Thionine supported on multi-walled carbon nanotubes for modification of carbon paste electrode; application to simultaneous voltammetric determination of ascorbic acid and acetaminophen in the presence of isoniazid

A carbon paste electrode (CPE) modified with thionine supported on multi-walled carbon nanotubes (MWCNTs), was successfully used to simultaneously determine ascorbic acid (AA) and acetaminophen (AC) in the presence of isoniazid (INZ).The electrochemical response characteristics of the modified electrode toward AA, AC and INZ were investigated by cyclic and differential pulse voltammetry (CV & DPV). The results show an efficient catalytic role for the electro-oxidation of AA and AC, leading to a remarkable peak potential separation (~303mV) for two compounds. On the other hand, the presence of isoniazid, which is considered as important drug interference for AC, does not affect the voltammetric responses of the mixture solution. The mechanism of the modified electrode was analyzed by monitoring the CVs at various potential sweep rates and pHs of the buffer solutions. Under the optimum conditions, the calibration curves for AA, AC and INZ were obtained in the range of 1×10-6-1×10-4 M, 1×10-7-1×10-4 M and 1×10-6-1×10-4M, respectively. The prepared modified electrode shows several advantages such as simple preparation method, high sensitivity, long-term stability, ease of preparation and regeneration of the electrode surface by simple polishing and excellent reproducibility. The proposed method was applied to detect AA, AC and INZ in commercial drugs and in plasma samples and the obtained results were satisfactory.

کلیدواژه ها:

Carbon nanotube ، Thionine ، Ascorbic acid ، Acetaminophen ، Isoniazid