Separation of chemical warfare agent degradation products by the reversal of electroosmotic flow in capillary electrophoresis

We report the development of analyses for nerve agent degradation products or related species by the reversal of electroosmotic now in capillary electrophoresis (CE), The developed methods were used in this laboratory for analysis of samples in the second and third official proficiency tests (International Round-Robins) for the Provisional Technical Secretariat/Preparatory Commission for the Organization for the Prohibition of Chemical Weapons, and those results are reported here, Analytes studied include methylphosphonic acid (a dibasic acid), the monoisopropyl ester of ethylphosphonic acid, and the monoalkyl esters of methylphosphonic acid (R = ethyl, isopropyl, isobutyl, pinacolyl (3,3-dimethyl-2-butyl), cyclohexyl, and 2-ethylhexyl). The cationic surfactants used here for the reversal of electroosmotic now are didodecyldimethylammonium hydroxide and cetyltrimethylammonium hydroxide, CE methods using conductivity or indirect UV detection provide a good separation efficiency and very high sensitivity for the analysis of such compounds, The detection limits for these species were about 75 mu g/L when using conductivity detection and about 100 mu g/L when using indirect UV detection, Because pH plays an important role in the CE separation of the alkylphosphonic acids and their monoesters, the influence of pH on these separation systems was investigated, Electrolytes were stable for at least 3 months, Excellent separation efficiency and freedom from interference due to common anions were obtained in the developed methods which typically achieved complete separations in less than 3 min, The method was applied to aqueous leachates of soil, wipes of surfaces, and vegetation sampled from a held site known to have been exposed to nerve agents and subsequently cleaned up, The data from these environmental samples indicated that the method can be expected to be useful for environmental monitoring.