ELSEVIER ANALmcA zyxwvutsrqpo CHIMICA zyxwvutsrqponm AC’IA Analytica Cbimica Acta 314 (1995) 183-192 On-line preconcentration of seleniumt IV) and selenium( VI) in aqueous matrices followed by liquid chromatography-inductively coupled plasma mass spectrometry determination Yong Cai a, Merck Cabafias b, Jo& L. Ferrhdez-Turiel b, Manoli Abalos b, Josep M. Bayona a9 * a Environmental Chemishy Department, CID-CSIC, Jordi Girona, 18-26, E-08034 Barcelona, Spain b Institute of Earth Sciences “Jaume Almera”, CSIC, Marti i Fray&s, s/n, E-08028 Barcelona, Spain Received 30 September 1994; revised 24 April 1995; accepted 15 May 1995 Abstract A study was carried out for the determination of selenite and selenate from water matrices using ion-pairing reversed-phase or anion exchange liquid chromatography followed by determination with inductively coupled plasma mass spectrometry (LC-ICP-MS), which used conventional pneumatic nebulization as sample introduction technique. The detection limits and background levels for the anion exchange chromatography were lower than those for the ion-pairing separation method. Based on the optimum conditions obtained with a 25 /*l sample injection loop, a preconcentration column was coupled on-line with the anion exchange LC-ICP-MS system. The capability of this simple on-line preconcentration procedure was demonstrated for the analysis of various water matrices spiked with selenite and selenate including high salt-containing water, river, tap, and well water samples. The detection limits (3~) obtained by preconcentra- tion of 2-10 ml of the high salt-containing water and other aqueous matrices were 0.16-0.42 and 0.08-0.19 pg 1-l of Se for selenite and selenate, respectively. These relative detection limits were ca. two orders of magnitude better than those obtained with a 25 ~1 sample loop. Keywords: Inductively coupled plasma-mass spectrometry; Liquid chromatography; Preconcentration; Selenium 1. Introduction Recently, there has been increasing interest in trace determination of selenium because of its dual role, as an essential nutrient at low concentrations, or a toxin (selenosis) at an intake of 5 mg Se kg-’ (in mammals) [l-3]. The narrow concentration range between the two opposite effects (0.1-4.0 mg kg-’ * Corresponding author. in plants), requires accurate and precise knowledge of the selenium species present in the environment [4,5]. It appears that natural sources such as parent materials (sedimentary rocks and shale) contribute to the formation of soils with high selenium content (up to 1200 mg g-’ in Ireland) or waterways (1400 mg 1-l in California). Furthermore, anthropogenic sources cannot be underestimated due to a variety of industrial uses [6]. Detailed information about the availability and mobility of selenium in the environment and its 0003-2670/95/$09.50 0 1995 Elsevier Science B.V. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFE All rights reserved SSDI 0003-2670(95)00274-X