Atmospheric pressure chemical ionization-mass spectrometry and capillary electrophoresis for the analysis of chemical warfare agent degradation products

The use of the cationic surfactant, didodecyldimethylammonium hydroxide (DDAOH), to enable the reversal of electroosmotic flow (EOF) was the key strategy in the development of rapid and sensitive capillary electrophoresis (CE) analysis methods for the determination of nerve agent degradation products in aqueous matrixes. The target analytes, alkylphosphonic acids and their half-esters, are anionic degradation products of phosphonate ester-type nerve agents (e.g. Soman and Sarin) and are detected by indirect UV or conductivity. The CE separation uses coelectroosmotic conditions (the direction of the EOF and the electrophoretic mobility of the anionic analytes are both towards detection at the anode end), giving excellent separation in less than 3 minutes. The use of DDAOH for EOF reversal provided better performance than the more commonly used cetyltrimethlyammonium hydroxide. The methods were evaluated on environmental samples. Recovery and linearity were evaluated and analyte identities for blind test samples were confirmed by mass spectrometry.