title: First Quantification of Imidazoles in Ambient Aerosol Particles: Potential Photosensitizers, Brown Carbon Constituents, and Hazardous Components.
abstract: Imidazoles are widely discussed in recent literature. They have been studied as a secondary product of the reaction of dicarbonyls with nitrogen containing compounds in a number of laboratory studies, potentially acting as photosensitizers triggering secondary organic aerosol growth and are forming constituents of light absorbing brown carbon. Despite the knowledge from laboratory studies, no quantitative information about imidazoles in ambient aerosol particles is available. Within the present study, five imidazoles (1-butylimidazole, 1-ethylimidazole, 2-ethylimidazole, imidazol-2-carboxaldehyde, and 4(5)-methylimidazole) were successfully identified and quantified for the first time in ambient aerosol samples from different environments in Europe and China. Their concentrations range between 0.2 and 14 ng/m(3). 4(5)-Methylimidazole was found to be the most abundant imidazole. The occurrence of imidazoles seems to be favored at sites with strong biomass burning influence or connected to more polluted air masses. No connection was found between aerosol particle pH and imidazole concentration. Our work corroborates the laboratory studies by showing that imidazoles are present in ambient aerosol samples in measurable amounts. Moreover, it further motivates to explore the potential photosensitizing properties of small alkyl-substituted imidazoles.
authors.affiliation: Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Saxony, Germany.
authors.forename: Monique
authors.initials: M
authors.lastname: Teich
authors.affiliation: Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Saxony, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: van Pinxteren
authors.affiliation: Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Saxony, Germany.
authors.forename: Simonas
authors.initials: S
authors.lastname: Kecorius
authors.affiliation: Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Saxony, Germany.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Saxony, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Herrmann
mesh_terms: D000336:Aerosols / Q000032:analysis* / Q000737:chemistry; D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring / Q000379:methods; D005060:Europe; D007093:Imidazoles / Q000032:analysis*; D017319:Photosensitizing Agents / Q000032:analysis* / Q000737:chemistry
chemical_list: C510842:2-ethylimidazole; D000336:Aerosols; D000393:Air Pollutants; D007093:Imidazoles; D017319:Photosensitizing Agents; D002244:Carbon; C023439:4-methylimidazole