Determination of enantiomeric purity of commercial 14C- and 3H-labeled L-α-amino acids

LeFevre, Joseph W.; Bonzagni, Neil J.; Chappell, Lara L.; Clement, David J.; Albro, Jeb R.; Lezynski, Denise M.

doi:10.1002/(sici)1099-1344(199806)41:6<477::aid-jlcr104>3.0.co;2-3

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…The best separations using 1 × 3′′ reversedphase plates 12 occur with valine, leucine, and isoleucine, all of which contain bulky aliphatic side chains. Enantiomeric purity analyses of other radioactive amino acids using 5 × 20-cm reversed-phase plates and various solvents have recently been reported (22).…”

Section: Discussionmentioning

confidence: 99%

Determination of the Enantiomeric Purity of Commercial L-[U-14C] Valine: An Experiment Utilizing Reversed-Phase Thin-Layer Chromatography and Liquid Scintillation Counting

LeFevre

1998

J. Chem. Educ.

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A survey of this Journal shows that only a few experiments involving radioactive organic compounds have been published in the last 30 years (1-9). References 10 and 11 cite numerous experiments utilizing radioactive inorganic elements. The experiment described here analyzes a commercial uniformly carbon-14 labeled L-valine sample (L-[U-14 C]Val) for its enantiomeric purity. This type of information is crucial to researchers who require enantiomerically pure radioactive amino acids for investigating stereochemical aspects of biosynthetic pathways (12,13).The experiment utilizes a reverse-isotope dilution technique that was performed on the microscale level in three threehour periods by pairs of students in an advanced chemistry laboratory at SUNY Oswego. The experiment involves the following steps:1. Diluting 0.5-1 µCi of L-[U-14 C]Val with nonradioactive racemic DL-valine, 1 followed by conversion to the highly fluorescent 5-dimethylamino-1-naphthalenesulfonyl (dansyl, DNS) derivatives using DNS-chloride (14). 2. Resolving the enantiomeric DNS-DL-Val by reversedphase thin-layer chromatography (TLC) via diastereomeric inclusion complexes with β-cyclodextrin (β-CD) as a mobile-phase additive (15, 16). 3. Scraping the pure DNS-D-and -L-Val from the plate and subjecting each sample to liquid scintillation counting (LSC) to determine the relative amounts of radioactivity present in each.

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Section: Discussionmentioning

confidence: 99%