Speciation of arsenic compounds by ion chromatography with inductively coupled plasma mass spectrometry detection utilizing hydride generation with a membrane separator

Ion chromatography (IC) was used to speciate four of the environmentally significant, toxic forms of arsenic: arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid Hydride generation (HG) was used to convert the species to their respective hydrides, These hydride species mere detected with ICP-MS. The gas-liquid separator for the HG unit was based on microporous PTFE tubing. Two novel features which reduce noise are incorporated into the membrane-based HG unit: firstly, gas is added to the liquid stream prior to entering the membrane, and secondly, the flow of carrier gas through the gas-liquid separator forms a 'feedback' loop, Absolute detection limits based on 3.14 sigma from 7 replicates for the four arsenic species listed above were 0.6, 3.1, 1.1, and 0.7 pg, respectively, The overall IC-HG-ICP-MS system produced RSD values of 1-6% over 30 min and 2-6% over a week. for the four compounds, Two saline reference materials, NASS-4 and SLEW-2 (National Research Council of Canada), were analysed to determine concentrations of the fear arsenic species, and the sum of the arsenic concentration was compared with-the certified total arsenic value for each of the reference materials.