To reduce the quantification uncertainty of commercial aerosol mass spectrometers (AMS) and aerosol chemical speciation monitors (ACSM), a new capture vaporizer (CV) was recently built to replace the standard vaporizer (SV). A collection efficiency (CE) ∼ 1 in the CV AMS/ACSM has been demonstrated for ambient aerosols, but the CV also leads to increased thermal decomposition of the analytes because of longer residence time and vaporizer surface contact. This study reports on the performance of the CV for analyzing organic aerosol (OA) elemental composition and source apportionment, using both HR-ToF-AMS and ACSM for the first time. The methodology for obtaining elemental ratios from AMS spectra is updated to account for differences in OA fragmentation between the CV and SV. An artifact CO⁺ signal is observed for some chemically reduced laboratory compounds. If that signal is included in elemental analysis, the O:C is substantial overestimated, while accurate results are observed if the anomalous CO⁺ is ignored. The estimated uncertainty of O:C (H:C) of standard organic species with the CV-AMS is 23% (18%). Consistent time series of positive matrix factorization (PMF) factors and their fractions of total OA were found across the CV and SV in the three very different ambient data sets ranging from biogenic- to anthropogenic-dominated, indicating limited loss of source determination information despite the increased fragmentation. In some cases, bootstrap analysis of CV data sets shows higher uncertainty for the apportionment of total oxygenated OA (OOA) into different subtypes than that of the SV data set, which is potentially due to lower signal-to-noise at larger m/z from the increased thermal decomposition in the CV.

中文翻译：

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新型用于气溶胶质谱仪（AMS）的捕集蒸发器的评估：有机气溶胶（OA）的元素组成和来源分配

为了减少商业气溶胶质谱仪（AMS）和气溶胶化学形态监测器（ACSM）的定量不确定性，最近建立了一个新的捕集蒸发器（CV）来代替标准蒸发器（SV）。已证明CV AMS / ACSM在环境气溶胶中的收集效率（CE）约为1，但由于更长的停留时间和蒸发器表面接触，CV也会导致分析物的热分解增加。这项研究首次报告了使用HR-ToF-AMS和ACSM分析CV来分析有机气溶胶（OA）元素组成和来源分配的性能。更新了从AMS光谱中获取元素比率的方法，以解决CV和SV之间的OA碎裂差异。神器CO ⁺观察到某些化学还原的实验室化合物的信号。如果该信号包括在元素分析中，则O：C会大大高估，而如果CO ⁺异常，则会观察到准确的结果被忽略。使用CV-AMS估算的标准有机物的O：C（H：C）不确定度为23％（18％）。在从生物基因到人为因素占主导的三个非常不同的环境数据集中，通过CV和SV发现了正矩阵分解因子（PMF）因子及其在总OA中所占比例的一致时间序列，这表明尽管碎片增加。在某些情况下，CV数据集的自举分析表明，将总含氧OA（OOA）分配给不同子类型的不确定性高于SV数据集，这可能是由于较大的m / z信号信噪比较低是由于CV中的热分解增加所致。