固相微萃取-气相色谱-质谱法测定地表水中10种痕量苯系物

Determination of 10 Trace Benzene Series in Surface Water by Gas Chromatography-Mass Spectrometry with Solid Phase Micro-Extraction

采用多孔聚偏氟乙烯膜包裹多壁碳纳米管制备成多孔膜保护固相微萃取装置,该装置经水洗涤、甲醇活化、干燥后,放入1 L样品中,包膜以500 r·min^(-1)的速率搅拌30 min,吸附富集痕量苯系物。取出包膜,在1 mL甲醇中解吸5 min后获得浓缩的苯系物样品,经气相色谱-质谱法分析,比对NIST 14谱库并结合标准品的气相色谱保留时间对其中的10种痕量苯系物进行定性,采用外标法定量。结果表明,应用自制的固相微萃取装置,可有效去除体系的基质干扰,提高萃取效率,与NIST 14谱库比对定性,富集的10种苯系物的匹配度均不小于90%,说明方法定性准确。定量分析时,10种苯系物的质量浓度在1.000~1 000 ng·L^(-1)内与对应的峰面积呈线性关系,检出限为0.010~0.013 ng·L^(-1)。按照标准加入法进行回收试验,回收率为97.5%~100%,测定值的相对标准偏差(n=5)为0.89%~1.5%。方法用于测定12份实际水样,其中1份样品中氯苯检出量为179.0 ng·L^(-1),1份样品中对二甲苯检出量为151.0 ng·L^(-1)。

Porous polyvinylidene fluoride membrane was used to wrap multi-walled carbon nanotubes(MWCNTs) to prepare a solid phase micro-extraction device. After water washing, methanol activating and drying, the device was put into 1 L of the sample, and the coating was stirred at a rate of 500 r·min^(-1)for 30 min to adsorb and enrich trace benzene series. The coating was taken out and desorbed for 5 min in 1 mL of methanol to get the benzene series sample concentrated, in which 10 trace benzene series were analyzed by gas chromatography-mass spectrometry. 10 trace benzene series were identified by compared with NIST 14 spectrum library and the gas chromatographic retention time of the standards, and quantified by external standard method. As shown by the results, the application of self-made solid phase micro-extraction device could effectively remove the matrix interference of the system and improve extraction efficiency. Compared with NIST 14 spectrum library, the matching degree of 10 enriched benzene series was not less than 90%, indicating that qualitative analysis for this method was accurate. In quantitative analysis, linear relationships between values of peak area and mass concentration of 10 benzene series were found in the range of 1.000-1 000 ng·L^(-1), with detection limits in the range of 0.010-0.013 ng·L^(-1). Test for recovery was made by standard addition method, giving results in the range of 97.5%-100%, with RSDs(n=5) of the determined values ranged from 0.89% to 1.5%. This method was applied to determination of 12 actual water samples, among which the detection amount of chlorobenzene in one sample was 179.0 ng·L^(-1)and that of paraxylene in the other sample was 151.0 ng·L^(-1).