摘要
环境空气中VOCs的自动监测数据是研究重污染天气成因的一个重要依据。低温空管冷冻浓缩技术-GC-MSFID法,可用于环境空气中多组分VOCs复杂样品的自动监测,性能优于吸附管浓缩法。低温空管冷冻浓缩技术的采样流量、采样时间、冷冻温度等条件对环境空气中VOCs的测定有很大影响。实验结果表明:高采样流量低采样时间条件下,低沸点卤代烃捕集效率偏低;低采样流量长采样时间,-120℃捕集温度可满足各类VOCs的测试。降低采样流量增加采样时间,沸点较高的各类VOCs的捕集效率比较高。相同捕集温度下,降低采样体积,各类VOCs的响应同步降低,可用于高浓度C_5~C_(12)碳氢化合物、卤代烃和醛酮含氧化合物样品的测定。
Online monitoring data of VOCs in ambient air is very important for studying the cause of heavy pollution weather. In this article,online monitoring of VOCs based on cryo-trapping-GC-MS-FID method is proposed,which can realize the qualitative and quantitative research of complex compounds. This method is superior to adsorption tube condensation. For cryo-trapping-GCMS-FID method,the sampling rate,sampling time,freezing temperature and other conditions have great influence on the determination of VOCs in the ambient air. Experimental results show that with high sampling rate and low sampling time,the trapping efficiency of low boiling halogenated hydrocarbons is low. With low sampling rate and long sampling time,capture temperature at -120 ℃ can meet all kinds of VOCs test. Reducing the sampling rate and prolong sampling time,the trapping efficiency of VOCs with high boiling point becomes relatively high. At the same trapping temperature,reducing the sampling volume,the response for all VOCs decrease accordingly,which can be used for measuring the trapping efficiency of high concentration C_5-C_(12) hydrocarbons,halogenated hydrocarbons,aldehyde and ketone oxygenated compounds.
引文
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