ABSTRACT
BACKGROUND: The electrochemical hydride generation technology, which uses electrolysis instead of chemical reagents to generate reducing species to achieve gaseous transformation and sample introduction of the tested elements, has received widespread attention in the field of atomic spectroscopy due to its simple, economical, and green characteristics. However, limited by the effective area of the electrode, the introduction efficiency and spectral signal of most elements (e.g., germanium) in practical applications are lower than traditional chemical hydride generation. RESULTS: In this paper, an efficient electrochemical hydride generation (EHG) method based on metal foam electrode for µg L-1 level germanium was constructed. Systematic electrochemical and spectral tests showed that the low charge transfer resistance and the high electrochemical activity of nickel-based foam electrodes jointly promoted the efficient electroreduction of Ge(IV). Besides, the porous network structure of the metal foam material improves the contact probability of reactants while reducing the gas-evolution effect caused by bubble accumulation. Interestingly, adequate reaction sites are crucial for the conversion of germanium, but large foam electrodes are not always compatible with analytical performance. After coupling atomic fluorescence spectroscopy, this new electrolysis method has been proven to be suitable for efficient conversion and quantitative detection of Ge over a wide concentration range (5-150 µg L-1). SIGNIFICANCE: Our proposal to improve the electrosynthesis efficiency of germanane (GeH4) by using metal foam electrode is extremely effective for the detection of trace or ultra-trace germanium. The exploration of electrode material, structure, and especially effective area will also provide ideas for the establishment of highly sensitive analysis methods in the future.
ABSTRACT
In this study we firstly report a new electrolytic cold vapor generation system for mercury determination on Pt/Ti cathode in the presence of organic acid catholyte. Comparing with the traditional inorganic acid, formic acid increased the signal intensity of Hg vapor from electrolytic generation on Pt cathode and reduced the impact of cathode erosion on the stability of signal intensity. Moreover, formic acid has better interference tolerance. The introduction location for carrier gas is probably the most important factor that influences the signal intensity of Hg from electrolytic vapor generation. The effects of the electrolytic conditions and interference ions on the ECVG have been studied. Under the optimized conditions, the detection limit (3 sigma) of Hg (II) in aqueous solutions is 1.4 ng L(-1); a relative standard deviation of 2.3% for 1 microg L(-1) Hg was obtained. The accuracy of this method was verified by the determination of mercury in the certified reference materials. This system has been applied satisfactorily to the determination of Hg in Traditional Chinese Medicines samples.
