Multielemental determination of arsenic, selenium and chromium(VI) species in water by high-performance liquid chromatography-inductively coupled plasma mass spectrometry

A new method for the simultaneous chromatographic separation and determination of arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, selenite, selenate and hexavalent chromium in water is presented. Speciation was achieved by on-line coupling of anion-exchange LC and inductively coupled plasma mass spectrometry (ICP-MS). Optimisation of the chromatographic conditions led to baseline separation of the seven species in 14 min using gradient elution with NH4NO3 20 mM, pH 8.7-NH4NO3 60 mM, pH 8.7 as mobile phase. Detection limits are in the range 40-60 ng 1(-1) for arsenic species, around 130 ng l(-1) for Cr(VI), and higher for Se(IV) and Se(VI) (1.2 and 1.4 mug l(-1) respectively). The method showed good accuracy and repeatability, and no interference of chloride on (75)AS, Se-77 or Cr-53 was observed. The developed method was applied to the analysis of several environmental surface water samples. (C) 2001 Elsevier Science B.V. All rights reserved.