大气中痕量挥发性有机物分析方法研究

Measurement Method Research on Trace Volatile Organic Compounds in Atmosphere

利用自行研制的累积式大气采样装置、大气痕量有机物二步冷冻浓缩进样系统和气相色谱/质谱(GC/MS)联用技术对大气中的痕量挥发性有机物进行分析(CCS-GC/MS),并对分析方法进行了评估.结果表明,CCS-GC/MS系统将单纯GC/MS分析大气中痕量挥发性有机物检测下限体积分数值从10-6量级扩展到10-12,39种目标化合物平均响应因子为2·9×10-12A-1,1000cm3进样量最低检出限体积分数值为7×10-12~40×10-12;流出峰保留时间定性分析相对平均偏差<2·5s,对目标化合物定性分析准确率达到100%;0~400×10-9浓度范围内外标定量曲线r2平均值大于0·99;回收率为88%~111%,平均值100·8%±5·6%;精密度误差2%~14%,平均6·6%.

An automated accumulation sampling system and a method of two-step Cryo-Concentrated System combined with Gas Chromatography/Mass Spectrometry (CCS-GC/MS) are introduced. The method is evaluated by a set of special experiments and the results are demonstrated. The lowest limit volume concentrations of the measurement is expanded from 10~ -6 to 10~ -12 using CCS-GC/MS instead of the normal method of GC/MS and the average response factor of 39 object compounds is 2.9×10~ -12·A~ -1. When injection volume of air sample reaches 1 000cm^3, the lowest limit is 7×10~ -12～40×10~ -12;CCS-GC/MS may identify all the objective chemical species in the atmosphere samples, with average 2.5s bias of retention time for 39 GC peaks. Within 0～400×10~ -9, the concentration of all the objective compounds can be calculated by standard curve individually (average r^2 above 0.99) and accurately. The recollect rate is 88%～111%, at average of 100.8%±5.6%; and the bias of precision is 2%～14%, at average of 6.6%.