VERIFICATION OF NONPRODUCTION OF CHEMICAL WARFARE AGENTS .2. LARGE VOLUME INJECTIONS IN MICROCOLUMN LIQUID-CHROMATOGRAPHY USING FLAME PHOTOMETRIC DETECTION

The sensitivity and separation performance of microcolumn liquid chromatography coupled with a flame photometric detector were considerably improved by the direct injection of large sample volumes (approximately 10 muL) and by peak compression. Extremely narrow peaks can be obtained by adding displacers such as hydrochloric acid (ion-exchange mode) or n-butanol (reversed-phase mode) to the sample. The system was used for the determination of ethyl methylphosphonic acid, isopropyl methylphosphonic acid, and pinacolyl methylphosphonic acid which are the hydrolysis products of the super-lethal nerve agents VX, sarin, and soman, respectively, and of the final degradation product, methylphosphonic acid. The detection limits for the alkyl methylphosphonic acids and sarin in water were 1-20 ppb. Two examples were used to demonstrate the practicality of the present procedure. Sarin and the much more polar isopropyl methylphosphonic acid were simultaneously determined in a spiked surface water sample used for verification studies. Low-ppb levels of phosphorous acid were identified in mustard gas.