Ion Chemistry of VX Surrogates and Ion Energetics Properties of VX: New Suggestions for VX Chemical Ionization Mass Spectrometry Detection

摘要

Room temperature rate constants and product ion branch-ning ratios have been measured for the reactions of numer-nous positive and negative ions with VX chemical warfarenagent surrogates representing the amine (triethylamine)nand organophosphonate (diethyl methythiomethylphos-nphonate (DEMTMP)) portions of VX. The measurementsnhave been supplemented by theoretical calculations of thenproton affinity, fluoride affinity, and ionization potentialnof VX and the simulants. The results show that manynproton transfer reactions are rapid and that the protonnaffinity of VX is near the top of the scale. Many protonntransfer agents should detect VX selectively and sensitivelynin chemical ionization mass spectrometers. Charge trans-nfer with NO should also be sensitive and selectivensince the ionization potential of VX is small. Thensurrogate studies confirm these trends. Limits ofndetection for commercial and research grade CIMSninstruments are estimated at 80 pptv and 5 ppqv,nrespectively.