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

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 (CrIII and CrVI) 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 CrIII and CrVI 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.