Hydride Generation-Based Purification Method for High-Precision Antimony Isotopic Analysis in Low-Concentration and Complex-Matrix Samples

Antimony (Sb) isotopes have emerged as a powerful tool for tracing Sb sources and understanding their geochemical behavior in different systems. However, accurate and precise determination of Sb isotopic compositions (δ123Sb) in natural samples remains a challenge, especially in low-concentration samples with complex matrices. In this study, we introduce a novel two-step purification method for high-precision Sb isotope analysis. In the first step, hydride generation (HG) is employed to effectively isolate Sb from major elements, followed by further purification with a thiol silica column. After optimization, two distinct HG purification modes were established: a flow mode for water samples and a no-flow mode for solid geological samples. Our method achieved complete Sb purification recovery with effective removal of matrix elements and the procedure blank was under the detection limits (<0.1 ng). Moreover, the HG purification process is rapid, requiring only 1 h for a 1 L water sample and 1.5 h for a 1 g geological sample. Application of this method to Sb standard solutions and geochemical reference samples yielded δ123Sb values in excellent agreement with the reference data, confirming that no isotopic fractionation occurred during the HG purification. Finally, we successfully applied this technique to a range of low-Sb environmental samples, including river, seawater, and sediments, demonstrating its effectiveness in accurate and precise Sb isotopic analysis. Overall, this novel method offers a rapid and efficient purification strategy for high-precision Sb isotopic analysis, thereby enhancing our ability to investigate Sb isotopic reservoirs associated with biogeochemical cycles.