Determination of Cr, Cu, Cd and Pb in Soil Samples by Inductively Coupled Plasma-Mass Spectrometry for an Investigation of Heavy Metal Pollution

The present methods for the determination of heavy metals in soil by Inductively Coupled Plasma-Mass Spectrometry(ICP-MS) have many disadvantages including an inappropriate decomposition process and the parameters of instruments requiring optimization.To address this inadequacy, soil samples for an investigation of heavy metal pollution have been characterized by complex matrices, large weights and different properties of measured elements.Combining acid decomposition on an electric heating plate with ICP-MS, the key to determination of four kinds of main heavy metal pollutants, Cr, Cu, Cd and Pb, in soil were explored and are presented in this study.The results show that the samples can be decomposed completely by a mixture of nitric acid, hydrochloric acid, hydrofluoric acid, and sulfuric acid(50%).The matrix effect is reduced effectively by the work curve and the mass spectrum interference is reduced effectively by both adopting collision/reaction cell technology and by mathematical correction.Integration time and repeated times of ICP-MS have significant influences on testing results of trace Cd, so the optimal parameters of them are 0.4s and 3 times, respectively.The detection limits of this method for Cr, Cu, Cd and Pb are 1.74, 0.89, 0.015 and 0.08μg/g, respectively.This study provides a rapid and accurate method for determining heavy metals in soil.