Mass Spectral Analysis of Chloropicrin under Negative ion Chemical ionization Conditions

摘要

A chemical ionization (CI) method is developed for the first time to obtain molecular weight information forchloropicrin (CP), which is used as a chemical warfare agent and as an insecticide. The study includes a detailedinvestigation on the behavior of CP under electron impact (EI) and CI. Reagent gases of different nature, i.e.,methane, isobutane, ammonia, hydrogen, and carbon dioxide, were used for CI analysis. Negative ion mode isfound more sensitive than positive ion mode for the EI/CI mass spectrometric analysis of CP, but none of themethods provided molecular weight information, except negative ion CI using ammonia as the reagent gas (NICI(NH_3)). The NICI (NH_3) showed formation of the quasimolecular ion, [M + H]~-, in addition to other adduct ions.The [M + H]~- abundance critically depends on the source t6mperature, reagent gas pressure, and concentration ofthe analyte, and it can be 13percent under optimized conditions by which CP can be confirmed unambiguously. Thismethod meets the criteria used in official proficiency tests conducted by OPCW for confirming the molecular weightof the unknowns.