稳定性同位素内标-全自动固相膜萃取-气相色谱质谱联用测定水中多氯联苯

目的建立水体中20种多氯联苯(polychlorinated biphenyls,PCBs)的稳定性同位素内标-全自动固相膜萃取-气相色谱质谱联用测定法,并应用于实际水样的测定。方法采集福州瓶装矿泉水(地下水)、自来水(生活饮用水管道末梢水),闽侯大学城内河水(地表水)和溪源宫溪水(生活水源水)等水样,气相色谱质谱联用(gas chromatography-mass spectrometer,GC-MS)分析本底值,用含13C12稳定性同位素的PCBs定量内标(surrogate solution,SS)定量。各水样20、40和80 ng/L3个浓度加标(n=7),计算SS回收率进行前处理质控,计算PCBs回收率和相对标准偏差(relative standard deviation,RSD)以验证方法,并将此法用于闽江流域上游支流至下游入海口共17个横断面江水的测定。结果方法检出限(method detection limits,MDL)为1.9~6.6 ng/L,水样回收率为70.9%~127%,RSD为0.5%~13%,定量内标SS的回收率为40%~90%。实际水样均未检出PCBs。结论本方法采用全自动固相萃取膜技术,比传统手工固相萃取柱法节省试剂,自动化程度高,同时运用稳定性同位素内标,结合GC-MS技术,结果更准确可靠,可运用于实际水样PCBs的测定。

Determination of polychlorinated biphenyls in water by stable isotope dilution through automatic solid-phase extraction membrane coupled to gas chromatography-mass spectrometry

OBJECTIVE The method for analyzing of 20 polychlorinated biphenyls(PCBs) in water by stable isotope internal standard-automatic solid-phase extraction membrane(auto SPEM) coupled to gas chromatography-mass spectrometer(GC-MS) was established, and applied to the analysis of trace PCBs in water samples. METHODS The sample backgrounds of bottled mineral water production in Fuzhou(groundwater), inland water in Fuzhou university city(surface water), tap water(pipe tip water) and stream water in Xiyuan Gong(water source of life) were analyzed by GC-MS. Surrogate solution(SS)internal standards including 13C12 PCBs stable isotope was used for quantification. The method was confirmed by calculating recovery rate(RR) and relative standard deviation(RSD) of spiked water samples(20, 40 and 80 ng/L, n=7). And recovery rates of SS were used to evaluate the effect of the pretreatment. And the method was used to determine PCBs of a total of 17 cross-sectiona river water in minjiang river tributaries upstream to the downstream estuary. RESULTS The method detection limits(MDL) were 1.9-6.6 ng/L, and RRs were 70.9%-127%,and RSDs were 0.5%-13%. The RRs of SS were 40%-90%. Positive sample was not detected. CONCLUSION The method of auto SPEM is less solvent, more automatic than traditional manual SPE. And the method is more accurate and reliable by stable isotope internal standard coupled to GC-MS. Therefore, it is useful for the trace PCBs determination of waters.