HAc溶解碳酸盐岩测定^(87)Sr/^(86)Sr值实验方法研究

Determination of ^(87)Sr/^(86)Sr Abundance Ratio in Carbonate Mineral After Dissolution with HAc

传统的碳酸盐岩的Sr同位素比值测定因为采用HCl溶样 ,往往导致非碳酸盐组分的溶解 ,引起测定值偏高 ,采用HAc溶样可以防止样品中非碳酸盐组分的溶解 ,同时也避免过多的杂质离子进入溶解液 ,从而使87Sr/86Sr测定值趋于准确和可靠 ;通过2.5mol/LHAc溶解碳酸盐矿样和4.0mol/LHCl溶解残渣样的最后质谱测定的 87Sr/86Sr值比较 ,证实碳酸盐岩中非碳酸盐组分的 87Sr/86Sr值较碳酸盐组分高。

The 87Sr/86Sr abundance ratio in carbonate rock is usually higher than its true value when traditional HCl is used for dissolving the rock sample. The key problem is that HCl can dissolve not only the carbonate but also the non _ carbonate compositions. The use of HAc for dissolving the rock sample was proposed. The result obtained for 87Sr/86Sr abundance ratio in Reference Standard(NBS987) with the proposed method was 0.710, which agreed quite well with the certified value. The RSD(n=10) was 0.018%. Experimental results also showed that the 87Sr/86Sr abundance ratio in the non-carbonate composition was generally higher than that in carbonate composition.