Evaluating the Utility of an Atmospheric Pressure Chemical Ionization Mass Spectrometer for Detecting Organic Peroxides During Beta-Pinene Ozonolysis Experiments

The intent of this study was to use a positive-ion atmospheric pressure chemical ionization mass spectrometer ((+) APCI-MS/MS) to detect organic peroxide products formed during β-pinene ozonolysis experiments. Detection was based on utilizing the neutral-loss scan (NLS) analysis mode of the APCI-MS/MS to observe ion signals exhibiting unique mass losses of 34 u. This mass loss was considered exclusive to protonated organic peroxides containing a hydroperoxy moiety. Given this observation, the NLS analysis mode was used to selectively detect organic peroxides formed during β-pinene ozonolysis experiments. Overall, six organic peroxide structures were proposed. Further product-ion scan analysis on the six proposed structures revealed additional unique mass losses of 32 u and 62 u that could be use in combination with 34 u NLS analysis to selectively detect organic peroxides. The results from this study can assist in ascertaining organic peroxide contribution to secondary organic aerosol for future ozonolysis experiments.