大气中痕量挥发性有机物分析方法研究

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%.

Measurement Method Research on Trace Volatile Organic Compounds in Atmosphere

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 x 10(-12) x A(-1). When injection volume of air sample reaches 1000 cm3, the lowest limit is 7 x 10(-12) - 40 x 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 x 10(-9), the concentration of all the objective compounds can be calculated by standard curve individually (average r2 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%.