Effective Henry's law partitioning and the salting constant of glyoxal in aerosols containing sulfate.

The reversible partitioning of glyoxal was studied in simulation chamber experiments for the first time by time-resolved measurements of gas-phase and particle-phase concentrations in sulfate-containing aerosols. Two complementary methods for the measurement of glyoxal particle-phase concentrations are compared: (1) an offline method utilizing filter sampling of chamber aerosols followed by HPLC-MS/MS analysis and (2) positive matrix factorization (PMF) analysis of aerosol mass spectrometer (AMS) data. Ammonium sulfate (AS) and internally mixed ammonium sulfate/fulvic acid (AS/FA) seed aerosols both show an exponential increase of effective Henry's law coefficients (KH,eff) with AS concentr…