Mass spectrometry peroxy radicals

Another approach combines the mass spectrometric derivatization approach with chemical amplification (Reiner et al., 1997, 1998). In this instrument, H02 and R02 are converted to OH through the reactions in the chemical amplifier approach discussed below, and the OH is then converted to H2S04 by reaction with S02 and measured by chemical ionization mass spectrometry using NO, (HN03) clusters as described earlier. In this case, the use of isotopically labeled S02 is not necessary, since the ambient H2S04 concentration is much smaller than that of the peroxy radicals. 

Reiner, T., M. Hanke, and F. Arnold, Atmospheric Peroxy Radical Measurements by Ion Molecule Reaction-Mass Spectrometry A Novel Analytical Method Using Amplifying Chemical Conversion to Sulfuric Acid, J. Geophys. Res., 102, 1311-1326 (1997). 

Kinetic studies have been performed on the individual steps occurring in the NO3 and OH initiated oxidation of VOCs. The studied reactions include essentially reactions of NO3 with alkenes, di-alkenes and dimethyl sulfide (DMS), reactions of NO3 with intermediate peroxy radicals (HO2, CH3O2, C2H5O2) and reactions of OH with methane and oxygenated VOCs (ethers, alcohols). The rate constants for these reactions have been measured, and mechanistic information has been determined. The experimental methods used were discharge-flow reactors coupled with mass spectrometry, electron paramagnetic resonance (EPR), laser-induced fluorescence (LIF) analysis and the laser photolysis associated with LIF analysis. The discharge-flow LIF and laser photolysis LIF experiments have been especially developed for these studies. 

Hanson D, Orlando J, Noziere B, Kosciuch E. Proton transfer mass spectrometry studies of peroxy radicals. Int J Mass Spectrom. 2004 239 147-59. 

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