同位素稀释-液相色谱-电感耦合等离子质谱(ICP-MS)法测定大米中的甲基汞  

Determination of Methylmercury in Rice by Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry (ICP-MS)with Isotope Dilution

作　　者：韦秋叶 李潇[1] 逯海[1] 韦超[1] WEI Qiuye;LI Xiao;LU Hai;WEI Chao(Affiliation National Institute of Metrology,China,Beijing 100029,China;Guangxi Research Institute of Metrology&Test,Nanning,Guangxi 530200,China)

机构地区：[1]中国计量科学研究院,北京100029 [2]广西壮族自治区计量检测研究院,南宁530200

出　　处：《中国无机分析化学》2023年第12期1287-1292,共6页Chinese Journal of Inorganic Analytical Chemistry

基　　金：国家质量基础专项项目(2018YFF0212800,2018YFF0212801)。

摘　　要：目前国标方法GB 5009.17—2021测量样品中甲基汞(含量≤0.1 mg/kg)的精密度为20%、定量限为0.02 mg/kg,对于定量限以下的样品检测存在困难;为了能精确地测量国家食品安全检测领域关注的甲基汞污染物,通过在样品中加入同位素稀释剂后以GB 5009.17—2021国标方法进行样品前处理,以液相色谱分离出汞形态,用电感耦合等离子体质谱(ICP-MS)法检测同位素比值,考虑质量歧视效应后以同位素稀释质谱法定量,建立了同位素稀释-液相色谱-电感耦合等离子质谱法测定大米样品中甲基汞含量的方法。当样品中甲基汞含量在0.01~0.03 mg/kg时,方法的精密度为0.30%~22.8%,不确定度U为0.002~0.004 mg/kg,k=2。以鱼肉中总汞与甲基汞成分分析标准物质(GBW10029)作为质控样,测定得到三种大米样品中甲基汞含量(以Hg计)分别为(8±2)、(24±3)、(19±4) ng/g,经过不确定度评估后表明方法的准确度较高;质控样(GBW10029)甲基汞的证书值(以Hg计)为(0.84±0.03) mg/kg,而测量结果为(0.83±0.08) mg/kg,对质控样的测量结果说明方法可靠;同位素稀释法将浓度的测量转换成同位素的丰度比的测量,可避免前处理过程带来的误差,同位素稀释与质谱结合可用于大米中甲基汞的高精度分析。The precision of methylmercury(content≤0.1 mg/kg)in samples measured by the current national standard method GB 5009.17—2021 is 20%,and the quantitative limit is 0.02 mg/kg.It is difficult to measure samples below the quantitative limit.For high-precision measurement of methylmercury pollutants which is concerned in the field of national food safety testing,a method was established for the determination of methylmercury content in rice using isotope dilution-liquid chromatography-inductively coupled plasma mass spectrometry.Firstly,samples were extracted according to the method of GB 5009.17—2021 after adding isotope diluent.Secondly,mercury was separated by liquid chromatography.Finally,the isotopic ratios were detected by ICP-MS and quantified with isotope dilution method due to mass discrimination effects.When the methylmercury content in the sample was 0.01—0.03 mg/kg,the precision of this method was 0.30%—22.8%,and the uncertainty U was 0.002-0.004 mg/kg,k=2.Using the certified reference material of total mercury and methyl mercury in fish tissue(GBW10029)as the quality control sample,the methylmercury content(as Hg)in 3 kind of rice were(8±2),(24±3),and(19±4)ng/g,respectively.The uncertainty evaluation showed that the method had high accuracy.The measurement result was(0.83±0.08)mg/kg,which was consistent with the certificate value(as Hg)of methylmercury in the quality control sample[(0.84±0.03)mg/kg,GBW10029],which showed that the method was reliable.Furthermore,the isotope dilution method converted concentration measurement into isotopic abundance ratio measurement,which avoided errors caused by the preprocessing process.Therefore,the combination of isotope dilution and mass spectrometry can be applied in high accuracy analysis of methylmercury in rice.

关 键 词：同位素稀释质谱 形态分析 甲基汞 大米 

分 类 号：O657.63[理学—分析化学]