钾同位素的高效分离及 MC-ICP-MS 高精确测定

Potassium (K) is widely applied in earth sciences, biological sciences, environmental sciences and other fields. This study presents a method for high-efficient purification for a variety of samples and high-precision determination for K isotopes by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Potassium in digested samples was separated by cation-exchange chromatography with AG 50W-X8 resin, and was eluted by 0. 5 mol / L HNO₃. It’s achieved a high recovery of K with the yield of >99. 9% and negligible blank (~ 10 ng K). Nevertheless, for samples with high contents of matrix elements (Li、 Na、 Mg、 Al、 V、 Cr、 Ca), two-step purification procedure is suggested. The purified samples were analysed by MC-ICP-MS using " cold plasma-low resolution" . The values of δ⁴¹K of international standards (rock、coal and biology) are consistent with literature, and the long-term precision is better than 0. 06‰ with good reproducibility.