By using liquid chromatography system coupled with electrospray ionization source, UV/vis light detection and tandem Quadropole-Orbitrap mass spectrometer, we identified the most probable structures of 100 Brown carbon (BrC) chromophores in atmospherically-relevant samples including ambient aerosols, biomass burning aerosols, road tunnel aerosols, toluene+NOx secondary organic aerosol (SOA) and rainwater. These chromophores were classified into 9 groups, that is, 31 nitrophenols, 12 benzoic acids, 11 oxygenated polycyclic aromatic hydrocarbons (OPAHs), 10 phenols, 10 aryl amides/amines, 9 phenylpropene derivatives, 9 coumarins and flavonoids, 5 pyridines, and 3 nitrobenzoic acids. Among them, aryl amides/amine chromophores, which were mostly found in rainwater, were reported for the first time. The identified chromophores accounted for 20.9%-83.5% of the total light absorption over the wavelength range of 300-400nm in the five types of samples. We discussed the characteristic chromophore groups in each sample and identical chromophores among different samples, especially between the source samples and ambient aerosols. Among the 100 BrC chromophores, the gas-particle distribution and diurnal variation of 13 chromophores in the atmosphere were detected confidently by an online high-resolution chemical ionization mass spectrometer (CIMS) equipped with a Filter Inlet for Gases and Aerosols (FIGAERO). It was observed that the chromophores containing nitro- group had higher nighttime concentrations, while those without nitro- group had higher daytime concentrations.
 

棕碳，大气