优化BCR法-ICP-MS在土壤重金属化学形态分析中的应用

为了研究土壤重金属元素的化学形态,以优化的BCR法模拟自然环境条件,连续提取了不同土壤标准物质中Cd、Cr、Cu、Ni、Pb、Zn的交换态、还原态、氧化态;采用微波混酸(5mL HNO_3+2 mL HCl+1 mL HF)消解土壤样品,电感耦合等离子体质谱法(ICP-MS)分析测定,在碰撞反应池模式(CCT)下以¹¹⁵In和²⁰⁹Bi双内标加入法进行信号漂移补偿和干扰校正;以形态分析标准参考物质(欧盟RCR-701)验证了方法的准确性。结果表明,CCT动态模式能有效地降低检测过程中多原子离子的干扰作用,检测分析方法的检出限均小于0. 2 ng/g,RSD <1. 35%(n=5),方法验证性实验说明所选方法准确可靠;土壤样品中各元素3种化学形态与残渣中含量的加和均与总量参考值接近,回收率在95%～110%之间;该法适于土壤重金属形态的提取和分析测定,对研究土壤重金属的赋存特征、迁移转化规律及影响因素、重金属元素的来源及土壤重金属污染的治理与修复有一定的指导意义。

Application of Improved BCR and ICP-MS Method in Determination of Chemical Forms of Heavy Metals in Soil

Natural environment conditions were simulated by improved BCR method in order to study the chemical forms of heavy metals in soil and exchangeable form,reducible form,oxidable form,residual form of heavy metals(Cd,Cr,Cu,Ni,Pb,Zn)in soil certified reference material were extracted continuously.The mixed system of microwave digestion was composed of 5mL HNO 3,2 mL HCl and 1 mL HF.Content of elements in each form was determined by inductively coupled plasma mass spectrometry.The internal standard elements^115In and^209Bi were used to compensate for matrix suppression effect and sensitivity drift based on the CCT model.Accuracy of the extraction method was verified using standard reference materials for speciation analysis(EU BCR701).The result showed that interference of polyatomic ions can be effectively reduced by CCT mode in the process of detection and analysis.The detection limits was less than 0.20 ng/g and RSD<1.35%(n=5).The sum of the content of each element was close to the total amount and recovery rate was 95%-110%.Results of confirmatory experiments showed that the coincidence degree was fine.Method validation experiments showed that the selected method was accurate and reliable.The method was suitable for extraction and analysis of heavy metal forms in soil.It has important guiding significance for studying the occurrence characteristics,migration and transformation rules and influencing factors of heavy metals,sources of heavy metals and remediation and remediation of heavy metal pollution in soil.