High-resolution mass spectrometry for molybdenum speciation in sulfidic waters.

Author(s) Dang, D.Huy; Wang, W.; Evans, D.
Journal Talanta
Date Published 2020 Mar 01

High resolution electrospray ionization mass spectrometry (ESI-HRMS) was used to study the speciation of molybdenum in interaction with sulfide and chloride. While reactions between molybdate and sulfide lead to creation of four conventional thiomolybdate species (MoOS, MoOS, MoOS, MoS), chemical formula assignment of recorded mass spectra confirmed the presence of intermediate thiomolybdate compounds (MoOS, MoOS, MoOS, MoS, MoS) and thio-chloro-molybdate compounds (MoOCl, MoOSCl, MoOSCl, MoOSCl). Two of the intermediate thiomolybdate compounds were previously suggested theoretically, and this study provides analytical support for the existence of these compounds. Fast ESI-HRMS analysis has allowed us to conduct a highly-resolved short-term kinetic study of these reactions, and we suggest that the reactivity between molybdate and sulfide is more complex than previously thought, particularly during the first 24 h of interaction. Also, the solution composition will impact reaction pathways, and different outcomes found in the literature may arise from choices of ionic strength and pH adjusting agents in previous studies . The occurrence of the thio-chloro-molybdate species detected in this study should be implemented in future Mo speciation models to better assess Mo reactivity in sulfidic waters and reducing environments.

DOI 10.1016/j.talanta.2019.120585
ISSN 1873-3573
Citation Talanta. 2020;209:120585.