• Yanqin Zi

      Articles written in Journal of Chemical Sciences

    • Microdetermination of human serum albumin by differential pulse voltammetry at a L-cysteine modified silver electrode

      Liyuan Lu Yanqin Zi Hongling Wang

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      A simple and highly sensitive electrochemical method for the determination of human serum albumin (HSA) using differential pulse voltammetry (DPV), based on a silver electrode modified with a self-assembled monolayer of L-cysteine, was developed. L-cysteine can be modified onto a silver electrode by covalent bonding through the sulfur to give stable and long-lived chemical electrodes. This electrode showed good sensitivity, selectivity, reproducibility and time stability in the determination of trace amounts of HSA by DPV technique. The detection limit can be as low as $4 \times 10^{-17}$ mol/L. The optimum conditions for the determination were carefully investigated. This method had been applied to the determination of HSA in human serum samples. The results were in agreement with those given in standard method.

    • A study of nanostructured gold modified glassy carbon electrode for the determination of trace Cr(VI)

      Benzhi Liu Liyuan Lu Min Wang Yanqin Zi

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      A nanostructured gold modified glassy carbon electrode (Aunano/GCE) was employed for the determination of trace chromium(VI). To prepare Aunano/GCE, the GCE was immersed into KAuCl4 solution and electrodeposition was conducted at the potential of -0.4 V (vs Ag/AgCl) for 600 s. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles were deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analysed to ensure that common interference in the determination of chromium(VI) by square wave voltammetry, do not influence the electrochemical response of the latter element. The results show that this method allows for Cr(VI) determinations with a much lower detection limit (0.01 𝜇g $L^{-1}$) in the presence of excess of Cr(III) than the commonly used diethylenetriammine pentaacetic acid (DTPA) method. The method was applied to determine levels of chromium(VI) in tap water and sewage water.

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