扇形磁场电感耦合等离子体质谱法测定硫同位素组成

Measurement of Sulfur Isotopic Composition by Sector Field Inductively Coupled Plasma Mass Spectrometry

在中分辨模式(m/Δm=4000)下,利用扇形磁场电感耦合等离子体质谱仪(SF-ICP-MS)建立了精确测定硫同位素组成的方法,对ICP离子源、光学透镜系统、数据获取参数(扫描时间、扫描次数、积分窗口等)以及浓度效应进行了系统优化和评估,并用"标准-样品"交叉法校正仪器自身的质量歧视。在此基础上,在不同日期重复测定了GBW04414和GBW04415硫同位素参考物质的δ34SV-CDT,分别为"0.01‰±0.31‰和22.15‰±0.42‰,误差<±0.06‰,精密度<±0.5‰(n=10),达到了目前同类方法所报道的最高水平。同时,对瓶装矿泉水、雨水和河水等天然水样中δ34S进行了测定,测定精密度为±0.19‰～±0.58‰,与同位素参考物质的测定精密度相近。因此,本方法可用于精确测定天然水样中S同位素组成。

A precise method was developed for the determination of sulfur isotopic composition by sector field systematically, including the ion source, ion optical system, data acquisition parameters （i. e. scan time, scan numbers and integration window ） and the effect of sulfur concentration. The instrumental mass discrimination was corrected using standard-sample bracketing. The δ^34 SV.CDT of sulfur isotopic reference materials GBW04414 and GBW04415 was measured in different days, the measurement values were -0.01%o ＋0.31% and 22.15%±0.42%, respectively. The results showed that this method had a high accuracy （ error 〈±0.06%） and good precision （repeatability 〈＋0.5%, n = 10） in the determination of sulfur isotopic composition. Meanwhile, the proposed procedure was adopted to determine sulfur isotopic composition in some natural water samples （ bottled mineral water, rain water and river water）, the measurement precision was ＋0.19% to_＋0.58%, similar to that of the isotopic reference materials. The proposed method was suitable for the determining the sulfur isotopic composition of natural water samples precisely.