Determination of Cadmium by Flow Injection Isotope Dilution Inductively Coupled Plasma Mass Spectrometry With Vapour Generation Sample Introduction

Abstract

A simple and inexpensive laboratory-built vapour generator was used with isotope dilution-ICP-MS for the determination of cadmium in several reference materials. The application of vapour generation-ICP-MS alleviated the spectroscopic interferences in cadmium determination encountered when a conventional pneumatic nebulizer was used for sample introduction. The sensitivity, detection limit and repeatability of the flow injection-ICP-MS system with a vapour generator were comparable to those of ICP-MS analysis with conventional pneumatic nebulization. The repeatability of the peak areas and isotope ratio determinations of seven consecutive injections of a 1 ng ml -1 cadmium solution was 3.5 and 1.9%, respectively. The method has a detection limit of 0.026 ng ml -1 for cadmium. The method was applied to the determination of cadmium in NIST SRM 2704 and National Research Council of Canada (NRCC) BCCS-1 and PACS-1 sediment reference materials, NIST SRM 2670 Toxic Metals in Freeze-Dried Urine and several water reference materials. The concentrations of cadmium in the reference materials were quantified by the isotope dilution method. The precision between sample replicates was better than 10% and the analysis results were within 5% of the certified values for most of the determinations.