Rapid speciation and determination of vanadium compounds using ion-pair reversed-phase ultra-high-performance liquid chromatography inductively coupled plasma-sector field mass spectrometry

• A method for baseline separation of vanadyl and vanadate ions in less than a minute was developed.
• Detection limits for vanadyl and vanadate were obtained in the low ng L−1 range.
• Linear calibrations across several orders of magnitude (50 ng L−1–100 μg L−1) were obtained.
• The method of retention was elucidated through EDTA, pH, and ion pairing agent experiments.
• The optimized method was applied to determine vanadyl and vanadate in lake water.

Environmental vanadium contamination is a potential concern to public health, as evidenced by its place on the U.S. Environmental Protection Agency Drinking Water Contaminant Candidate List as a priority contaminant. Vanadium toxicity varies significantly between different oxidation states; therefore, it is crucial to be able to monitor the speciation of vanadium in environmental samples. In this study, a novel method is described that utilizes ion-pair reversed-phase ultra-high-performance liquid chromatography with inductively coupled plasma-sector field mass spectrometry (IP-RP-UHPLC-ICP-SFMS) to separate vanadyl and vanadate ions and resolve a major polyatomic spectral interference (35Cl16O+) in less than a minute. Detection limits were obtained in the low ng L−1 (part per trillion) range with linear calibrations across several orders of magnitude (50 ng L−1–100 μg L−1). The mechanism of chromatographic retention was elucidated through investigation of the role of ethylenediaminetetraacetic acid, tetrabutylammonium ion and pH on elution. The optimized method was then applied to the speciation of vanadium in local lake water samples.