Abstract

Ion chromatography (IC) with conductivity detection (ConD) was coupled on-line with inductively coupled plasma-mass spectrometry (ICP-MS) for the purpose of multielement speciation in drinking water. The system allows for the determination of two disinfection by-products (bromate and iodate), their precursors (bromide and iodide), two suspect carcinogenic substances that occur naturally in drinking water (arsenite and arsenate) and three common matrix anions (chloride, nitrate and sulfate). Detection limits, achieved via the direct injection of 100 µL samples, were adequate for the analysis of water intended for human consumption. ICP-MS signal stability and reduced spectroscopic interferences were observed with the use of a membrane suppressor. The IC-ConD-ICP-MS method was used for the analysis of a series of drinking water and spiked drinking water samples. In all samples analysed, bromate and arsenic levels were below the maximum levels set by the US Environmental Protection Agency and the European Commission. Average spike recoveries [±RSD (%)] were 101 ± 1.5% for bromate, 96 ± 17% for bromide, 98 ± 2.8% for arsenic, 98 ± 1.9% for iodate, 91 ± 5% for iodide, 87 ± 5.5% for chloride, 96 ± 1.1% for nitrate and 95 ± 1.8% for sulfate. The method was also used to monitor bromate removal from drinking water following filtration through a domestic water purification unit.