MICROCOLUMN LIQUID-CHROMATOGRAPHY WITH THERMIONIC DETECTION OF THE ENANTIOMERS OF O-ETHYL S-2-DIISOPROPYLAMINOETHYL METHYLPHOSPHONOTHIOATE (VX)

An improved interface for the on-line coupling of microcolumn liquid c hromatography (micro-LC) with thermionic detection (TID) is described. Modifications have been made to enable separate adjustment of the elu ent introduction and the detector flame temperature in order to improv e the sensitivity and ease of use of the system. The micro-LC-TID was used for the chiral separation of the nerve agent O-ethyl S-2-diisopro pylaminoethyl methylphosphonothioate (VX). Baseline separation for the enantiomers of VX was obtained on Chiralcel on using 1% isopropanol i n hexane as the eluent. The detection limit of VX using 60 nl injectio ns is ca. 5 mu g/ml (ppm range). However, when using large-volume inje ctions (10 mu l) the detection limit is ca. 25 ng/ml (ppb range).