顶空固相微萃取-气相色谱-质谱法测定废水中痕量挥发性烷基硫化物

Determination of Trace Volatile Alkyl Sulfides in Wastewater by Headspace Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry

建立了顶空固相微萃取(HS-SPME)和气相色谱/质谱(GC/MS)联用测定人工湿地废水中的痕量挥发性烷基硫化物的方法。针对废水中两种主要的挥发性烷基硫化物(二甲基硫、二甲基二硫),详细研究了萃取纤维头的种类、萃取时间、萃取温度、pH值、离子强度、样品量及解析条件对HS-SPME的影响。载气为高纯氦气,流速为1.0mL/min,色谱柱为DB-5ms毛细管柱(0.25μm,30m×0.32mm),柱温:25℃(5min)■40℃(1min)■60℃(5min);在优化的实验条件下,本法测定二甲基硫及二甲基二硫的线性范围分别为10～10000ng/L和1～10000ng/L;检出限(3σ)分别为1.9ng/L和1.8ng/L;相对标准偏差小于10%;回收率分别为81.0%～94.6%和84.0%～100.9%。用二乙基硫为内标物质,将本法用于人工湿地废水中主要的烷基硫化物二甲基硫和二甲基二硫的测定,获得满意结果。

A headspace solid phase microextraction （HS-SPME） followed by gas chromatography coupled to mass spectrometry （GC-MS） has been developed for the determination of trace volatile alkyl sulfides （VASs） in wastewater from constructed wetlands. The various parameters including type of fibers, extraction time, extraction temperature, pH value, ionic strength, sample volume and desorption conditions were investigated for optimization of HS-SPME performance for dimethyl sulfide and dimethyl disulfide in wastewater. The high purity helium with a flow rate of 1 mL/min and DB-5 ms capillary column （30 m ×0.32 mm, 0.25 μm） were used for separation of dimethylsulfide and dimethyldisulfide by GC. The oven temperature was programmed at 25℃ for 5 min, then a rate of 5 ℃/min until 40 ℃, holding 1 min, and then a rate of 15 ℃/min until 260 ℃, holding the final temperature for 5 min. The experimental results show that the linear dynamic ranges were 10 - 10000 and 1 - 10000 ng/L for dimethylsulfide and dimethyldisulfide, respectively. The detection limit （3σ） for dimethylsulfide and dimethyldisulfide were 1.9 and 1.8 ng/L, respectively. The relative standard deviations for the determination of studied compounds were less than 10%, and recoveries range from 81.0% to 94.6% and 84.0% to 100.9% for dimethylsulfide and dimethyldisulfide, respectively. By using diethyl sulfide as internal standard, the proposed method has been successfully applied to the determination of dimethylsulfide and dimethyldisulfide in wastewater with satisfactory results.