Computational and experimental studies of chemical ionization mass spectrometric detection techniques for atmospherically relevant peroxides

Abstract

We report the results of computational and experimental studies concerning the chemical ionization mass spectrometric detection of hydrogen peroxide (HOOH) and methyl hydroperoxide (CH 3OOH). GAUSSIAN2 (G2) electronic structure calculations are used to predict structures, natural charges of the atoms and energies for the neutral species, as well as for the cation, anion, and the proton and fluoride adduct species. These calculations are used to predict ion–molecule reaction thermodynamics as a guide to the experimental development of chemical ionization mass spectrometric detection methods. Both HOOH and CH 3OOH are predicted to react exothermically with O 2 + and F − to yield the cationic and fluoride adduct species, respectively. In addition, CH 3OOH is predicted to react exothermically with H 3O + to yield the proton adduct species. The feasibility of F − chemical ionization mass spectrometric detection of peroxides was experimentally explored through kinetic studies. The fluoride adduct formation reactions for both HOOH and CH 3OOH were found to proceed at or near collision-limited rates.