吸收液采样-顶空-气相色谱法测定废气中吡啶

用吸收液采集废气样品,顶空进样,采用气相色谱法测定进样气体中吡啶的含量。用DB-FFAP毛细管色谱柱分离,氢火焰离子化检测器测定。优化的试验条件如下:①采用多孔玻板吸收瓶采集样品;②吸收液的体积为45mL;③采样流量为0.5L·min^-1;④样品在4℃下,7d内完成分析;⑤吸收液的pH大于12;⑥加入3g氯化钠调节吸收液离子强度;⑦顶空温度为80℃,顶空平衡时间为30min。吡啶的质量浓度在100mg·L^-1以内与其对应的峰面积呈线性关系,检出限为0.05 mg·m^-3。对3个不同浓度水平的吡啶标准气体进行测定,相对误差为-8.0%^-4.7%,测定值的相对标准偏差(n=6)为1.3%~7.8%。

GC Determination of Pyridine in Waste Gas with Absorption Liquid Sampling and Headspace

Absorption liquid was used as collection of the waste gas sample.After headspace sampling,GC was applied to the determination of pyridine in the sampling gas.The analyte was separated on DB-FFAP capillary chromatographic column and detected by hydrogen flame ionization detector.The optimized conditions found were as follows:① porous glass plate absorption bottle was used for sample collection;② volume of absorption solution was 45 mL;③sampling flow was 0.5 L·min^-1;④ the sample was analyzed within 7 days at 4 ℃;⑤ pH of absorption solution was more than 12;⑥ 3 g sodium chloride was added to adjust the ionic strength of absorption solution;⑦the temperature and equilibrium time of headspace were set at 80 ℃ and 30 min.Linear relationship between values of peak area and mass concentration of pyridine was kept in the range within 100 mg·L^-1,with detection limit of 0.05 mg· m^-3.Three standard gases of pyridine with different concentration levels were determined,giving relative errors in the range of-8.0%--4.7% with RSDs(n=6)of determination values in the range of 1.3%-7.8%.