SOLVENT-EXTRACTION AND ORGANIC CARBON DETERMINATION IN ATMOSPHERIC PARTICULATE MATTER - ORGANIC EXTRACTION ORGANIC CARBON ANALYZER (OE-OCA) TECHNIQUE
SOLVENT-EXTRACTION AND ORGANIC CARBON DETERMINATION IN ATMOSPHERIC PARTICULATE MATTER - ORGANIC EXTRACTION ORGANIC CARBON ANALYZER (OE-OCA) TECHNIQUE
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DOI：
10.1021/ac60356a001
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发表时间：
1975-01-01
影响因子：
7.4
通讯作者：
GROSJEAN, D
中科院分区：
文献类型：
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作者：
GROSJEAN, D
本文介绍了一种测定大气气溶胶中有机碳的方法。它包括在玻璃纤维过滤器上收集的样品的有机溶剂萃取，然后用有机碳分析仪分析浓缩的萃取物在水中的悬浮液。在蒸发区（= 100 ℃）除去有机溶剂，在有机碳分析仪的燃烧区（T= 850 ℃）测量气溶胶有机碳。26种溶剂和24种二元混合物提取气溶胶有机物的能力。本文定义了以苯为萃取剂时的萃取效率EF和有机碳萃取效率OCEF。非极性溶剂具有确定的EF's和OCEF's，而极性溶剂EF和OCEF随采样期间观察到的臭氧浓度（即烟雾化学成分）而变化。EF与几种溶剂极性参数有很好的相关性。二氯甲烷和几种极性溶剂的EF和OCEF均高于苯，但没有一种单一溶剂能覆盖气溶胶有机物的所有极性范围。在苯萃取后，用极性溶剂（包括水）连续萃取，证明仅用苯萃取时，气溶胶有机物的重要部分（高达48%的有机碳）丢失了。极性和非极性溶剂的所有二元混合物具有比极性和非极性溶剂两者更高的OCEF。连续和二元混合物萃取给出相同的OCEF结果。极性溶剂可溶性无机物，主要是硝酸盐，可以很容易地通过在极性溶剂萃取后使用水萃取的差异来测量。用其他几种方法检验了OE-OCA方法的有效性。其中，建议对玻璃纤维过滤器进行直接OCA分析。本方法可提取和测定95 ~ 100%的气溶胶有机碳，特别适合于大气气溶胶有机碳的常规测定。它们的浓度通常通过有机溶剂萃取玻璃纤维过滤器上收集的样品来测量（1）。通过对有机提取物的化学分析获得更详细的信息：红外（2，3）和CHN分析（4，5），分级（5，6）和通过TLC（7），GC（8，9），UV-荧光（10，11）和质谱（12）分析特定化合物的每个馏分。然而，所有这些后续分析都取决于有机溶剂萃取效率（EF）。羟基和其他极性溶剂对有机颗粒物表现出良好的EF，但也能溶解大量的无机物，尤其是硝酸盐。因此，在缺乏合适的技术来常规测定这些极性溶剂中的有机碳的情况下，非极性溶剂过去被最广泛地用于提取大气有机物。例如，苯已被用于国家空气监测网络（13）和许多其他研究（4，5，8）。在使用的其他溶剂中，有环己烷（12，14，15），因为它的EF接近苯，毒性较小; CCl 4（16），因为它的IR透明度和CS2（17），因为它在GC中的火焰离子化检测器响应非常低。本研究的目的是双重的：表明单独用苯（或环己烷，或其他非极性溶剂）提取可能导致严重低估气溶胶有机物，并描述一种简单，准确的方法
A method is presented for the determination of organic car-bon In atmospheric aerosols. It consists of organic solvent extraction of samples collected on glass fiber filters followed by organic carbon analyzer analysis of the concen-trated extracts as suspension in water. The organic solvent Is removed in the vaporization zone(= 100 C) and the aerosol organic carbon is measured in the combustion zone (T= 850 C) of an organic carbon analyzer. Twenty-six solvents and 24 binary mixtures were studied for their ability to extract aerosol organics. We define for this purpose the parameters EF (extraction efficiency) and OCEF (organic carbon extraction efficiency) with benzene as refer-ence solvent. Nonpolar solvents have definite EF’s and OCEF’s, while polar solvents EF and OCEF vary with the ozone concentration (ie, the smog chemical composition) observed during the sampling period. EF’s correlate well with several solvent polarity parameters. Methylene chloride and several polar solvents have higher EF and OCEF than benzene, but none of the single solvents covers all the polarity rangeof the aerosol organics. Successive extrac-tions using polar solvents, Including water, after benzene extraction, Indicate that an Important fraction of aerosol or-ganics, up to 48% as organic carbon, Is missing using ben-zene extraction alone. All binary mixtures of a polar and a nonpolar solvent have higher OCEF than both polar and nonpolar solvents. Successive and binary mixtures extrac-tions give identical OCEF results. Polar-solvent soluble inor-ganics, mostly nitrates, can be easily measured by differ-ence using water extraction after polar solvent extraction. The validity of the OE-OCA technique Is tested against sev-eral others. Among them, the direct OCA analysis of glass fiber filters Is suggested. From 95 to 100% of the aerosol organic carbon is extracted and measured by the means of the proposed method, which seems particularly suitable for routine determination of atmospheric aerosol organic car-bon.Organic compounds are a significant fraction of the urban aerosols. Their concentration is usually measured by organic solvent extraction of samples collected on glass fiber filters (1). More detailed information is obtained by chemical analysis of the organic extracts: infrared (2, 3) and CHN analysis (4, 5), fractionation into classes (5, 6) and analysis of each fraction for specificcompounds by TLC (7), GC (8, 9), UV-fluorescence (10, 11) and mass spectrometry (12). However, all these subsequent analyses depend on the organic solvent extraction efficiency (EF). Hydroxylic and other polar solvents show a good EF for or-ganic particulate matter, but are able to dissolve a signifi-cant quantity of inorganics, especially nitrates, as well. Thus, in the absence of a suitable technique for routine or-ganic carbon determination in those polar solvents, nonpo-lar solvents were most widely used in the past for the ex-traction of atmospheric organics. For example, benzenehas been used for the National Air Surveillance Network (13) and numerous other studies (4, 5, 8). Among other solvents used áre cyclohexane (12, 14, 15) because its EF is close to that of benzene and it is less toxic; CCI4 (16) for its IR transparency and CS2 (17) because of its very low flame ionization detector response in GC. The purpose of this study is twofold: to show that ex-tracting with benzene (or cyclohexane, or other nonpolar solvents) alone may lead to a serious underestimation of aerosol organics, and to describe a simple, accurate method