饮用水中4种氯酚的单液滴微萃取气相色谱-质谱测定方法研究

[目的]研究单液滴微萃取气相色谱-质谱法快速测定饮用水中4种氯酚的最优实验条件。[方法]取50 mL水样,加入内标2,4-二溴酚,经不同条件萃取和衍生后,采用气相色谱-质谱法检测定量。选择单液滴微萃取最佳实验条件,并应用于样本中4种氯酚的测定,再将测定结果与标准方法进行比较。[结果]实验显示最优条件分别为：萃取剂为正己烷-甲苯（1∶1）,衍生剂为N-叔丁基二甲基甲硅烷基-N-甲基三氟乙酰胺（MTBSTFA）,衍生剂比例为20%,搅拌速度为200 r/min,萃取时间为30 min,溶液离子强度为200 g/L的氯化钠溶液。在上述优化的实验条件下,2-氯酚、2,4-二氯酚、2,4,6-三氯酚、五氯酚在0.2~100.0μg/L质量分数范围内,其相关系数分别为0.999 3,0.999 3,0.998 7,0.999 9,检出限分别为0.021、0.018、0.026、0.035μg/L。在1、10、80μg/L三个氯酚水平的平均回收率在85.6%~104.0%,相对标准偏差为2.5%~9.4%。本法测定结果与标准方法比较,无统计学差异。[结论]本研究的优化实验条件下采用单液滴微萃取气相色谱-质谱法步骤简单,快速,与标准方法测定结果一致性高,适用于饮用水中氯酚的快速检测。

Determination of Four Chlorophenols in Drinking Water by Single-Drop Microextraction and Gas Chromatography-Mass Spectrometry

[ objective ] To identify the best experimental condition for simultaneous determination of four chlorophenols in drinking water by single-drop microextraction （SDME） and gas chromatography-mass spectrometry （GC-MS）. [ Methods ] The method involved addition of 2, 4-dibromophenol as internal standard into 50 mL water samples, followed by extraction and derivatization at different conditions, and quantification using GC-MS detection. The best conditions for SDME efficiency was applied to analyze four chlorophenols in drinking water. The results determined by this method were compared with those by the national standard method. [ Results ] The optimized conditions for SDME were summarized as follows： hexane-toluene （1 ： 1） as solvent; N-methyl-（tert-butyldimethylsilyl）trifluoroacetamide （MTBSTF） as derivatization reagent; 20% MTBSTFA; microextraction was performed in a medium of 200g/L NaC], with a stirring rate of 200r/min for 30min. Calibration curves for the four chlorophenols （2-chlorophenols, 2, 4-dichlorophenols, 2, 4, 6-trichlorophenols, and pentachlorophenols） were linear within the range of 0.2-100.0μg/L. The correlation coefficients were 0.999 3, 0.999 3, 0.998 7, and 0.999 9, respectively. The limits of detection were 0.021, 0.018, 0.026, and 0.035μg/L, respectively. The average recoveries ranged from 85.6% to 104.0% at three spiked levels of 1, 10, and 80μg/L for each chlorophenol, and the relative standard deviations ranged from 2.5% to 9.4%. No significant difference was found in the results between the proposed method and the national standard method. [ Conclusion ] The proposed method is simple, rapid, highly consistent with the standard method, and thus suitable for the determination of chlorophenols in drinking water.