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Development of an In Situ Dual-Channel Thermal Desorption Gas Chromatography Instrument for Consistent Quantification of Volatile, Intermediate Volatility and Semivolatile Organic Compounds
Atmospheric Measurement Techniques ( IF 3.8 ) Pub Date : 2021-06-07 , DOI: 10.5194/amt-2021-156
Rebecca A. Wernis , Nathan M. Kreisberg , Robert J. Weber , Yutong Liang , John Jayne , Susanne Hering , Allen H. Goldstein

Abstract. Aerosols are a source of great uncertainty in radiative forcing predictions and have poorly understood health impacts. Most aerosol mass is formed in the atmosphere from reactive gas phase organic precursors, forming secondary organic aerosol (SOA). Semivolatile organic compounds (SVOCs) (effective saturation concentration, C*, of 10−1–103 μg m−3) comprise a large fraction of organic aerosol, while intermediate volatility organic compounds (IVOCs) (C* of 103–106 μg m−3) and volatile organic compounds (VOCs) (C* ≥ 106 μg m−3) are gas phase precursors to SOA and ozone. The Comprehensive Thermal Desorption Aerosol Gas Chromatograph (cTAG) is the first single instrument simultaneously quantitative for a broad range of compound-specific VOCs, IVOCs and SVOCs. cTAG is a two-channel instrument which measures concentrations of C5–C16 alkane equivalent volatility VOCs and IVOCs on one channel and C14–C32 SVOCs on the other coupled to a single High Resolution Time of Flight Mass Spectrometer, achieving consistent quantification across 15 orders of magnitude of vapor pressure. cTAG obtains concentrations hourly and gas–particle partitioning for SVOCs bihourly, enabling observation of the evolution of these species through oxidation and partitioning into the particle phase. Online derivatization for the SVOC channel enables detection of more polar and oxidized species. In this work we present design details and data evaluating key parameters of instrument performance such as I/VOC collector design optimization, linearity and reproducibility of calibration curves obtained using a custom liquid evaporation system for I/VOCs and the effect of an ozone removal filter on instrument performance. Example timelines of precursors with secondary products are shown and analysis of a subset of compounds detectable by cTAG demonstrates some of the analytical possibilities with this instrument.

中文翻译:

开发一种原位双通道热脱附气相色谱仪,用于对挥发性、中等挥发性和半挥发性有机化合物进行一致定量

摘要。气溶胶是辐射强迫预测中极大不确定性的来源,并且对健康影响知之甚少。大多数气溶胶物质在大气中由反应性气相有机前体形成,形成二次有机气溶胶 (SOA)。半挥发性有机化合物 (SVOC)(有效饱和浓度 C* 为 10 -1 –10 3  μg m -3)包含大部分有机气溶胶,而中等挥发性有机化合物 (IVOC)(C* 为 10 3 –10 6  μg m -3 ) 和挥发性有机化合物 (VOC) (C* ≥ 10 6  μg m -3) 是 SOA 和臭氧的气相前体。综合热解吸气溶胶气相色谱仪 (cTAG) 是第一台同时定量分析多种特定化合物 VOC、IVOC 和 SVOC 的单一仪器。cTAG 是一种双通道仪器,可在一个通道上测量 C 5 –C 16烷烃等效挥发性 VOC 和 IVOC 的浓度以及 C 14 –C 32另一方面,SVOC 与单个高分辨率飞行时间质谱仪耦合,在 15 个数量级的蒸气压上实现一致的量化。cTAG 每小时获取一次浓度,每半小时获取一次 SVOC 的气体-颗粒分配,从而能够观察这些物质通过氧化和分配到颗粒相的演变过程。SVOC 通道的在线衍生化能够检测更多极性和氧化的物质。在这项工作中,我们介绍了评估仪器性能关键参数的设计细节和数据,例如 I/VOC 收集器设计优化、使用定制的 I/VOC 液体蒸发系统获得的校准曲线的线性和再现性以及臭氧去除过滤器对仪器性能。
更新日期:2021-06-07
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