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  Home > JCE Print > Journal of Chemical Education > Issues > 1998  > October  >
In the Laboratory
Determination of the Enantiomeric Purity of Commercial L-[U-14C] Valine: An Experiment Utilizing Reversed-Phase Thin-Layer Chromatography and Liquid Scintillation Counting
Joseph W. LeFevre
Chemistry Department, State University of New York (SUNY) College at Oswego, Oswego, NY 13126
Cover
October 1998
Vol. 75 No. 10
p. 1287
Abstract
The enantiomeric purity of commercial L-[U-14C]valine was determined. The process involved sequential dilution with nonradioactive DL-valine, N-dansylation using dansyl chloride, and resolution using reversed-phase thin-layer chromatography in the presence of b-cyclodextrin, a chiral mobile phase additive. Liquid scintillation counting of the bands corresponding to DNS-D- and L-valine gave the enantiomeric purity, as well as the percent radiochemical yield. Because the derivatization reaction proceeded without racemization, the results corresponded to the relative amounts of radioactive D- and L-valine in the commercial sample. The analyses were easily performed using less than 1 µCi of L-[U-14C]valine per pair of students. This laboratory experiment provides students with valuable experience in handling radioisotopes, illustrates the use of liquid scintillation counting as a sensitive detection method, reinforces important stereochemical relationships, and can be applied to the analysis of other radioactive amino acids.
More Information
*  Citation
 LeFevre, Joseph W. . J. Chem. Educ. 1998 75 1287.
*  Keywords
 chromatography, isotopes, microscale, nuclear, radiochem, stereochem, amino acids, laboratory instruction
*  History
 Created:
Last Updated:		 June 21, 1999
June 24, 2005
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