A method for real-time detection of PAN, PPN and MPAN in ambient air

A selected ion flow drift tube (SIFDT) apparatus and a proton transfer reac tion mass spectrometer (PTR-MS) were used to study the reactions of protona ted water H3O+ and the proton bound water dimer (H2O)(2)H+ with PAN (peroxy acetic nitric anhydride, CH3C(O)OO NO2), PPN (peroxypropionic nitric anhydr ide, CH3CH2C (O)OONO2) and MPAN (peroxymethacrylic nitric anhydride, CH2C(C H3)C(O)OONO2). The protonated hydrates react rapidly with PAN, PPN and MPAN . Product ion peaks using ambient air as reactant gas could be unequivocall y :attributed to PAN, PPN and MPAN utilizing the thermal decomposition of t hese compounds on a hot surface. The results demonstrate that (H2O)(n)H+ (n =1,2) ions are excellent reagent ions for the real-time detection of PAN an d other organic nitrates in ambient air.