A laboratory flow reactor with gas particle separation and on-line MS/MS for product identification in atmospherically important reactions

摘要

A system to study the gas and particle phase products from gas phasehydrocarbon oxidation is described. It consists of a gas phase photochemicalflow reactor followed by a diffusion membrane denuder to remove gases fromthe reacted products, or a filter to remove the particles. Chemical analysisis performed by an atmospheric pressure chemical ionization (APCI) triplequadrupole mass spectrometer. A diffusion membrane denuder is shown toremove trace gases to below detectable limits so the particle phase can bestudied. The system was tested by examining the products of the oxidation ofm-xylene initiated by HO radicals. Dimethylphenol was observed in both thegas and particle phases although individual isomers could not be identified.Two furanone isomers, 5-methyl-2(3H)furanone and 3-methyl-2(5H)furanone wereidentified in the particulate phase, but the isobaric product 2,5 furandionewas not observed. One isomer of dimethyl-nitrophenol was identified in theparticle phase but not in the gas phase.