捕集阱顶空-气相色谱-质谱法测定饮用水中4种嗅味物质的含量

Determination of 4 Odor Substances in Drinking Water by Gas Chromatography-Mass Spectrometry with Trap Headspace

提出了捕集阱顶空-气相色谱-质谱法(GC-MS)同时测定饮用水中二甲基二硫醚、二甲基三硫醚、2-甲基异莰醇、土臭素4种嗅味物质的含量。取10.0 mL水样置于顶空瓶中,迅速加入3.0 g氯化钠,在0.276 MPa、70℃条件下加热平衡15 min,捕集阱循环4次后在DB-624色谱柱上按照柱升温程序分离,质谱分析采用多反应监测(MRM)模式,外标法定量。结果表明,4种嗅味物质的质量浓度在5.0~100.0 ng·L^(−1)内与对应的峰面积呈线性关系,检出限(3S/N)为0.6~2.5 ng·L^(−1)。按照标准加入法进行回收试验,回收率为95.0%~107%,测定值的相对标准偏差(n=6)均小于5.0%。方法用于10份生活饮用水样的分析,其中2份样品中检出二甲基二硫醚,检出量为4.7,2.4 ng·L^(−1),其余3种嗅味物质均未检出。

A method for the determination of 4 odor substances in drinking water,including dimethyl disulfide,dimethyl trisulfide,2-methylisocamphenol,and soil odor,was proposed by gas chromatography-mass spectrometry with trap headspace.10.0 mL of water sample was taken and placed in a headspace bottle,and 3.0 g of sodium chloride was added quickly.The mixture was heated and equilibrated at 0.276 MPa and 70℃for 15 min,and separated on a DB-624 chromatographic column according to the column heating program after the trap was cycled 4 times.Multiple reaction monitoring(MRM)mode was adopted in mass spectrometry analysis,and the external standard method was used for quantitative analysis.As shown by the results,linear relationships between the corresponding peak areas and mass concentrations of 4 odor substances were found in the range of 5.0-100.0 ng·L^(−1),with detection limits(3S/N)in the range of 0.6-2.5 ng·L^(−1).Test for recovery was made by the standard addition method,giving results in the range of 95.0%-107%,with RSDs(n=6)of the determined values less than 5.0%.This method was used for the analysis of 10 samples of drinking water,and dimethyl disulfide in 2 samples was detected,with detection amouts of 4.7 ng·L^(−1)and 2.4 ng·L^(−1),while the remaining 3 odor substances were not detected.