ELIMINATION OF THE ARGON CHLORIDE INTERFERENCE ON ARSENIC SPECIATION IN INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY USING ION CHROMATOGRAPHY

Ion chromatography has been combined with inductively coupled plasma mass spectrometry for the speciation of arsenic compounds commonly found in urine. Ion chromatography was used to eliminate or reduce the mass spectral interference formed from chloride, namely argon chloride, by resolving chloride chromatographically from the arsenic compounds. A 20-fold dilution of the urine samples was necessary in order to avoid column overloading from chloride and subsequent argon chloride interference. Detection limits in urine of 3.4 p.p.b. AsIII, 4.2 p.p.b. Asv and 7 p.p.b. dimethylarsinic acid were obtained. Three commercially available freeze-dried urine standards were analysed using the standard additions method. Good agreement was obtained for total arsenic content, which was calculated from the sum of the species with accepted arsenic concentration. The relative standard deviation of peak height for each of the species was approximately 5% in urine.