微波消解-ICP-MS法测定土壤中的汞

Determination of mercury in soils by ICP-MS with microwave digestion

建立一种利用微波消解预处理样品,ICP-MS法测定土壤中汞含量的方法。分析微波消解程序的设定、汞的记忆效应、质谱干扰和非质谱干扰对检测结果的影响,并给出解决办法。分析检测结果表明,微波消解温度为180℃、保持时间为15 min时,土壤中汞回收率良好;盐酸和汞形成络合物可减少汞的记忆效应,并保持汞的稳定性;选择内标元素Rh可有效校正非质谱干扰;选择同位素202Hg作为检测对象并开启氦气碰撞模式,可减少质谱干扰。汞元素浓度在0~5μg/L的范围内,其标准曲线线性关系良好,线性相关系数达到0.999 6;土壤标准物质GBW-07401a测定值符合证书参数;土壤样品多次检测相对标准偏差为3.8%,样品加标回收率为105%;方法检出限为0.001 mg/kg。该方法易操作、检出限低、精准度高,适用于土壤中汞的定量分析。

A method for determining mercury content in soil is established based on microwave digestion pretreatment in combination with inductively coupled plasma mass spectrometry(ICP-MS). The influences on parameter setting of the microwave digestion program and the memory effect of mercury are discussed, as well as analyses on mass spectrum interference and non-mass spectrum interference. According to experimental analysis, good recovery rate of mercury from the soil is attained when the microwave digestion temperature is kept at 180 °C and a duration at 15 min, the formation of haloacid complex reduces the memory effect of mercury and maintains the stability of mercury, the selection of internal standard element Rh can effectively avoid non-mass spectrum interference, selecting isotope 202Hg as test object and turning on the helium collision mode can reduce mass spectrum interference. The concentration of mercury element in the range of 0-5 μg/L shows a good linear relationship between the standard curve, with a linear correlation coefficient up to 0.999 6.The measured value of the standard reference material for soil(GBW-07401a) is in compliance with the certificate parameter, the relative standard deviation of multiple tests for soil sample is 3.8%, the recovery rate of sample spiking is 105%, and the detection limit is 0.001 mg/kg. This method is easy-to-operate and suitable for quantitative analysis of mercury in soil with low detection limit and high accuracy.