多孔膜萃取/微捕集方法及在线测定水中挥发性有机物

摘要

Based on the membrane pervaporation extraction and microtrap process,a sample pretreatment device for volatile organic compounds in water was constructed and evaluated systematically.The volatile organic compounds (VOCs) in water samples could be extracted,preconcentrated,desorbed thermally,and then injected directly into gas chromatography automatically and continuously.Two kinds of membrane materials,polydimethylsiloxane (PDMS) and polyvinylidene fluoride (PVDF),extraction temperature,extraction time,and carrier gas flow rate were investigated with nine model compounds,chloroform,1,2-dichloroethane,carbon tetrachloride,trichloroethylene,tetrachloroethylene,toluene,ethylbenzene,styrene,chlorobenzene.Using this membrane extraction/microtrap device combined with gas chromatography and a flame ionization detector,under the conditions of 60 ℃ extraction temperature,30 min concentration time and 8 mL/min carrier gas flow,the detection limits of chlorinated hydrocarbons were in the range of 0.003-0.041 μg/L.The RSDs between 2.7％ and 13.0％ were obtained.Coefficients of correlation were all above O.9936.This result demonstrated that this device was very useful for monitoring volatile organic compounds in water.%基于多孔膜萃取水中挥发性有机物和微捕集技术,构建了一套水中挥发性有机物(Volatile Organic Compounds,VOCs)样品前处理装置,可自动、在线、连续完成水中挥发性有机物萃取、富集、热解析,传输给气相色谱分离检测.实验分别对膜萃取材料、萃取温度、萃取时间、吹扫气流速等进行了系统优化,并用于氯仿、1,2-二氯甲烷、四氯化碳、三氯乙烯、甲苯、四氯乙烯、乙苯、氯苯、苯乙烯9种挥发性有机物的检测.研究结果表明,采用膜萃取/微捕集装置,与气相色谱联用,在萃取温度60℃,萃取时间30 min,吹扫气流速8 mL/min条件下,采用氢焰离子化检测器(Flame ionization detector,FID),对氯代烃的检出限达到0.003～0.041 μg/L,精确度为2.7％ ～13.0％,线性相关系数均大于0.9936,适用于在线检测水中挥发性有机物.