A Study on Memory Effects in Lithium and Boron Isotope Analysis Using MC-ICP-MS

Lithium (Li) and boron (B) isotopes are excellent tracers in geological processes. In order to study and eliminate the memory effects of lithium and boron element in isotopic measurements using MC-ICP-MS, different background rinsing protocols were designed with reference to previous research. The δ⁷Li and δ¹¹B values of different types of reference materials were tested to evaluate the long-term reproducibility of the measurements using designated rinsing protocols for at least six months. The results show that using only 0.3% NaCl solution to clean the background for 60s can significantly reduce the lithium background signal and ensure the ⁷Li background signal is less than 5mV within 24h. The long-term external precision of δ⁷Li values for Alfa Li, an in-house standard, was 0.13‰ (2SD, n=73). Rinsing solutions, such as NAF and NH₃·H₂O could not significantly reduce the boron background of the instrument. However, the flexible blank subtracting method was used for precise determination of δ¹¹B values. The long-term external precision of δ¹¹B values for Alfa B was 0.19‰ (2SD, n=60). The average δ⁷Li and δ¹¹B values of different types of reference materials were tested using these rinsing protocols, and the results were well consistent with reported data, supporting the applicability of the conclusions. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202310260167.