Contribution of Selected Dicarboxylic and ω-Oxocarboxylic Acids in Ambient Aerosol to the m/z 44 Signal of an Aerodyne Aerosol Mass Spectrometer
Contribution of Selected Dicarboxylic and ω-Oxocarboxylic Acids in Ambient Aerosol to the m/z 44 Signal of an Aerodyne Aerosol Mass Spectrometer
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DOI：
10.1080/02786820701203215
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发表时间：
2007-03
影响因子：
5.2
通讯作者：
N. Takegawa;T. Miyakawa;Kimitaka Kawamura;Yutaka Kondo
中科院分区：
文献类型：
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作者：
N. Takegawa;T. Miyakawa;Kimitaka Kawamura;Yutaka Kondo
Aerodyne气溶胶质谱仪（AMS）采用闪蒸（600°C），然后采用70 eV电子碰撞电离（EI）来检测有机和无机气溶胶。质荷比（m/z）44（主要是CO2+）处的信号被认为是含氧有机气溶胶的最可靠标志。本研究首次评估了选定的低分子量二羧酸（二元酸）和ω-氧代羧酸（ω-氧代酸）对AMS质谱的颗粒相m/z 44信号的贡献。2003年8月3日至8日，在东京（35°39 ′ N，139°40 ′ E）的一个地面站点进行了环境测量。二酸和ω-含氧酸使用过滤器采样，然后进行萃取、衍生和气相色谱-火焰离子化检测器（GC-FID）分析来测量。在测量期间，二元酸和ω-含氧酸的质量浓度与m/z44信号有密切的相关性（r2 = 0.85-0.94）。还进行了实验室实验，以确定环境气溶胶中选定的二酸（C2-C6二酸和邻苯二甲酸）和ω-含氧酸（乙醛酸）的碎片模式。在这里，我们首次报告了在测量期间所选择的有机酸可以平均占所观察到的m/z 44信号的14 ± 5%。草酸（C2）是最大的贡献者，占观察到的m/z 44信号的10 ± 4%。这些结果将有助于解释从不同位置的环境测量中获得的m/z 44信号。
The Aerodyne aerosol mass spectrometer (AMS) employs flash vaporization (600°C) followed by 70-eV electron impact ionization (EI) to detect organic and inorganic aerosols. The signal at mass-to-charge ratio (m/z) 44 (mainly CO 2 + ) is considered the most reliable marker of oxygenated organic aerosol. This study is the first to evaluate the contribution of selected low molecular weight dicarboxylic acids (diacids) and ω-oxocarboxylic acids (ω-oxoacids) to the particle-phase m/z 44 signal of the AMS mass spectrum. Ambient measurements were conducted at a surface site in Tokyo (35°39 ′ N, 139°40 ′ E) during August 3–8, 2003. Diacids and ω-oxoacids were measured using a filter sampling followed by extraction, derivation, and gas chromatograph-flame ionization detector (GC-FID) analysis. The mass concentrations of diacids and ω-oxoacids show tight correlation with the m/z 44 signal (r 2 = 0.85–0.94) during the measurement period. Laboratory experiments were also performed to determine the fragment patterns of selected diacids (C2–C6 diacids and phthalic acids) and ω-oxoacid (glyoxylic acid) in ambient aerosols. Here, we report for the first time that the selected organic acids could account for 14 ± 5% of the observed m/z 44 signal on average during the measurement period. Oxalic acid (C2) is the largest contributor, accounting for 10 ± 4% of the observed m/z 44 signal. These results would be useful for interpreting the m/z 44 signals obtained from ambient measurements in various locations.