title: Formation of nitrogen-containing oligomers by methylglyoxal and amines in simulated evaporating cloud droplets.
abstract: Reactions of methylglyoxal with amino acids, methylamine, and ammonium sulfate can take place in aqueous aerosol and evaporating cloud droplets. These processes are simulated by drying droplets and bulk solutions of these compounds (at low millimolar and 1 M concentrations, respectively) and analyzing the residuals by scanning mobility particle sizing, nuclear magnetic resonance, aerosol mass spectrometry (AMS), and electrospray ionization MS. The results are consistent with imine (but not diimine) formation on a time scale of seconds, followed by the formation of nitrogen-containing oligomers, methylimidazole, and dimethylimidazole products on a time scale of minutes to hours. Measured elemental ratios are consistent with imidazoles and oligomers being major reaction products, while effective aerosol densities suggest extensive reactions take place within minutes. These reactions may be a source of the light-absorbing, nitrogen-containing oligomers observed in urban and biomass-burning aerosol particles.
authors.affiliation: Department of Chemistry and Biochemistry, University of San Diego, San Diego, California 92110, United States. ddehaan@sandiego.edu
authors.forename: David O
authors.initials: DO
authors.lastname: De Haan
authors.forename: Lelia N
authors.initials: LN
authors.lastname: Hawkins
authors.forename: Julia A
authors.initials: JA
authors.lastname: Kononenko
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Turley
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Corrigan
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Tolbert
authors.forename: Jose L
authors.initials: JL
authors.lastname: Jimenez
mesh_terms: D000336:Aerosols / Q000032:analysis / Q000737:chemistry*; D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry; D000645:Ammonium Sulfate / Q000032:analysis / Q000737:chemistry*; D001272:Atmosphere / Q000737:chemistry; D007093:Imidazoles / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008744:Methylamines / Q000737:chemistry; D010316:Particle Size; D011765:Pyruvaldehyde / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013227:Steam; D014835:Volatilization
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D000588:Amines; D000596:Amino Acids; D007093:Imidazoles; D008744:Methylamines; D013227:Steam; D011765:Pyruvaldehyde; C027451:methylamine; D000645:Ammonium Sulfate