Chromatographic purification of antimony for accurate isotope analysis by MC-ICP-MS
A two-step method for purifying antimony (Sb) from geological samples for accurate measurement of Sb isotopic composition using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) was developed. Sb was separated from the matrix using two successive chromatographic columns loaded with AG 1-X4 and AG 50W-X8 resin, respectively. The separation method was calibrated using geological samples by assessing the extraction yield and the reproducibility of the measured isotopic composition, and resulted in a relatively low procedure blank and better recovery (98.7% ± 5.6%, n = 8, 2SD) compared to previous studies. The validation of the whole protocol, together with instrumental analysis, was confirmed by the investigation of the matrix effect and the result of a standard addition experiment. A combined sample-standard bracketing and external normalization (SSB-EN) method using cadmium (Cd) as an internal element was used for mass bias correction, which gave a reproducibility better than 0.04‰ (2SD). A variation of 0.29‰ of the δ123Sb value (relative to the NIST SRM 3102a standard) was observed in artificial and geological samples, implying the potential application of Sb isotopes in various environments.