Dielectric Barrier Discharge for High Efficiency Plasma-Chemical Vapor Generation of Cadmium

Abstract

A novel approach for Cd vapor generation was developed on the basis of a plasma-assisted chemical process. The generated Cd vapor was subsequently measured by atomic fluorescence spectrometry. Dissolved Cd species were readily converted into volatile species by reaction with hydrogen in a coaxial thin-film dielectric barrier discharge (DBD) plasma reactor. Both atomic and molecular Cd species were produced when a solution containing Cd(2+) was exposed to hydrogen-containing DBD plasma. Fast and efficient vapor generation of Cd was achieved simply in plain (neutral) water medium. Optimal conditions for the DBD-plasma Cd vapor generator were identified. The performance of this thin-film DBD plasma-chemical vapor generation (CVG) was evaluated through comparison with that arising from the conventional HCl-KBH4 system. The vapor generation efficiency of the proposed method (He-DBD) was found to be superior to the conventional CVG approach. Under the optimized conditions, the detection limits of Cd were found to be from 0.03 ng mL(-1) (Ar-DBD) to 0.008 ng mL(-1) (He-DBD) with a heated quartz tube atomizer (QTA); good repeatability (relative standard deviation (RSD) = 1.4%, n = 5) was obtained for a 1 ng mL(-1) standard. The new thin-film DBD plasma-CVG provides several additional advantages including simple setup, easy coupling with flow injection, low power consumption (≤18 W), cost-effectiveness, and long operation lifetime. The accuracy of the proposed method was validated through analysis of cadmium in reference material of simulated natural water sample GBW(E)080402 and rice reference material GBW10045. The concentration of cadmium determined by the present method agreed well with the reference values.