Analysis of degradation products of organophosphorus chemical warfare agents and related compounds by liquid chromatography mass spectrometry using electrospray and atmospheric pressure chemical ionisation

A qualitative screening procedure was developed for the detection and identification of phosphonic acid hydrolysis products of organophosphorus chemical warfare agents, using liquid chromatography-mass spectrometry with electrospray ionisation (LC-ESP-MS). A mixed C-8,/C-18,, reversed-phase column with gradient elution gave good chromatography for a series of phosphonic acids. Detection limits for aqueous solutions of standards were <50 ng/ml (<0.25 ng injected), providing an increase in sensitivity up to an order of magnitude compared with LC-MS using atmospheric pressure chemical ionisation (LC-APCI-MS). The methodology provides a rapid screening procedure for the hydrolysis products of nerve agents in aqueous samples and extracts. The application of LC-ESP/APCI-MS and LC-ESP/APCI-MS-MS to the identification of dialkyl esters of phosphonic acids is also described. Examples are given of the application of LC-MS to spiked water samples analysed during the course of proficiency testing. (C) 1998 Elsevier Science B.V.