Determination of Lanthionine and Lysinoalanine as N-Trifluoroacetyl n-Butyl Esters by Gas-Liquid Chromatography

Abstract

A gas-liquid chromatographic method was explored for the analysis of lanthionine and lysinoalanine as well as lysine, cystine, and S-carboxyethylcysteine in chemically modified wool samples. The amino acids in the wool hydrolyzate were converted to n-butyl esters of N-trifluoroacetyl derivatives according to the method of Gehrke et al. The retention indices of the five amino acids mentioned above as well as other protein amino acids such as proline, phenytalanine, histidine (as mono and diacyl derivatives), tyrosine, arginine, and tryptophane were determined on OV-17 and Dexsil 300 GC. It was found that Dexsil 300 GC was suitable for the intended analysis with n-butyl stearate as an internal standard. The molar responses of these amino acids were determined.