Elemental Composition of HULIS in the Pearl River Delta Region, China: Results Inferred from Positive and Negative Electrospray High Resolution Mass Spectrometric Data
Elemental Composition of HULIS in the Pearl River Delta Region, China: Results Inferred from Positive and Negative Electrospray High Resolution Mass Spectrometric Data
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DOI：
10.1021/es300285d
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发表时间：
2012-07-17
影响因子：
11.4
通讯作者：
Yu, Jian Zhen
中科院分区：
文献类型：
--
作者：
Lin, Peng;Rincon, Angela G.;Yu, Jian Zhen
采用正负模式电喷雾电离与超高电离联用技术，对珠江三角洲农村地区中国收获季节采集的气溶胶样品中的类腐殖质(HULIS)组分进行了分析。分辨率质谱仪(UHRMS)。ESI-UHRMS具有显著的分辨率和质量精度，鉴定了数千个元素公式。由于电离机制的不同，正(ESI+)和负(ESI-)模式下检测到的公式相辅相成，两者的使用提供了对HULIS更完整的表征。通过去质子化，在ESI-中优先检测到由C、H和O原子组成的化合物，这意味着它们的酸性。串联MS和Kendrick质量缺陷分析表明，CHO化合物中含有丰富的羧基，这一特征类似于天然元素组成的黄腐酸，但在HULIS样品中观察到相对较小的分子量。与EST-相比，在ESI+中观察到更多的还原氮有机化合物。生物质燃烧来源的化合物，包括生物碱、氨基酸及其衍生物是它们的可能成分。在ESI-中主要检测到含硫物种。这些物种的MS/MS谱图中含有硫酸盐碎片，且O/S比值较高，表明它们主要是有机硫酸盐。有机硫酸盐和硝氧基有机硫酸盐往往是ESI光谱中最强烈的峰。它们被认为是酸性硫酸盐颗粒对活性挥发性有机化合物的光氧化产物进行反应性吸收的产物。由UHRMS分析得出的元素组成证实了我们先前研究得出的结论，即生物质燃烧和SOA的形成都是珠江三角洲地区HULIS的重要来源。
The HUmic-LIke Substances (HULIS) fraction isolated from aerosol samples collected at a rural location of the Pearl River Delta Region (PRD), China, during the harvest season was analyzed by both positive and negative mode electrospray ionization (ESI) coupled with an ultrahigh. resolution mass spectrometer (UHRMS). With the remarkable resolving power and mass accuracy of ESI-UHRMS, thousands of elemental formulas were identified. Formulas detected in the positive (ESI+) and the negative (ESI-) mode complement each other due to differences in the ionization mechanism, and the use of both provides a more complete characterization of HULIS. Compounds composed of C, H, and O atoms were preferentially detected in ESI- by deprotonation, implying their acidic properties. Tandem MS and Kendrick Mass Defect analysis implies that carboxyl groups are abundant in the CHO compounds This feature is similar to those of natural Elemental compositions fulvic acids, but relatively smaller molecular weights are observed in the HULIS samples. A greater number of reduced nitrogen organic compounds were observed in the ESI+ compared to EST-. Compounds with biomass burning origin including alkaloids, amino acids, and their derivatives are their probable constituents. Sulfur containing species were dominantly detected in ESI-. The presence of sulfate fragments in the MS/MS spectra of these species and their high O/S ratios implies that they are mainly organosulfates. Organosulfates and nitrooxy-organosulfates were often the most intensive peaks in the ESI- spectra. They are believed to be products of reactive uptake of photooxidation products of reactive volatile organic compounds by acidic sulfate particles. The elemental compositions deduced from the UHRMS analysis confirm the conclusion from our previous study that biomass burning and SOA formation are both important sources of HULIS in the PRD region.