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.