A new method was developed for determination of toluene, ethylbenzene, xylene, m-xylene, o-xylene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene in water samples by GC-FID coupled with ultrasound assisted-emulsification liquid liquid microextraction (USA-ELLME). When the volume of sample was 50 mL,a good extraction efficiency was obtained by using 150μL n-hexane, 400 μL acetonitrile under ultrasonic extraction for 12 min, and the enrichment factor reached 333. The chromatographic conditions was as follows: DB-5MS capillary chromatographic column (30 m×0.25 mm,0.25μm) was used. Injector temperature was 220℃. FID temperature was 250℃. The initial temperature of column was 45℃, keeping for 3 min, then increased to 70℃ in 3℃/min, and then increased to 200℃ at 30℃/min and keeping for 2 min. Hydrogen flow rate was 10 mL/min. Make-up gas flow rate was 30 mL/min. Split ratio was 30:1. Under the optimized conditions, the mass concentration of mixed solutions for the seven benzene series in ranges of 0.08-1.00 mg/L had the linear relationships to the peak area with the correlation coefficient >0.9980. The method detection limits were ranged from 0.005 mg/L to 0.01 mg/L. Mixed working solutions of 0.10 mg/L for the seven benzene series were detected by 7 times, RSD were in the range of 1.5%-4.7%. The method had been applied to the school lake water and laboratory wastewater, the recoveries of seven benzene series ranged from 86.5% to 110.4%. The determination results met the requirements of trace analysis.%采用正己烷为萃取剂,乙腈为乳化剂,建立超声辅助-乳化液液微萃取-气相色谱法(USA-ELLME-GC)检测水中甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯、1,3,5-三甲苯,1,2,4-三甲苯的分析方法.当萃取剂正己烷为150μL,乳化剂乙腈为400μL,超声时间为12 min时,50 mL水溶液中苯系物被成功萃取到正己烷中,富集倍数达到333倍.色谱条件为:DB-5MS(30 m×0.25 mm,0.25μm)毛细管柱,进样口温度220℃,检测器(FID)温度250℃,程序升温(初始45℃保持3 min,3°C/min升温至70℃,再以30℃/min升至200℃保持2 min),氢气流量10mL/min,尾吹气流量30 mL/min,分流比30:1.在优化的萃取和色谱条件下,7种苯系物在0.08~1.00 mg/L浓度范围内与峰面积呈线性关系,相关系数均>0.9980,方法检出限为0.005~0.01 mg/L,质量浓度均为0.10 mg/L的苯系物的7次前处理及测定结果相对标准偏差RSD为1.5%~4.7%.建立的方法应用于学校内湖水和实验室废水中7种苯系物的测定,平均回收率为86.5%~110.4%,测定结果满足分析化学痕量分析要求.
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