Uptake of Glyoxal by Organic and Inorganic Aerosol

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The uptake of glyoxal by a variety of organic and inorganic aerosol types was examined in a Teflon chamber. Rapid glyoxal uptake was observed for all liquid-phase aerosols at all relative humidity levels tested (50% RH). Even for aerosol with known water content, Henry’s Law cannot predict glyoxal uptake: H* > (3 ± 1.5) × 108 mol kg−1 atm−1 for l-tartaric acid, H* > (1 ± 0.5) × 108 for dl-malic acid and H* = (2 ± 1) × 107 for malonic acid aerosol. Other liquid-phase aerosol particles containing amine functional groups (arginine, aspartic acid, and glutamic acid) took up even more glyoxal (H* > 3 × 108). The trend of higher glyoxal uptake onto aerosol containing more nucleophilic organic compounds suggests that glyoxal is reacting with organic compounds in the aerosol phase. Solid-phase aerosol showed RH-dependent glyoxal uptake, likely due to the existence of surface water layers. However, particle growth rates were the highest for sodium sulfate aerosol. For organic aerosol, growth rates correlated with the acidity of the carboxylic acid groups of the aerosol material, suggesting that glyoxal uptake is enhanced by mildly acidic conditions.