Secondary organic material formed by methylglyoxal in aqueous aerosol mimics Department of Chemical Engineering, Columbia University, New York, NY, USA
Received: 15 July 2009 – Published in Atmos. Chem. Phys. Discuss.: 24 July 2009 Abstract. We show that methylglyoxal forms light-absorbing secondary organic material
in aqueous ammonium sulfate and ammonium nitrate solutions mimicking
tropospheric aerosol particles. The kinetics were characterized using UV-Vis
spectrophotometry. The results suggest that the bimolecular reaction of
methylglyoxal with an ammonium or hydronium ion is the rate-limiting step
for the formation of light-absorbing species, with kNH4+II=5×10−6 M−1 min−1 and kH3O+II≤10−3 M−1 min−1. Evidence of aldol condensation products and
oligomeric species up to 759 amu was found using chemical ionization mass
spectrometry with a volatilization flow tube inlet (Aerosol-CIMS). Tentative
identifications of carbon-nitrogen species and a sulfur-containing compound
were also made using Aerosol-CIMS. Aqueous solutions of methylglyoxal, with
and without inorganic salts, exhibit significant surface tension depression.
These observations add to the growing body of evidence that dicarbonyl
compounds may form secondary organic material in the aerosol aqueous phase,
and that secondary organic aerosol formation via heterogeneous processes may
affect seed aerosol properties.
Revised: 13 January 2010 – Accepted: 14 January 2010 – Published: 01 February 2010
Citation: Sareen, N., Schwier, A. N., Shapiro, E. L., Mitroo, D., and McNeill, V. F.: Secondary organic material formed by methylglyoxal in aqueous aerosol mimics, Atmos. Chem. Phys., 10, 997-1016, doi:10.5194/acp-10-997-2010, 2010.