Abstract

An inductively coupled plasma-mass spectrometer (ICP-MS) equipped with a dynamic reaction cell (DRC) was used as a liquid chromatographic detector for the determination of chromium species. In this study, ionic chromium species (Cr^III and Cr^VI) were separated by reversed-phase liquid chromatography (LC) with a C₈ column as the stationary phase and 0.6 mmol l⁻¹ EDTA, 2 mmol l⁻¹ tetrabutylammonium phosphate and 2% v/v methanol solution (pH 6.9) as the mobile phase. The potentially interfering ⁴⁰Ar¹²C⁺, ³⁵Cl¹⁶OH⁺, ⁴⁰Ar¹²CH⁺ and ³⁷Cl¹⁶O⁺ at the chromium masses m/z 52 and 53 were reduced in intensity by approximately three orders of magnitude by using 0.65 ml min⁻¹ NH₃ as reaction cell gas in the DRC. Effluent from the LC column was delivered to the nebulization system and the ICP-MS for the determination of chromium. The repeatability of the peak area was better than 2% at m/z 52. The limits of detection for Cr^III and Cr^VI were 0.063 and 0.061 ng ml⁻¹ Cr at m/z 52, respectively, based on peak height. The concentrations of chromium species have been determined in several water samples collected from Kaohsiung area. The recovery was in the range of 90–110% for all the determinations.