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S.,Powell, H., .llature 173, 1143 (1954). 12’1 Hoffman. Allen J.. Ludwig. B. J.. (1) Curry, A.
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(5) Parker, Kenneth D., Kirk, Paul L., ANAL.CHEM.33, 1378 (1961). ( 6 j Rajesivaran, Ponnusamy, Kirk, Paul L., (Part 1). Bull. Narcotics, U . S., Dept. Social Aflairs XIII, KO. 3, 15-37 (1961). (7) Ibid.. Part 2 . in mess. (8) Ryan, James A,, J . Smer. Pharm. Assoc., Sci. Ed. 48, 241 (1959). (9) Stewart, C. P., Stolman, A., “Toxicology,” Vol. 2, pp. 549, 551, Academic Press, Xew York, 1961. (10) Walkenstein, ’ Sidney S., Knehel,
Cornelius ll., IIacmullen, Joyce A.. Seifter, Joseph, J . Pharmacol. E.rptl. Therap. 123,254 (1958). RECEIVED for review Xoveinber 27, 1961. Accepted March 2 , 1962. n’ork supported by grants from the rational Institutes of Health, U. S.Public Health Service (RG-4372 and RG-5802 I , and from the Research Committee, L-niversity of California. Reported at the Fall Meeting of the California .%ssociation of Criminxlists, San Francisco, Octolwr 1961.
Analysis of Zone Spreading in Paper Chromatography by a Detection Limit Method KANA1 LAL MALLIK and J. CALVIN GlDDlNGS Department o f Chemisfry, University o f Utah, Salt Lake City, Utah
F An experimental method i s proposed for determining the basic plate height parameters of paper chromatography in terms of the apparent spot length. This method corresponds with the usual operation of paper chromatography where zones are detected and evaluated by visual means. The theory relating the experimental observables and the basic molecular parameters is developed and applied to six chromatographic systems. The results are interpreted in terms of diffusion and adsorption phenomena within the paper. migration of a chromatographic zone is characterized a t the molecfilar level by a number of random proc’sses ( 3 ) . Foremost among these is ’he sorption-desorption process which makes the don nstream motion of solute molecules intermittent in nature. An important consequence of this random motion, aside from the influence on the Fate of zone migration, is the spreading ,f the zone in the flow direction. This cau‘es the overlap of neighboring zones. anti thus has a direct bearing on the rfficiencv of chromatographic ieparatiorl‘hesp factors have received a v a t ( 1 ~ cri ~ 1 evperimental and throreti~ $ Pttcrition 1 in so far as gas chromatogr;rahg is wncerned, but little effort hren applied to correlate zone struc+ ~ ~with r p the niolecular processes occur1 ~ g in pRper chromatography. The i rTh in evperiinental evidence stems, r i l r t , :wm the conventional technique foi detecting zones in paper chroylatograuhy, i.. , a visual technique employing natural or induced light abi r 2 r h g p r o p d i e s of the solute zones. quch 5 tecnnique is incapable of yielding ietaiied x a e structure, although it is po-sitile ro
