title: Matrix effects of calcium on high-precision sulfur isotope measurement by multiple-collector inductively coupled plasma mass spectrometry.
abstract: Multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has been successfully applied in the rapid and high-precision measurement for sulfur isotope ratios in recent years. During the measurement, the presence of matrix elements would affect the instrumental mass bias for sulfur and these matrix-induced effects have aroused a lot of researchers' interest. However, these studies have placed more weight on highlighting the necessity for their proposed correction protocols (e.g., chemical purification and matrix-matching) while less attention on the key property of the matrix element gives rise to the matrix effects. In this study, four groups of sulfate solutions, which have different concentrations of sulfur (0.05-0.60mM) but a constant sequence of atomic calcium/sulfur ratios (0.1-50), are investigated under wet (solution) and dry (desolvation) plasma conditions to make a detailed evaluation on the matrix effects from calcium on sulfur isotope measurement. Based on a series of comparative analyses, we indicated that, the matrix effects of calcium on both measured sulfur isotope ratios and detected (32)S signal intensities are dependent mainly on the absolute calcium concentration rather than its relative concentration ratio to sulfur (i.e., atomic calcium/sulfur ratio). Also, for the same group of samples, the matrix effects of calcium under dry plasma condition are much more significant than that of wet plasma. This research affords the opportunity to realize direct and relatively precise sulfur isotope measurement for evaporite gypsum, and further provides some suggestions with regard to sulfur isotope analytical protocols for sedimentary pore water.
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China; Collaborative Innovation Center of South China Sea Studies, Nanjing University, Nanjing 210093, PR China.
authors.forename: Chenhui
authors.initials: C
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China; Collaborative Innovation Center of South China Sea Studies, Nanjing University, Nanjing 210093, PR China.
authors.forename: Xiao-Peng
authors.initials: XP
authors.lastname: Bian
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China; Beijing SHRIMP Center, Institute of Geology Chinese Academy of Geological Sciences, Beijing 102206, PR China; Collaborative Innovation Center of South China Sea Studies, Nanjing University, Nanjing 210093, PR China. Electronic address: yangtao@nju.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China; Thermo Fisher Scientific China Co., Ltd, Guangzhou 510030, PR China.
authors.forename: An-Jun
authors.initials: AJ
authors.lastname: Lin
authors.affiliation: State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, PR China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, PR China; Faculty of Earth Resources and Collaborative Innovation Center for Scarce and Strategic Mineral Resources, China University of Geosciences, Wuhan 430074, PR China.
authors.forename: Shao-Yong
authors.initials: SY
authors.lastname: Jiang
keywords: Calcium concentration; MC-ICP-MS; Matrix effects; Sulfur isotope