High Performance Liquid Chromatographic Analysis for Free Valine in Plasma

Abstract

A precolumn derivatization method is presented with the use of a fluorescent derivative, 1-dimethylaminonaphhalene-5-sulfonyl-chloride, dansyl chloride, for the detection of free valine in plasma. Dansylated amino acids were determined in deproteinized samples by reverse-phase liquid chromatography. The level of detection is 100 femtoraoles (10^?15). Sample preparation required precipitation of proteins with trichoroacetic acid and removing the excess acid with water saturated ether. The deproteinized sample was adjusted to pH 9.0 and reacted with dansyl chloride. The dansylated products were detected by ultraviolet and fluorescence spectrometry. Elution time for valine subsequent to injection is 25 minutes, while the total assay requires less than 50 minutes.