顶空气相色谱法测定污水中的苯系物

采用顶空气相色谱法测定了污水中的苯系物,该苯系物包括苯、甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯、异丙苯和苯乙烯。采用气相色谱-FID,AC-20弹性石英毛细管色谱柱,对气相色谱分析条件和顶空分析条件(水样体积、平衡温度、平衡时间、聚四氟乙烯膜及加盐量)进行了优化,使得各组分得到完全分离。实验结果表明,苯系物各组分在质量浓度6~1 000μg/L内均与峰面积呈良好的线性关系,相关系数大于0.999;最佳顶空分析条件为:试样用量8mL、平衡温度60℃、平衡时间20min、氯化钠用量2.0g、使用聚四氟乙烯膜隔离水样和密封硅橡胶垫。在最佳分析条件下,该方法的检出限为1.1~1.3μg/L,相对标准偏差为1.3%~5.2%(n=6),加标回收率为85.3%~103.6%(n=3)。该方法快速、准确,可监测污水处理厂进、出水中苯系物的含量。

Determination of Benzene Series in Sewage Water by Headspace Gas Chromatography

An analytical method for determination of the benzene series in sewage water by headspace gas chromatography was studied.The main objects of the analysis were benzene,toluene,ethylbenzene,p-xylene,m-xylene,o-xylene,cumene and styrene.The influences of sample volume,equilibration time,equilibration temperature,polytetrafluoroethylene isolating film and sample salinity on the determination were investigated.The benzene series were completely separated on an AC-20 capillary column(30 m×0.32 mm×0.5 μm) and determined by GC equipped with FID.The experimental results indicated good linear correlations of the working curves of the benzene series and the linearity ranges were in 6-1 000 μg/L.The linear regression coefficients were more than 0.999.The optimal conditions for the headspace gas chromatographic analysis were sample volume 8 mL,equilibration temperature 60 ℃,equilibrating time 20 min,NaCl dosage 2.0 g and using polytetrafluoroethylene isolating film.Under the optimal conditions,the detection limits were in a range of 1.1-1.3 μg/L and the relative standard deviations were in 1.3%-5.2%(n was 6).The recoveries were 85.3%-103.6%(n was 3).Determination of the benzene series in influent and effluent of the sewage plant by the method indicated that benzene series were disposed completely by the sewage treatment process.