Department of Chemistry, University of California, Irvine, Irvine, California 92617, USA.
Anal Chem. 2010 Oct 1;82(19):8010-6. doi: 10.1021/ac1014386.
This work demonstrates the utility of a particle-into-liquid sampler (PILS), a technique traditionally used for identification of inorganic ions present in ambient or laboratory aerosols, for the analysis of water-soluble organic aerosol (OA) using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). Secondary organic aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and ozone in a 5 m(3) Teflon chamber. SOA was collected simultaneously using a traditional filter sampler and a PILS. The filter samples were later extracted with either water or acetonitrile, while the aqueous PILS samples were analyzed directly. In terms of peak abundances, types of detectable compounds, average O/C ratios, and organic mass to organic carbon ratios, the resulting high-resolution mass spectra were essentially identical for the PILS and filter based samples. SOA compounds extracted from both filter/acetonitrile extraction and PILS/water extraction accounted for >95% of the total ion current in the ESI mass spectra. This similarity was attributed to high solubility of limonene SOA in water. In contrast, significant differences in detected ions and peak abundances were observed for pine needle biomass burning organic aerosol (BBOA) collected with PILS and filter sampling. The water-soluble fraction of BBOA is considerably smaller than for SOA, and a number of unique peaks were detectable only by the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS analysis offers a new approach for molecular analysis of the water-soluble organic fraction in biogenic SOA, aged photochemical smog, and BBOA.
这项工作展示了粒子进液采样器（PILS）的实用性，该技术传统上用于识别环境或实验室气溶胶中存在的无机离子，现在可用于使用高分辨电喷雾电离质谱（HR-ESI-MS）分析水溶性有机气溶胶（OA）。在 5m³聚四氟乙烯室内，以 0.5ppm 的混合比将柠檬烯和臭氧混合产生二次有机气溶胶（SOA）。同时使用传统的滤膜采样器和 PILS 收集 SOA。滤膜样品随后分别用去离子水或乙腈提取，而 PILS 的水相样品则直接进行分析。就峰丰度、可检测化合物类型、平均 O/C 比和有机质量与有机碳比而言，PILS 和基于滤膜的样品的得到的高分辨质谱结果基本相同。从滤膜/乙腈提取和 PILS/水提取的 SOA 化合物分别占 ESI 质谱总离子流的 >95%。这一相似性归因于柠檬烯 SOA 在水中的高溶解度。相比之下，用 PILS 和滤膜采样收集的针叶林生物质燃烧有机气溶胶（BBOA）在检测离子和峰丰度方面存在显著差异。BBOA 的水溶性部分明显小于 SOA，并且只有通过滤膜/乙腈方法才能检测到许多独特的峰。PILS 采集与 HR-ESI-MS 分析相结合，为分析生物源 SOA、老化光化学烟雾和 BBOA 中的水溶性有机部分提供了一种新的分子分析方法。
