Field evidence for enhanced generation of reactive oxygen species in atmospheric aerosol containing quinoline components
Field evidence for enhanced generation of reactive oxygen species in atmospheric aerosol containing quinoline components
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DOI：
10.1016/j.atmosenv.2022.119406
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发表时间：
2022-10
影响因子：
5
通讯作者：
Wenjun Zhang;Haoran Yu;A. Hettiyadura;V. Verma;A. Laskin
中科院分区：
文献类型：
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作者：
Wenjun Zhang;Haoran Yu;A. Hettiyadura;V. Verma;A. Laskin
大气颗粒物（PM）中的有机组分对颗粒相活性氧（ROS）的迅速产生有重要作用，而活性氧的产生通常用其氧化电位（OP）来定量。在这项研究中，我们使用了先进的分子表征和OP定量的互补方法，以探索不同的有机物种，以提高环境气溶胶样品中的ROS生成的潜力。我们使用了在美国中西部收集的7个PM2.5样品，并将它们依次提取到一组具有不同极性的溶剂中：首先是非极性己烷（HEX），然后是中等极性二氯甲烷（DCM），最后是极性去离子（DI）水。使用固相萃取进一步分离DI提取物以将水溶性有机碳（WSOC）与无机离子分离。使用二硫苏糖醇（DTT）测定法分析获得的提取物的OP，并在此以DTT消耗速率（称为DTT活性）报告。使用高效液相色谱（HPLC）串联平台结合光电二极管阵列检测器（PDA）和高分辨率质谱仪（HRMS）分析相同提取物的分子组成。在WSOC组分中观察到最高的DTT活性（>1.1 μM min−1），其次是DCM（0.75-1.1 μM min−1）和HEX（<0.75 μM min−1）组分。这些结果得到了HPLC-PDA-HRMS分子表征数据的补充，表明在WSOC馏分中检测到许多氧化还原活性极性有机物。特别是，在所有DTT活性组分中系统地发现了具有元素式C11 H11 N的化学组分-归因于二甲基喹啉（DMQ）。喹啉的吡啶环中的未质子化的氮原子促进氧化还原反应中的电子转移，催化含喹啉样品中ROS的产生。这是第一项明确确定喹啉作为环境有机气溶胶复杂混合物中确定的ROS生成促进剂的研究。
Organic constituents of atmospheric particular matter (PM) contribute significantly to prompt generation of reactive oxygen species (ROS) in particle phase, which is often quantified in terms of its oxidative potential (OP). In this study, we used complementary methods of the advanced molecular characterization and the OP quantitation to explore potential of different organic species to enhance ROS generation in ambient aerosol samples. We used seven PM2.5samples collected in the Midwest US, and extracted them sequentially into a set of solvents with different polarity: first non-polar hexane (HEX), then moderately polar dichloromethane (DCM) and finally polar deionized (DI) water. The DI extracts were further separated using solid phase extraction to isolate water-soluble organic carbon (WSOC) from inorganic ions. The OP of obtained extracts was analyzed using dithiothreitol (DTT) assay and reported here in terms of the DTT consumption rate (called DTT activity). The molecular composition of the same extracts was analyzed using a tandem platform of high-performance liquid chromatography (HPLC) coupled with a photodiode array detector (PDA) and a high-resolution mass spectrometer (HRMS). Highest DTT activities were observed in WSOC fractions (>1.1 μM min−1) followed by DCM (0.75–1.1 μM min−1) and HEX (<0.75 μM min−1) fractions, respectively. These results were complemented by the HPLC-PDA-HRMS molecular characterization data indicating numerous redox-active polar organics detected in the WSOC fractions. In particular, chemical component with elemental formula of C11H11N - attributed to dimethyl quinoline (DMQ) - was found systematically across all DTT-active fractions. The unprotonated nitrogen atom in the pyridine ring of quinolines facilitates electron transfer in the redox reactions, catalyzing generation of ROS in the quinoline containing samples. This is the first study that unambiguously identifies quinoline as a promoter of ROS generation determined within complex mixtures of ambient organic aerosols.