水中林丹的固相微萃取与气相色谱耦合研究

Analysis of Lindane in Water by Using Modified Solid-phase Microextraction Coupled with Gas Chromatography

介绍了一种改进的固相微萃取技术（SPME）、气相色谱-电子捕获检测器（GCLECD）联用测定水中林丹的新方法.该法将萃取了林丹的PDMS纤维用少量有机溶剂解吸,解吸后的有机溶剂进入气相色谱检测,从而实现固相微萃取与自动进样器的耦合.通过评价吸附时间、解吸时间、温度、pH等条件对萃取效率的影响,确定如下实验条件：吸附时间120min、解吸时间60min、室温（25℃）.当林丹加标浓度为20ng/mL时,该法与GC-ECD耦合后的回收率为82%,检测限为21ng/L,相对标准偏差为0.8%,浓度—响应曲线在2.5-40ng/mL时呈线性（R2=0.993,N=5）.该法已应用到太湖水样中林丹的监测.

A modified solid-phase microextraction method was developed by immersing the Solid-phase microextraction（SPME） fiber into a small volume of organic solvent for desorption contrary to injecting fiber into the hot injector of the gas chromatograph system for analysis. The main parameters affecting the modified SPME process including adsorption time, desorption time, and temperature were investigated for the SPME fiber coated with poly dimethylsiloxane （PDMS）. Adsorption of 120 rain, desorption of 60 rain and temperature of 25℃ were selected in the method. Coupled to gas chromatograph / electron capture detector （GC/ECD）, the recovery of lindane was in a level 82% when spiked in the level of 20 ng/mL （N=5）, and the calibration curve was linear （R^2 =0. 993） in the range between 2.5 and 40 ng/mL for the analysis. The method offered a detection limit of 0. 021 ng/mL and a relative standard deviation （RSD） of 0. 8% （n = 5） for lindane in spiked level of 20 ng/mL. Applicability of the method to the determination of lindane in real water samples collected from Lake Taihu has also been demonstrated.