A comparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading
A comparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading
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DOI：
10.5194/amt-3-959-2010
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发表时间：
2010-01-01
影响因子：
3.8
通讯作者：
Sive, B. C.
中科院分区：
文献类型：
--
作者：
Ambrose, J. L.;Haase, K.;Sive, B. C.
2004年夏天，在AIRMAP大气监测站（位于新罕布什尔州达勒姆农村的汤普森农场（THF）），使用配有火焰离子化检测器（FID）的气相色谱系统（GC）和质子转移反应-质谱仪（PTR-MS）测量甲苯。通过GC-FID同时测量单萜，包括α-和β-蒎烯、异松油烯、δ（3）-<$烯和d-柠檬烯，表明单萜混合比相对于甲苯有很大的增强，中值和最大增强比分别类似于2和类似于30。GC-FID和PTR-MS甲苯测量之间进行了详细的比较，以测试PTR-MS的大气甲苯测量的条件下，往往占主导地位的生物排放的特异性。我们推导出PTR-MS甲苯测量中与单萜采样和分析相关的潜在干扰的定量估计，包括单萜及其一些主要羰基氧化产物通过与H3 O+，O-2（+）和NO+在PTR-MS漂移管中反应的裂解。PTR-MS和GC-FID甲苯测量具有良好的定量一致性，并且两个系统从仪器检测限到最大混合比（类似于0.5 ppbv）相互跟踪良好。PTR-MS与GC-FID甲苯测量值的相关性图由最小二乘回归方程y=（1.13 +/- 0.02）x-（0.008 +/- 0.003）ppbv描述，表明PTR-MS测量值中存在类似于13%的小正偏倚。偏倚对应于最高测量甲苯水平下的0.055 ppbv差异。这两个系统在60%的测量值的组合1 sigma测量精度内定量一致。在测得的混合比的离散度没有很好的相关性与增强的单萜。通过校正PTR-MS漂移管中单萜碎片的贡献，获得了两个系统之间更好的定量一致性;然而，改进很小（
Toluene was measured using both a gas chromatographic system (GC), with a flame ionization detector (FID), and a proton transfer reaction-mass spectrometer (PTR-MS) at the AIRMAP atmospheric monitoring station Thompson Farm (THF) in rural Durham, NH during the summer of 2004. Simultaneous measurements of monoterpenes, including alpha- and beta-pinene, camphene, Delta(3)-carene, and d-limonene, by GC-FID demonstrated large enhancements in monoterpene mixing ratios relative to toluene, with median and maximum enhancement ratios of similar to 2 and similar to 30, respectively. A detailed comparison between the GC-FID and PTR-MS toluene measurements was conducted to test the specificity of PTR-MS for atmospheric toluene measurements under conditions often dominated by biogenic emissions. We derived quantitative estimates of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products via reactions with H3O+, O-2(+) and NO+ in the PTR-MS drift tube. The PTR-MS and GC-FID toluene measurements were in good quantitative agreement and the two systems tracked one another well from the instrumental limits of detection to maximum mixing ratios of similar to 0.5 ppbv. A correlation plot of the PTR-MS versus GC-FID toluene measurements was described by the least squares regression equation y=(1.13 +/- 0.02)x-(0.008 +/- 0.003) ppbv, suggesting a small similar to 13% positive bias in the PTR-MS measurements. The bias corresponded with a similar to 0.055 ppbv difference at the highest measured toluene level. The two systems agreed quantitatively within the combined 1 sigma measurement precisions for 60% of the measurements. Discrepancies in the measured mixing ratios were not well correlated with enhancements in the monoterpenes. Better quantitative agreement between the two systems was obtained by correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube; however, the improvement was minor (