微波消解-同位素稀释质谱法测量鱼中汞含量

建立了微波消解-同位素稀释电感耦合等离子体质谱法(ID-ICP-MS)，用于测定国际物质量咨询委员会(CCQM)K43.1比对样品剑鱼中汞含量。对质谱测量汞的条件进行了优化，同时为了消除汞的记忆效应，比较了5%(体积分数)HNO₃、1‰(体积分数)2-巯基乙醇以及交替使用5μg/gAu和10μg/g EDTA3种方法对仪器的清洗效果。实验结果表明：射频功率1500～1600W，载气流速1.18L/min，取样深度7.5～6.9mm，积分时间0.4s条件下，能够获得准确的同位素比值；5μg/g Au和10μg/g EDTA溶液交替清洗在同样的洗涤时间内可使仪器本底最低。本文方法测定鱼中汞含量的平均值为(5.26±0.15)mg/kg， 在标准值(5.30±0.24)mg/kg的不确定度范围内。

Determination of mercury in fish by microwave digestion-isotope dilution inductively coupled plasma mass spectrometry

A method for the determination of mercury in CCQM K43.1 swordfish by microwave d igestion isotope dilution inductively coupled plasma mass spectrometry (ID-ICP -MS) has been developed. The optimum measurement conditions for ICP-MS were fo und to be as follows: RF power of 1500-1600W; carrier gas flow of 1.18?L/min; sample depth of 7.5-6.9mm; integration time of 0.4s. The effects of washing with 5% (volume fraction) HNO₃, Au/EDTA, and 1‰ (volume fraction) 2-mercaptoethanol were compared, and the results indicated that Au (5μg/g)/EDTA (10μg/g) was suita ble for eliminating the mercury memory effect. The proposed ID-ICP-MS method h as been used to determine mercury in fish and the results (average value of (5.26±0.15)mg/kg) showed good agreement with the certified value (5.30±0.24) mg/kg).