Abstract:This study demonstrates an analytical method for the high spatial resolution (20 μm) and high-precision determination of antimony (Sb) isotope composition in stibnite, using femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS). The potential matrix effect-inducing elements in Sb isotope composition measurements exhibit extremely low concentrations in two newly introduced natural stibnite reference materials, DC and BJS, rendering their impact virtually negligible during fs-LA-MC-ICP-MS analysis. Through reciprocal correction of DC and BJS, consistent results were achieved, aligning with those obtained by SN-MC-ICP-MS, indicating an absence of discernible matrix effects between the two samples. A comprehensive assessment was conducted to evaluate the contribution of the Sn standard solution to enhance the external precision of measurements. The 2SD of δ123Sb mean values increased by 0.02‰ to 0.04‰. Adjusting the laser ablation spot size (5μm-80μm) to control signal intensity, we investigated the deviation in δ123Sb caused by mismatched signal intensities between the sample and the reference material. The matching range of signal intensity between the reference sample and the test sample was within -40% to 140%, ensuring satisfactory precision. Additionally, once the signal intensity of 121Sb exceeded 15V, the internal precision of the 123Sb/121Sb ratio no longer exhibited a significant decline. Measurements of DC and BJS were conducted using fs-LA-MC-ICP-MS, coupled with SN-MC-ICP-MS, backscattered electron maps (BSE) and elemental compositions, confirming the accuracy of this method and the homogeneity of the two potential reference materials.