The preparation and electrochemical behavior of a carbon-paste electrode modified with an oxovanadium (IV) Schiff-base complex was studied. The modified electrode showed efficient catalysis in the electrochemical oxidation of methimazole (MMZ), an anti-hyperthyroid drug. The catalytic effect was observed for VIII oxidation peak which was produced via disproportionation of VIV in acidic solution. The diffusion coefficient (D) of MMZ and the rate constant of catalytic reaction (k) were estimated by chronoamperometry. Determination of MMZ was carried out using differential pulse voltametry. A linear dynamic range of 9 × 10–7 to 1 × 10-4 M with a detection limit of 8 × 10-7 M and a limit of quantitation of 2.6 × 10–6 M was resulted for the drug. The relative standard deviation for determination of 20 μM of the drug was found to be 1.7%. The method was used for the quantitation of MMZ in pharmaceutical formulations successfully.
Key words: Methimazole, determination, tablets, modified-carbon paste electrode.
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