Cold vapor generation of Zn based on dielectric barrier discharge induced plasma chemical process for the determination of water samples by atomic fluorescence spectrometry

摘要

A new plasma chemical vapor generation (plasma- CVG) method for Zn was developed by dielectric barrier discharge (DBD). The dissolved Zn ions was readily converted to volatile species by DBD plasma in the presence of hydrogen and then, the generated Zn vapor, Zn~0, was detected by cold vapor atomic fluorescence spectrometry (AFS). It eliminated the use of unstable tetrahydroborate-reducing reagent and high-purity acids. The operating conditions for the DBD plasma-CVG system were optimized for the efficient vapor generation of Zn. In addition, possible interferences from coexisting ions on the plasma-CVG of Zn were also examined. No appreciable matrix interference was found from most of the examined ions at concentration of 1 mg L~(-1). However, severe depression of the Zn vapor generation efficiency was observed in the presence of ions at 10 mg L~(-1). Under the optimal conditions, the limit of detection (LOD) was calculated to be 0.2 μg L~(-1); good repeatability (relative standard deviation (RSD)=2.6 %, n=11) was obtained for a 20 Zn μg L~(-1) standard. The accuracy of the proposed method was validated though analysis of Zn in reference material of simulated natural water sample GSB07-1184-2000 and the determined result was in good agreement with the reference value. The proposed method has also been successfully applied to the determination of Zn in Changjiang River water, Wuhan East Lake water, and Wuhan tap water samples. It provides an alternative green vapor generation method for Zn.