The use of 1-phenyl-3-methyl-4-benzoyl-5-pyrazone as chemical modifier for low-temperature electrothermal vaporization for separation and determination of Cr(III) and Cr(VI) by ICP-MS

Based on thermal stability and volatility of 1-phenyl-3-methyl-4-benzoyl-5-pyrazone (PMBP) chelate, a novel method was described for the determination of Cr(III) and Cr(VI) by low-temperature electrothermal vaporization (LETV) combined with inductively coupled plasma mass spectrometry (ICP-MS). It was found that Cr(III) could be rapidly formed in a graphite furnace, and quantitatively vaporized into ICP at a relatively low temperature of 1000 degrees C with the use of PMBP as a chemical modifier, while Cr(VI) was retained in the graphite tube. Thus, the separation of Cr(III) and Cr(VI) could be realized. The main factors affecting the formation and vaporization of Cr(III)-PMBP chelate were investigated in detail. Under the optimized conditions, the detection limit of Cr(III) for this method was 0.031 ng mL(-1) and the relative standard deviation (RSD) for 1.0 ng mL(-1) Cr(III) was 5.3% (n=9, v=10 mu L). The linear range of calibration curve spanned three orders of magnitude. The proposed method was applied to the determination of Cr(III) and Cr(VI) in water samples with satisfactory results. (C) 2010 Elsevier B.V. All rights reserved.