A four-column chromatographic protocol for V isotope analysis of high Ti/V geological materials

Abstract

Vanadium (V) isotope analysis of geological samples with high Ti/V is analytically challenging due to the formation of Ti-rich precipitates during digestion and Ti-induced interferences during purification and mass spectrometry. Here, a four-column chromatographic purification protocol is established for efficient V separation from Ti-rich matrices. Digestion in concentrated acids suppresses precipitate formation, and sequential column chromatography under strongly acidic conditions enables the effective removal of Fe and Ti using AG1-X8 and LN-B50-S resins. Residual matrix elements are further eliminated under weakly acidic conditions with AG50W-X12 and AG1-X8 resins. Systematic experiments employing variable Ti/V ratios and controlled sample loading were performed to constrain the practical loading capacity of the purification scheme. Quantitative V recovery higher than 99.9% and long-term external precision better than ±0.10‰ (2 SD) were achieved. High-precision δ⁵¹V data are reported for nine geological reference materials, demonstrating the robustness of the protocol for high Ti/V systems.