Validation of in-situ measurements of volatile organic compounds through flask sampling and gas chromatography/mass spectrometry analysis

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• 作者：Chih-Chung Chang ; Chang-Feng OuYang ; Chieh-Heng Wang ; Sen-Wei Chiang ; Jia-Lin Wang
• 关键词：Inter-comparison ; Non-methane hydrocarbons (NMHCs) ; Photochemical assessment monitoring stations (PAMS)
• 刊名：Atmospheric Environment
• 出版年：2010
• 出版时间：March 2010
• 年：2010
• 卷：44
• 期：10
• 页码：1301-1307
• 全文大小：466 K

文摘

Continuous monitoring of ambient non-methane hydrocarbons (NMHCs) by automated gas chromatographs equipped with flame ionization detection (termed in-situ GC/FID) with hourly data resolution was instated in ozone non-attainment areas throughout Taiwan. Performance of these on-site in-situ GCs was validated by manual flask sampling, as well as by in-lab gas chromatography/mass spectrometry (GC/MS) analysis. More than 50 VOCs from C₂ to C₁₁ were analyzed by both methods. Ninety flask samples were collected in series near an in-situ GC monitoring station in order to closely compare with the in-situ measurements. Both time-series and scatter plots from the two methods are displayed and discussed. It was found that over-simplified, un-humidified single-point calibration leading to surface loss was responsible for the bias in the in-situ method, resulting in greater error in accuracy as VOC volatility decreased. Although this over-estimate of the concentrations was found across all target VOCs, both methods were able to consistently capture the variability of ambient VOCs, with R² values greater than 0.9 for most of the major VOCs.