A SIFT Study of Reactions of Positive and Negative Ions With Polyfluoroalkyl (PFAS) Molecules in Dry and Humid Nitrogen at 393 K.

Rationale: Data are required for SIFT-MS analysis of perfluoroalkyl and polyfluoroalkyl substances (PFAS), which are persistent in the environment and cause adverse health effects. Specifically, the rate coefficients and product ion branching ratios of the reactions of HO, NO, O •, O•, OH, O •, NO and NO with PFAS vapours are needed.

Methods: The dual polarity SIFT-MS instrument (Voice200) was used to generate these eight reagent ions and inject them into the flow tube with N carrier gas at a temperature of 393 K.

Kinetics of reactions of NH with some biogenic organic molecules and monoterpenes in helium and nitrogen carrier gases: A potential reagent ion for selected ion flow tube mass spectrometry.

Rationale: To assess the suitability of NH as a reagent ion for trace gas analysis by selected ion flow tube mass spectrometry, SIFT-MS, its ion chemistry must be understood. Thus, rate coefficients and product ions for its reactions with typical biogenic molecules and monoterpenes need to be experimentally determined in both helium, He, and nitrogen, N , carrier gases.

Methods: NH and H O were generated in a microwave gas discharge through an NH and H O vapour mixture and, after m/z selection, injected into He and N carrier gas.