Study on the Conditions for Enrichment and Purification of Os by Micro-distillation and Its Application in NTIMS Measurements

BACKGROUND Micro-distillation is an important chemical pretreatment technology for the enrichment and purification of Os. It is particularly important to improve Os recovery by optimizing the micro-distillation experimental conditions to ensure the accurate measurement of Os by NTIMS. The micro-distillation temperature, absorbing solution volume, and reaction time have significant influence on the recovery of Os. However, the optimum experimental conditions for micro-distillation are not clear, thus resulting in unstable Os recovery, affecting NTIMS measurement accuracy, and easily resulting in increased Re-Os dating error. OBJECTIVES To evaluate the influence of different experimental conditions on the yield of Os during the micro-distillation for improving the recovery of Os, ensuring the intensity and stability of the Os measurement signal by NTIMS. METHODS A self-made Os-containing solution was chosen as the research object and ICP-MS was used as the measurement method. The element Ir was used as the internal standard to monitor the Os signal, and the Os recovery was calculated by the sample signal count. RESULTS The results show that the maximum recovery of Os was obtained when the HBr solution was evaporated at 120℃ for 15 min, the micro-distillation temperature was 80℃, the HBr absorption solution was 15 μL, and the micro-distillation reaction time was 2 h. The Os recoveries were 80%-90% under the optimum experimental condition. CONCLUSIONS Os recovery under the optimum micro-distillation experimental conditions satisfies the measurement requirements of NTIMS, especially for pg level geological samples. It also increases the Os signal intensity and improves the efficiency of experiments.