Measurement of arsenic compounds in water by HPLC-ICP-MS

This report provides a brief introduction to the application of high-pressure liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) to determine the concentration of various arsenic species in water samples. It describes the validation of this arsenic speciation method developed under the Laboratory Maintenance and Development Capability Programme to provide data on arsenic speciation in a range of challenging sample matrices to support BGS science projects and university collaborative research projects. The validation was carried out in two stages. Firstly, the chromatographic conditions for separating five arsenic species and coupling of the HPLC to the ICP-MS instrument for subsequent measurement of arsenic at mass 75 were optimised, together with establishing the stability of standards and reagents. Once the methodology had been optimised, validation data were obtained based on the method of Cheeseman and Wilson (Cheeseman & Wilson, 1989). The measurement of arsenobetaine (AB) and dimethylarsinous acid (DMA) by the proposed methodology provided good performance data with respect to certified values for the certified reference material NIES CRM 18 human urine. Performance data obtained for spiked low and high TDS solutions was generally within acceptance criteria outlined in the validation plan (Appendix 1) for all of the arsenic species.