Simultaneous Determination Of Tungstates, Thiotungstates, And Polytungstates In Natural Waters By Reverse Phase Ion Pair Chromatography Coupled With ICP-MS

Abstract

: Polymeric tungstates exhibit different toxicities and mobilities when compared to those of monomeric tungstates. However, there is limited information on the occurrence of polytungstates in natural waters due to the lack of a reliable analytical approach for the determination of aqueous polytungstates. In this study, we conducted a simultaneous analysis of monomeric and polymeric tungsten species in natural water using reverse-phase ion pair chromatography coupled with inductively coupled plasma mass spectrometry (RP-IPC-ICP-MS). Polytungstates and five monotungstates, including tungstate as well as mono, di, tri, and tetrathiotungstate, were chromatographically separated within 35 min of using ethanol (12 - 48% gradient) as the mobile phase. The detection limit of polytungstates was 1.50 µg/L. Although common for the analsis of metals, experimental studies based on electrospray ionization - high resolution mass spectrometry (ESI-HRMS) have indicated that samples containing polytungstates should not be acidified, as it could result in the transformation of monotungstates to artifact polytungstates. Overall, our study offers an effective method for the analysis of various tungsten species, especially polytungstates, at environmentally relevant concentrations.