Atmospheric Chemistry Department (ACD) , Leibniz Institute for Tropospheric Research (TROPOS) , Leipzig 04318 , Germany.
Environ Sci Technol. 2019 Oct 1;53(19):11353-11363. doi: 10.1021/acs.est.9b03839. Epub 2019 Sep 13.
A 2D-liquid chromatographic fractionation method was combined with direct infusion electrospray ionization Fourier transform-ion cyclotron resonance mass spectrometry to better resolve the high complexity of the organic material in atmospheric particles. The number of assigned molecular formulas increased by a factor of 2.3 for the fractionated sample (18 144) compared to a bulk sample analysis without fractionation (7819), while simultaneously allowing the identification of 71 240 isomeric compounds. Accounting for these isomers has an impact on the means and distributions of different descriptive sample parameters. More than 15 000 compounds were exclusively identified in the fractionated sample providing insights regarding the formation of organosulfates, reduced N-containing compounds, and polyaromatic compounds. Further, a new method for assigning organonitrates and poly-organonitrates based on Kendrick mass defect analysis is presented. The current study implicates that analytical separation leads to much more detailed insights into particle organics composition, while more commonly applied direct infusion MS studies can strongly underestimate composition complexity and lead to biased assignments of bulk organic properties. Overall, the particle organics composition is far more complex than previously shown, while separation through better chromatographic techniques helps to understand formation processes of atmospheric particle constituents.
采用二维液相色谱分离法与直接进样电喷雾电离傅里叶变换离子回旋共振质谱联用，以更好地解析大气颗粒物中有机物质的高度复杂性。与未进行分离的全样本分析（7819 个）相比，分离后的样本（18144 个）中分配的分子式数量增加了 2.3 倍，同时还允许鉴定 71240 个同分异构体。这些同分异构体的存在会影响不同描述性样本参数的平均值和分布。在分离样本中，有 15000 多种化合物是唯一鉴定出来的，这为有机硫酸盐、含氮还原化合物和多环芳烃化合物的形成提供了新的见解。此外，还提出了一种基于肯德里克质量缺陷分析来分配有机硝酸盐和多有机硝酸盐的新方法。本研究表明，分析分离可以更详细地了解颗粒物有机成分，而更常用的直接进样 MS 研究可能会严重低估成分复杂性，并导致对整体有机性质的有偏差的分配。总的来说，颗粒物的有机成分远比之前显示的要复杂得多，而通过更好的色谱技术进行分离有助于了解大气颗粒物成分的形成过程。
