Yankuang ceshi (Jul 2013)
Quantification of Cr in Natural Sparkling Mineral Waters by Inductively Coupled Plasma-Mass Spectrometry
Abstract
Natural sparkling mineral water contains high concentrations of HCO3- (about 1500 mg/L) and CO2(about 400 mg/L) and the concentration of Cr is equal to or lower than the detection limit of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Moreover, it is easy to form the polyatomic ion 40Ar12C, which interferes with the determination of 52Cr in the water by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Therefore, it is not possible to accurately quantify Cr in natural sparkling mineral water by ICP-MS. In this paper, a new method is described to quantify Cr in natural sparkling mineral water. The water is heated to 100℃ for 2 minutes, cooled to room temperature, and the acidity of the samples is adjusted to 5% (volume ratio) with nitric acid，which promotes HCO3- and H+ reactions to generate CO2 gas, thus being rapidly released. The interference of 40Ar12C on 52Cr is eliminated by this pretreatment of the natural sparkling mineral water, and the accurate determination of Cr in the water was conducted by ICP-MS. The detection limit of this method is 0.23 ng/mL. The results were satisfactory with the recoveries from 92.3% to 93.7%. This method is not only simple and practical, but can also be used to simultaneously and accurately quantify Ni, Cu, As, Cd and Pb in the water samples by ICP-MS. Its precision and accuracy meet the requirements of natural mineral water analysis.
