Chromatographic separation of gallium for precise isotope measurement by MC-ICP-MS

Gallium (Ga) has special physiochemical characteristics and important economic value, thus is of great interest in many research aspects. Over the past decades, significant advancements about Ga geochemistry have been achieved... [ view full abstract ]

Gallium (Ga) has special physiochemical characteristics and important economic value, thus is of great interest in many research aspects. Over the past decades, significant advancements about Ga geochemistry have been achieved based mainly on the analysis of Ga concentration and species. These studies have demonstrated that the species, the coordination and lattice of Ga could change under different physical-chemical conditions, or be modified in many physiochemical processes. In addition, Ga would also behavior differently in variable biological processes. Thus, Ga isotopes are beneficial for studies of its geochemical behavior, and may have numerous potential applications. However, without an effective and reliable method for separation of Ga from matrix, Ga isotopes have been rarely reported.
We developed a chromatographic method for purifying Ga from geological (biological) samples for precise analysis of Ga isotopic composition on MC-ICP-MS. The isotopic measurements were performed on the Nu Plasma II MC-ICP-MS (Nu Instruments Ltd., UK) or Neptune Plus MC-ICP-MS (Thermo Finnigan®., Germany). Our Ga purification method has Ga recovery of 99.8±0.8% (2SD，n=23) and no fractionation is introduced. Long-term measurement gave reliable δ71/69Ga analysis with precision 0.05‰ (2SD). The δ71/69Ga of two basalt and one Ga standard solution are 0.11±0.02‰ (2SD，n=9), 0.08±0.02‰(SD, n=10) and 1.74±0.05‰ (2SD，n=100), respectively, demonstrating the potential exploration and applications of Ga isotopes in geochemistry, cosmochemistry, oceanography and environmental research.