衍生化-溶剂提取-气质联用法测定水中痕量烷基汞

Determination of alkyl mercury in water by derivatization-solvent extraction-gas chromatography-mass spectrometry

建立衍生化-溶剂提取-气质联用(GC-MS)测定水中痕量烷基汞的分析方法。用巯基固相萃取柱富集水中的烷基汞,4 mol/L盐酸洗脱,在HAc-NaAc缓冲体系(pH 4~5)下与50μL四丙基硼化钠(1%THF)衍生反应,0.5 mL正己烷提取烷基汞的衍生物,采用气相色谱-质谱联用选择离子方式(SIM)进行检测,以4-溴氟苯为内标定量,在2~200 ng/L范围内线性良好,1 L水样中甲基汞和乙基汞的检出限可达1 ng/L以下。实际样品添加回收率在69.7%~80.9%之间,准确度好;平行5次进行精密度试验,相对标准差在8.5%~10.3%之间。结果表明:方法稳定性好、操作方法实用,可用于水中痕量烷基汞的测定。

A sensitive and repeatable method was developed and applied to determine alkyl mercury in water by derivatization-solvent extraction-gas chromatography-mass spectrometry(GC-MS).The water samples were extracted by SH solid-phase extraction column.The SPE column was eluted by 4 mol/L HCl and the acidic solution was adjusted to neutral.Then HAC-NaAC buffer(pH 4-5)and 50μL sodium tetrapropylborate(NaBPr4)solution(1%THF)were added to the solution.The derivatives can be completely extracted by 0.5 mL n-hexane.The analytes were determined by GC-MS in SIM mode and quantified by internal standard method.The results showed that the alkyl mercury derivatives had a good linear relationship in the rang 2 ng/L to 200 ng/L.The limits of detection were less than 1 ng/L in about 1 L water samples.The recoveries of the analytes in real water samples spiked with standards were all in the range of 69.7%to 80.9%.Th erelative standard deviations(RSD)were between 8.5%to 10.3%(n=5).The results show that the method is sensitive and accurate for the determination of the alkyl mercury in water samples.