搅拌棒吸附萃取-热脱附-气相色谱-质谱联用法测定水中54种挥发性有机物

Determination of 54 kinds of volatile organic compounds in water samples by stir bar sorptive extraction-thermodesorption-gas chromatography-mass spectrometry

目的采用搅拌棒吸附萃取(SBSE)-热脱附-气相色谱-质谱联用法测定水样中54种挥发性有机物(VOCs)。方法涂有聚二甲基硅氧烷(PDMS)的搅拌棒置于20 ml水样中,以1 500 r/min萃取20 min后热脱附-气相色谱-质谱联用仪检测。研究了萃取体积、不同浓度Na Cl、不同浓度甲醇、搅拌棒转速和萃取时间对萃取效率的影响;分别对影响SBSE萃取效率的条件进行了优化,同时也对热脱附的时间、温度和冷阱温度等条件进行优化。结果 54种VOCs的浓度为0.5μg/L^100μg/L时,线性关系良好,相关系数(r)为0.994 3~0.999 9,检出限为0.03μg/L^6μg/L,相对标准偏差(RSD)为1.09%~5.02%,平均加标回收率为81.6%~99.6%(n=10)。结论本法简便、快速,准确度和灵敏度高,检出限低,稳定性好,干扰小,线性范围宽,无有机溶剂污染,可满足多种水样中54种VOCs的测定。

Objective Stir bar sorptive extraction（ SBSE） in combination with thermodesorption-gas chromatography-mass spectrometry（ TD-GC-MS） was applied for the determination of the 54 kinds of volatile organic compounds（ VOCs） in water samples. Methods The stir bar coated with polydimethylsiloxane（ PDMS） was added to 20 ml of water sample and stirred at1 500 r / min for 20 min. Then,the stir bar was subjected to TD-GC-MS. The effects of extraction volume,salt addition,methanol addition,stir bar speed and extraction time on extraction efficiency were studied. SBSE extraction conditions were optimized. Thermal desorption time,temperature and cold trap temperature and other conditions were optimized. Results The linearity was good when the concentrations of 54 kinds of VOCs were among 0. 5 μg / L-100 μg / L,with correlation coefficients of0. 994 3-0. 999 9,the detection limit of 0. 03 μg / L-6 μg / L,the relative standard deviation（ RSD） of 1. 09%-5. 02%,and the average recovery rates of 81. 6%-99. 6%（ n = 10）. Conclusion The method is simple,rapid,accurate and sensitive with low detection limit,good stability,little interference,wide linear range,and no solvent pollution,which can meet the determination of 54 kinds of VOCs in a variety of water samples.