Optimisation of ICPMS collision/reaction cell conditions for the simultaneous removal of argon based interferences of arsenic and selenium in water samples

The optimisation of ICPMS collision/reaction cell conditions for the simultaneous analysis of arsenic and selenium is described. A mixture of 3.8 mL min^?1 of H₂ and 0.5 mL min^?1 of He was found to be suitable for the removal of both ArAr⁺ and ArCl⁺ interferences. Detection limits down to 30 ng (element) L^?1 in total analysis, and between 81 and 230 ng (element) L^?1 in speciation analysis were achieved in chloride matrix (1 g L^?1 NaCl). After validation, the method was applied to commercially available mineral waters.