| The fabrication of chemistry sensor is one of the most interesting fields of analytical chemistry. Especially, the application of the magnetohydrodynamics (MHD) in electrochemistry is distinguished. On the other hand, bismuth film electrodes are currently attracting more and more attentions. In this thesis, MHD was used for the stripping voltammetric determination of heavy metal ions in the complex samples. Green bismuth film electrode was successfully used for determination of zinc in milkvetch. The combination of MHD and bismuth film electrode not only provided an environmental friendly method for the heavy metal ions, but also improved the sensitivity and reproducibility for the determination. The creative works of this thesis are summarized as follows:1. A novel method for the ultratrace determination of Cd2+ and Pb2+ based on magneto-voltammetry was developed. In the presence of a low strength magnetic field of 0.6 T, square wave stripping voltammetry (SWSV) of Cd2+ and Pb2+ was performed in this determination. A high concentration of redox species Fe3+ was added to the analytes to generate a large cathodic current during the preconcentration step. A large Lorentz force arising from the flux of net current through the magnetic field resulted in convective solution flow due to magnetohydrodynamics. Then more metal ions at a faster rate deposited on the electrode surface and an enhancement as large as 160% for the stripping peak current was observed. Under the optimal conditions, this method exhibits high sensitivities of 5.67μA·μM-1 for Cd2+ and 6.98μA·μM-1 for Pb2+, over the 1×10-8-1×10-6 M range. Detection limits as low as 9.0×10-10 and 8.6×10-10 M for Cd2+ and Pb2+ were obtained with a 2-min preconcentration time, respectively. The method was successfully applied to detect Cd2+ and Pb2+ in real water samples and the results were in agreement with atomic absorption spectrometry.2. Bismuth film electrode (BiFE) was shown to be an attractive alternative to common mercury film electrode (MFE) for anodic stripping voltammetric measurements. In this study, bismuth film, that was in situ deposited onto glassy carbon electrode, was used to detect zinc content of milkvetch, used in traditional Chinese medicine. The Zn2+ was reduction at -1.4 V on the glasscarbon substrate. Then, the preconcentrated metals were oxidized by scanning the potential of the electrode from -1.4 V to -0.6 V using a square-wave waveform. Variables affecting the response have been evaluated and optimized. Experimental results showed a high response, with a good linearity (between 5×10?8 M and 1×10?6 M),a good precision (R.S.D.=3.8%) and a low detection limit (9.6×10?9 mol L?1 with a 120 s anodic). The anodic stripping performance makes the bismuth film electrode very desirable for measurements of trace nutritive element zinc in milkvetch and should impart possible restrictions on the use of mercury electrode.3. A novel method for the determination of Pb2+ with bismuth film electrodes (BFEs) based on magneto-voltammetry was investigated. In the presence of a 0.6 T external magnetic field, square wave voltammetry of Pb2+ was performed with BFEs. A high concentration of Fe3+ was added to the analytes to generate a large cathodic current during the preconcentration step. A Lorentz force from the flux of net current through the magnetic field resulted in convection. Then more Pb2+ deposited onto the electrode and larger stripping peak currents were observed. BFEs that were prepared by simultaneously depositing the bismuth and Pb2+ on an electrode offered a mercury-free environment for this determination. This method exhibits high sensitivity of 4.61μA·μM-1 for Pb2+ over the 1×10-8-1×10-6 M range. Detection limit as low as 8.5×10-10 M was obtained with only 1-min preconcentration. The method was successfully applied to determine Pb2+ in real water samples.
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