title: Evaluation of D-amino acid levels in human urine and in commercial L-amino acid samples.
abstract: Detectable levels of four free D-amino acids (phenylalanine, tyrosine, tryptophan and leucine) were found in human urine. This was accomplished using a liquid chromatographic coupled column (i.e., achiral-chiral) method that was developed for the rapid and sensitive analysis of these compounds. The technique was tested on a series of commercial L-amino acids. Care was taken to minimize racemization. Trace to percent levels of contaminating D-enantiomers were found in all commercial samples. In urine the D-amino acids ranged from several hundredths of a percent up to percent levels of the corresponding excreted natural L-amino acids. There were no apparent correlations between the amount of amino acids excreted and the relative amount of D-enantiomers present. Currently this study is being expanded to include additional amino acids and a variety of other physiological fluids.
authors.affiliation: Department of Chemistry, University of Missouri-Rolla, 65401, Rolla, MO, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Armstrong
authors.forename: J D
authors.initials: JD
authors.lastname: Duncan
authors.forename: S H
authors.initials: SH
authors.lastname: Lee