聚氨酯泡沫塑料吸附-电感耦合等离子体质谱(ICP-MS)法测定地球化学样品中的痕量金

Adsorption and Thiourea Desorption of Trace Gold in Geochemical Samples by Foam Plastics

探讨了聚氨酯泡沫塑料的预处理、样品浓度、水洗条件、基体元素对金吸附率的影响等因素。结果表明,用泡沫塑料吸附含金量为5 ng~500μg的溶液,吸附率均在90%以上。影响聚氨酯泡沫塑料吸附率的重要条件是振荡前要用水充分浸透,水洗基体元素,矿渣宜在酸性环境下进行。铁、钛等离子可以提高吸附率,钠、钙、锌、矿渣等影响不显著,铝离子有微弱的抑制作用。ICP-MS的灵敏度与介质的雾化率有一定的相关性,应当使用硫脲介质的工作溶液作工作曲线,内标元素可用103Rh或185Re,但是对于高含量W样品,只能使用103Rh作内标。用金矿石国家标准物质做精密度与准确度验证,测定值与标准值无显著差异,相对标准偏差(RSD)均小于10%,精密度能满足地球化学样品中痕量金的分析要求。

The factors such as pretreatment of polyurethane foam,sample concentration,washing conditions and the effect of matrix elements on gold adsorption rate were discussed.The results showed that the gold content of the solution adsorbed by foam plastics ranged from 5 ng to 500μg,and the adsorption rate was above 90%.The important conditions that affect the adsorption rate of polyurethane foam plastics are that the base elements should be thoroughly soaked with water,and the slag should be washed in acidic environment before oscillation.Iron and titanium can improve the adsorption rate,sodium,calcium,zinc and slag are have less of effect,aluminum can cause little inhibition.The sensitivity of ICP-MS has a certain correlation with the atomization rate of the medium.The working solution of thiourea medium should be used as the working curve.The internal standard elements can be 103Rh or 185Re,but only 103Rh can be used for high W samples.The method is accurate and reliable,The results show that RSD<10%,and it can meet the requirements of gold analysis and analysis in geochemical samples.