钼同位素比值的双稀释剂测定方法研究

摘要

Techniques for high-precision measurement of Mo isotopic ratios using MC-ICP-MS have been developed, and the instrumental mass discrimination is corrected by double spike approaches. In this paper, the 100Mo/97Mo ratios of Fisher-Mo standard solution and double spike were calibrated by 104Pd/102Pd firstly, and then the calibrated 100Mo/97Mo ratio was employed for calibration of other Mo isotopic ratios. The external precision achieved over a period of 10 months is 0.035‰/amu at 95% confidence level, better than that of sample-standard bracketing. There is no difference in the Mo isotopic composition calculated by different calibration results (in the open university of UK and in the authors' laboratory), which indicates that the effect of different spans of time and instruments and the precision of 104Pd/102Pd can be neglected. The Mo isotopic compositions of 2 black shale samples obtained in this laboratory is in excellent agreement with that of the open university of UK, showing that the Mo isotopic data of the authors' laboratory are reliable.%本文报道了运用多接收器等离子体质谱测定Mo同位素组成的方法,测定过程中使用双稀释剂法校正仪器的质量分馏.Fisher-Mo标准溶液和双稀释剂的100Mo/97Mo使用Fisher-Pd标准溶液中的104pd/102pd标定,其他Mo同位素比值通过100Mo/97Mo标定；本文对运用双稀释剂技术进行Mo同位素测定的长期重现性进行了研究,结果表明,在95％的可信度范围内,Mo同位素比值测定的外部精度均不低于0.035％/amu,好于样品-标样交叉法；将经过化学纯化后的Fisher-Mo作为样品进行分析,使用本实验室和英国开放大学的标定结果分别进行计算,结果表明两个标定结果计算出的Mo同位素数据在误差范围内相同,说明不同的标定结果对Mo同位素数据的影响可以忽略不计,同时也说明104pd/102pd的精度对Mo同位素数据几乎没有影响;在本实验室和英国开放大学分别分析了2块黑色页岩的Mo同位素组成,两个实验室的结果在误差范围内一致,说明所建方法有效准确.