电感耦合等离子体质谱测定地质样品中Pb同位素比值

铅有 4个天然的同位素 ,由于放射衰变、宇宙的辐射及人类的活动 ,使 2 0 6Pb/2 0 4 Pb,2 0 7Pb/2 0 4 Pb及2 0 8Pb/2 0 4 Pb值在自然界中呈现相应的变化 ,而这种变化使得铅同位素成为一种有效的示踪手段和地质年代学研究的工具 ,同时在环境质量监控、放射性污染追踪及人类社会的变迁等方面有着广泛应用 .热电离质谱 (TIMS)分析技术对于大多数的同位素比值测定具有极高的精密度和准确度 ,但对于铅的测定由于难以获得一个高度浓缩且稳定不变的同位素作为内标进行质量偏移校正 1] ,使其测定的准确度受到影响 .Rehkamper等 2 ,3 ] 研究了…

Determination of Lead Isotope Ratios in Geological Samples by Inductively Coupled Plasma Mass Spectrometry

A simple and precise method for direct determination of molar ratio of 206Pb/ 204Pb, 207Pb/ 204Pb and 208Pb/ 204Pb by ICP-MS was developed. The data acquirement parameters of MS for Quadrupole setting time(QST), Dwell time(DT), Integrated time and number of sweeps were investigated in detail. The relative standard deviation(RSD) of different Pb isotope ratios were less than 0.32%n=5, ρ(Pb)=20 ng/mL]. The mass discrimination and dead time of detector was calibrated by using NIST981 solution. The mass bias factor(α) of 206Pb/ 204Pb, 207Pb/ 204Pb and 208Pb/ 204Pb were 0.002 5, 0.002 9 and 0.002 0, respectively. The dead time of detector was 7 ns. The proposed method has been applied to the analysis of geological standard reference materials containing AGV-1, BCR-2 and BHVO-2 .The relative error between this work and the recommend values or reported values was better than 0.73% and the relative standard deviation was better than 0.93%(n=5).