Department of BioGeoChemistry and Analytics, Institute of Ecological Chemistry, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
Anal Chem. 2010 Oct 1;82(19):8017-26. doi: 10.1021/ac101444r.
Complementary molecular and atomic signatures obtained from Fourier transform ion cyclotron resonance (FTICR) mass spectra and NMR spectra provided unequivocal attribution of CHO, CHNO, CHOS, and CHNOS molecular series in secondary organic aerosols (SOA) and high-resolution definition of carbon chemical environments. Sulfate esters were confirmed as major players in SOA formation and as major constituents of its water-soluble fraction (WSOC). Elevated concentrations of SO(2), sulfate, and photochemical activity were shown to increase the proportion of SOA sulfur-containing compounds. Sulfonation of CHO precursors by means of heterogeneous reactions between carbonyl derivatives and sulfuric acid in gas-phase photoreactions was proposed as a likely formation mechanism of CHOS molecules. In addition, photochemistry induced oligomerization processes of CHOS molecules. Methylesters found in methanolic extracts of a SOA subjected to strong photochemical exposure were considered secondary products derived from sulfate esters by methanolysis. The relative abundance of nitrogen-containing compounds (CHNO and CHNOS series) appeared rather dependent on local effects such as biomass burning. Extensive aliphatic branching and disruption of extended NMR spin-systems by carbonyl derivatives and other heteroatoms were the most significant structural motifs in SOA. The presence of heteroatoms in elevated oxidation states suggests a clearly different SOA formation trajectory in comparison with established terrestrial and aqueous natural organic matter.
傅里叶变换离子回旋共振（FTICR）质谱和 NMR 谱获得的互补分子和原子特征，明确归因于二次有机气溶胶（SOA）中的 CHO、CHNO、CHOS 和 CHNOS 分子系列，并对碳化学环境进行高分辨率定义。硫酸盐酯被确认为 SOA 形成的主要参与者，也是其水溶性部分（WSOC）的主要成分。研究表明，SO2、硫酸盐和光化学活性的升高会增加 SOA 含硫化合物的比例。通过羰基衍生物和气相间光化学反应中硫酸之间的多相反应，提出了 CHO 前体的磺化作用作为 CHOS 分子的可能形成机制。此外，光化学诱导了 CHOS 分子的聚合过程。在强光化学暴露下的 SOA 的甲醇提取物中发现的甲酯被认为是通过甲醇解从硫酸盐酯衍生而来的二次产物。含氮化合物（CHNO 和 CHNOS 系列）的相对丰度似乎相当依赖于局部影响，如生物质燃烧。羰基衍生物和其他杂原子对扩展 NMR 自旋系统的广泛脂肪支化和破坏是 SOA 中最重要的结构特征。高价态杂原子的存在表明，与已建立的陆地和水相天然有机物相比，SOA 的形成轨迹明显不同。
