Determination of chromium species in water samples by liquid chromatography-inductively coupled plasma-dynamic reaction cell-mass spectrometry

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 C-8 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 (ArC+)-Ar-40-C-12, (ClOH+)-Cl-35-O-16, (ArCH+)-Ar-40-C-12 and (ClO+)-Cl-37-O-16 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.