Measurement of Pb isotopes for geological samples by MC-ICP-MS coupled with an extraction resin column preconcentration method

Lead isotopic variations provide crucial insights into geochemical reservoirs, environmental sources, and geological ages. To obtain precise Pb isotope data by MC-ICP-MS, we develop a simple and efficient separation procedure using trialkyl amine (N235) resin. Batch experiments show that N235 strongly adsorbs Pb in 0.4 mol L^-1 HBr, weakly in HCl, and not at all in HNO₃ media. Specifically, the optimized column procedure achieved high Pb recovery (94.5%) and eluted Pb in 0.5 mol L^-1 HNO₃, allowing direct measurement without evaporation, thereby reducing procedural blanks. The method was validated with ten reference materials (GSR-1, GSR-2, GSR-3, GSR-7, GSP-2, BHVO-2, JA-2, JG-2, JB-2, and JA-1a). Measured ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios agreed with published values within uncertainty, with external reproducibility better than 0.05% (RSD). Owing to its simplicity, high recovery, low blank, and low cost, this method offers a practical pretreatment strategy for high-precision Pb isotope analysis in diverse geological samples.