Electroanalysis of Glutathione and Cephalexin Using the Boron- Doped Diamond Thin-Film Electrode Applied to Flow Injection Analysis

Electroanalysis of glutathione and cephalexin was studied in 0.1 M carbonate buffer pH 9.2 with boron-doped diamond thin-film electrodes by cyclic voltammetry. It was found that a well resolved and irreversible oxidation voltamogram was obtained for glutathione and cephalexin showed a discernible response. The linear dynamic range for glutathione was 0.1-5.0 mM with a detection limit of 10 μM (S/B = 3). For cephalexin, the detection limit was 5.0 mM. In addition, glutathione was studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection. The Hydrodynamic voltammogram exhibited the maximum signal-to-background ratio (S/B) at 0.75 V. The amperometric results for glutathione provided a linear dynamic range of 0.5-100 μM with a detection limit of 0.5 μM.