天青石中锶同位素组成测定——酸溶和碱熔样品分解方法的对比

Determination of Strontium Isotopic Composition in Celestite——Comparison of Sample Decomposition Using Acid Digestion and Alkali Fusion

利用酸溶法和碱熔法分解天青石样品,经过离子交换分离得到纯净的Sr,测定^(87)Sr/^(86)Sr同位素比值,实验结果表明两种样品分解方法得到的^(87)Sr/^(86)Sr同位素比值的偏差〈0．0001,证明在天青石锶同位素组成测定中,酸溶法和碱熔法都是可行的;但与碱熔法相比,酸溶法更简易并且利于本底值的控制。

Celestite samples were decomposed by both acid digestion and alkali fusion techniques. Strontium isotopic composition was determined by thermal ionization-mass spectrometry -after purification using cation-exchange resin. Isotopic dilution experiments were also carried out to quantify the strontium content after sample decomposition. Though large difference in strontium recovery exists between the two decomposition techniques, the measured ^87Sr/^86Sr ratios are identical with deviations of less than 0. 000 1. This suggests that both acid digestion and alkali fusion techniques are suitable for strontium isotopic composition measurement of celestite. Relative to alkali fusion techniques, the method of partial digestion of celestite using acids is simpler and easier in purification blank control.