Studies on Novel Flow - Based Electrochemical Methods for Trace and Ultratrace Analysis of Some Harmful Substances

55 This works describes the development of novel flow-based electrochemical methods and their application to the determination of some harmful substances: antibiotics (lincomycin, chloramphenicol), antibacterial agents (sulfonamides), and heavy metals (lead, cadmium and zinc), in pharmaceuticals, foods, and drinking water. The electroanalysis of lincomycin was investigated using boron-doped diamond thin film (BDD) electrodes. First, the electrochemistry of lincomycin was studied by cyclic voltammetry as a function of pH of the solution, scan rate and the concentration of lincomycin. Comparison experiments were carried out using glassy carbon electrode. Boron-doped diamond thin film electrode provided wellresolved oxidation irreversible cyclic voltammogram. It was found that the peak position was 1.2 V (vs. Ag/AgCl reference electrode). Second, the amperometric detection with BDD electrode was coupled with the flow injection analysis for the determination of lincomycin. The linear range of 0.25 to 125 μM and the detection limit of 0.02 μM were obtained. This purposed method was also applied to a drug formulation sample. It was found that the results (293 mg mL) were comparable to those labeled (300 mg mL). The percent recovery was shown in a range of 96.32 to 103.1. Sulfonamides (SAs) were electrochemically investigated using cyclic voltammetry at a boron-doped diamond (BDD) electrode. Comparison experiments were carried out using a glassy carbon electrode. The BDD electrode provided well-resolved oxidation, irreversible cyclic voltammograms and higher current signals when compared to the glassy carbon electrode. Results obtained by using the BDD electrode in a flow injection system coupled with amperometric detection were illustrated. The optimum potential from a hydrodynamic voltammogram was found to be 1,100 mV vs. Ag/AgCl, which was chosen for the HPLC-amperometric system. Excellent results of linear range and detection limit were obtained. This method was also used for determination of sulfonamides in egg samples. The standard solutions of 5, 10, and 15 ppm were spiked in a real sample, and recoveries were found to be between 90.0 and 107.7%. The electrochemical properties of chloramphenicol at a boron-doped Studies on Novel Flow-Based Electrochemical Methods for Trace and Ultratrace Analysis of Some Harmful Substances