel members: Martin, Burkhalter, de Vrieu, Ayres, Elving, Kenner, Vick, LeRosen, West, Rogers, Fischer, hlerritt, and Furman. The following papers a i l 1 be presented in the symposium
We are indebted to 1,. J. Roth for the chromatogram and for details of his forthcoming publication; to J. R. Liljenthal, Howard Eberline, and staff for design and construction of pulse-integrating counter and associated equipment; and t o E. R. Jette for sustained interest and encouragement in these investigationH. LITERATURE CITED
(1) Clegg, D.L., Ax.4~.CHEM., 22,48 (1950). (2) Miiller, R.H., Ibid., 22,72 (1950).
(3) Roth, L. J., Leifer, E., Hogness, J. R., and Langham, \V. I f . . J. B i d . Chem., 178,963 (1949).
RALPHH. hIU1.LER .Vew York Universitil ,Vew York, ,V. Y.
EDWARD K.W I ~ E
University of Kansas Lawrence, K a n .
RECEIVED October 20, 1950 Work done under the auspices of the Atomic Energy Commission, a t the Lob Alamos Scientific Laboratory, LOBhlanios. N. 11
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Fourth Symposium on Analytical Chemistry
PHILIP J. ELVISG. Polarography of Organic Compound* PAULDELAHAY.Oscillographic Polarography
Determination of Uranium and Thorium The U. S. Atomic Energy Commission has published li neu technical booklet describing the analytical procedures for determining the uranium and thorium contents of ores. The booklet wa8 prepared by the technical staff of the A.E.C.’s Analytical Laboratory a t Xew Brunswick, 1;.J., under the direction of the Raw Materials Operations Office. It is available from the Supcrintendent of Documents, U. Government Printing Office, Washington 25, D. C., for 20 cents per copy. The manual contains a compilation of the methods for the analysis of pitchblende, carnotite-bearing sandstone, shales, phosphate rock, and monazite sands. It was prepared for the purpose of assisting and encouraging commercial laboratories, as part of their normal business, to take over gradually the function of making uranium analyses for prospectors and miners, a function now largely performed by the Atomic Energy Commission, the U. S. Geological Survey, and the Bureau of Nines.
s.
N E W BOOKS A.S.T.M. Standards on Textile Materials (with related informa572 pages. American Society for Testing Matetion). Xii rials, 1916 Race St., Philadelphia 3, Pa. $4.50. Anal-$cal Chemistry of the Manhattan Project. C . J. Rodden, editor-in-chief. xx 748 pages. McGraw-Hill Rook Co., 330 West 42nd St., New York 18, N.Y. $6.75.
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GILBERT AYRES. Colorimetry W. H. BENNETT. Mass Spectrometry G. L. ROYER. Microscopy OLENXANCG.High Frequency Oscillators A. BENEDETTI-PICHLER.Microchemical Technique. R. B. BARYES. Infrared Spectrometry L. B. ROGERS. Electrolysis a t Controlled Potential ROBERT FISCHER. Electron hlicroscopy LYhnx MERRITT. Organic Reagents
Pittsburgh Conference on Analytical Chemistry S . II. Furinan, Princeton University, President-Elect of tht= .imRIcAN CHEMICAL SOCIETY,will deliver one of the keynote addresses a t the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, to be held in the William Pelin Hotel, Pittsburgh, Pa., March 5 t o 7 . Other speakers will be XI. G. hlellon, Purdue University, who will discuss “Automatic Operations in Analysis,” and G. €3. Dieke, Johns Hopkins University, who will speak on “Fundamental Considerations to Be Employed hy the Practicing Spectroscopist.”
Fourth Symposium on Analytical Chemistry. Louisiana State University, Baton Rouge, La., January 29 to February 1, 1951 Chemical Institute of Canada, Division of Analytical Chemistry. Mount Royal Hotel, Montreal, Canada, February 16 and 16, 1951. Third annual regional conference Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. William Penn Hotel, Pittsburgh, Pa., March 5 to 7, 1951 Fourth Annual Summer Symposium. Waahington, D. C.. June 14 to 16, 1951
