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

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journal contribution
posted on 16.04.2013, 00:00 by Zhenli Zhu, Qingju, Wu, Zhifu Liu, Lu Liu, Hongtao Zheng, Shenghong Hu
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 Cd2+ 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.