敞开酸溶-氦气模式ICP-MS法测定土壤和沉积物中银钨锑等9种元素及在找矿中的应用

Determination of Nine Elements including Ag, W, and Sb in Soils and Sediments by Helium Mode ICP-MS with Open-Vessel Acid Digestion and Its Application to Mineral Exploration

  • 摘要: 测定土壤和沉积物中Ag、W、Sb、Ba、Cu、Pb、Zn、Co、Ni元素时,W难溶且易水解,Sb在高温下易挥发损失,ICP-MS测试时Ag同位素(107Ag和109Ag)受Zr、Nb质谱干扰显著。本文采用敞开三酸(硝酸-氢氟酸-高氯酸)消解,王水复溶(120~150℃),硝酸提取,内标元素选择Rh和Re,在氦气模式下,分别进行了Zr、Nb对107Ag和109Ag的干扰试验,通过氦气模式结合离线干扰校正氧化物91Zr16O+93Nb16O+107Ag和109Ag干扰,实现了一次溶样、一次进样、一种模式ICP-MS同时测定Ag等9种元素。采用6种土壤和6种水系沉积物标准物质进行验证,方法检出限、精密度、正确度优于DZ/T 0130.4—2006的要求,与标准方法比对结果显示符合技术规范要求。实际应用于分析1527件9种元素测定范围跨度较大的土壤和沉积物样品,元素报出率100%,监控样(标准物质)测定结果准确度、精密度符合规范要求,分析结果的地质成图效果反映出9种元素的分布特征与地层、构造、岩石、矿化的关系密切,成图效果与地质背景吻合。本方法解决了传统ICP-MS测定Ag的干扰以及Ag、W、Sb等多元素协同分析的技术难点,简捷高效、成本低。

     

    Abstract: When determining Ag, W, Sb, Ba, Cu, Pb, Zn, Co and Ni in soil and sediment samples, W is difficult to dissolve and prone to hydrolysis, Sb is volatile at high temperatures, and the Ag isotopes (107Ag and 109Ag) are significantly interfered by Zr and Nb oxides during ICP-MS analysis. In this study, an open-vessel digestion method was employed using a mixture of three acids (nitric acid–hydrofluoric acid–perchloric acid), followed by re-dissolution with aqua regia at temperatures ranging from 120℃ to 150℃ and extraction with nitric acid. Rh and Re were selected as internal standard elements, and interference tests for Zr and Nb oxides on 107Ag and 109Ag were conducted separately in He mode. By combining He mode with offline interference correction, the interference of oxides 91Zr16O+ and 93Nb16O+ on 107Ag and 109Ag was corrected, enabling the simultaneous determination of nine elements through one digestion, one sample introduction, and one mode. Method verification was performed using six soil and six sediment reference materials, which demonstrated that the method’s detection limit, precision, and accuracy exceeded the requirements specified in DZ/T 0130.4-2006. Compared with standard methods, the results were in compliance with technical specifications. The proposed method was then applied to the analysis of 1527 soil and sediment samples covering a broad range of nine elements. The reporting rate for these elements reached 100%, with the accuracy and precision of the monitoring samples (standard materials) aligning with specified requirements. The spatial distribution of the nine target elements, as revealed by geological mapping analysis, demonstrated strong correlations with stratigraphic units, structural features, lithological variations, and mineralization patterns. These mapping results aligned closely with the regional geological framework. Thus, this method addresses the technical difficulties associated with traditional ICP-MS determination, such as Ag interference and the simultaneous analysis of multiple elements including Ag, W, and Sb. Overall, the method is simple, efficient, and cost-effective.

     

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