电感耦合等离子体质谱法测定地球化学样品中镉

Determination of Cd in geochemical samples by inductively coupled plasma-mass spectrometry

采用HF-HClO4-HNO3-H2SO4分解样品,王水提取,选用4个国家一级标准物质制备成标准系列校准,ICP-MS法直接测定地球化学样品中的Cd。选择103Rh为内标,确定了仪器的最佳分析条件,研究了Zr,Sn对Cd的干扰,选择114Cd作为测定同位素,采用数学公式校正了Sn对Cd的同质异位素干扰,方法检测限(3s)为6.3×10-3μg/g,RSD(n=12)为3.9%～6.6%。经国家一级标准物质验证,测定值与标准值吻合较好。该方法适用于地球化学样品中的微量Cd的测定。

A method for the determination of heavy metal cadmium in geochemical samples by inductively coupled plasma spectrometry（ICP-MS） directly was described.The samples were digested by 4 acids,HF-HClO4-HNO3-H2SO4,and were extracted by aqua regia.Four national standard materials were chosen and made into series solutions for external calibration method.114Cd was chosen as the determining isotope and 103Rh as the internal standard.The instrument operating parameters were optimized and the interference from coexistent elements of Zr,Sn to the determination of Cd was studied.Interference from Sn isobars to Cd was calibrated by a mathematical method.The detection limit of the method for Cd is 6.3×10-3 μg/g.The method has been applied to the determination of Cd in National Standard Reference Materials and the results are in good agreement with certified values with relative standard deviations of 3.9%~6.6%（n=12）.The method can be used for the determination of trace Cd in geochemical samples.