氢氧化镁共沉淀-电感耦合等离子体原子发射光谱法测定矿石样品中钍

Determination of thorium in mineral samples by inductively coupled plasma atomic emission spectrometry after preconcentration through coprecipitation of magnesium hydroxide

矿石样品被Na2O2熔融分解后,用沸热的三乙醇胺(5+95)浸取熔块,样品中Fe、Al和Ti与三乙醇胺络合而进入碱性溶液。向溶液中加入适量MgCl2溶液(20g/L),形成的Mg(OH)2与微量钍共沉淀,用沸热的HCl(1+2)溶解过滤后沉淀物,以波长283.730{118}nm作为分析线,在选定的仪器参数下以电感耦合等离子体原子发射光谱法测定了溶液中的钍。本方法样品前处理简单、快速,且在波长283.730{118}nm处钍未受到其它元素明显的光谱干扰,溶液中钍原子发射光谱强度与钍的质量浓度在0～2μg/mL范围内呈良好的线性关系,校准曲线相关系数r为0.999 9,方法检出限为0.038μg/mL。用本方法测定了标准物质中钍的含量,测定值与认定值吻合,相对标准偏差(n=6)在0.54%～3.9%范围内。

The mineral samples were melted and decomposed by Na2O2.After being leached with 100 mL of hot triethanolamine（5＋95）,Fe,Al and Ti in mineral samples could be dissolved into the base solution to form complex with triethanolamine.And the coprecipitates of Mg（OH）2 and trace thorium were formed by adding 2 mL of MgCl2（20 g/L）into the solution.After filtering,the coprecipitates were then dissolved with hot HCl（1＋2）,and the content of thorium in the solution was determined by inductively coupled plasma atomic emission spectrometry at 283.730{118}nm under the selected instrumental parameters.The pretreatment of sample was simple and fast;moreover,the spectrum interference of other elements on thorium was not significant at the wavelength of 283.730{118}nm.There was a good linear relationship between emission intensity of thorium and the mass concentration of Th in the solution in the range of 0-2 μg/mL.The correlation coefficient of calibration curve was 0.999 9,and the detection limit of this method was 0.038 μg/mL.The content of thorium in CRMs was determined by this method and the results were consistent with the certified values,with the relative standard deviation（n=6） between 0.54%-3.9%.