Voltammetric determination of paracetamol in pharmaceutical tablet samples using anthraquinone modified carbon paste electrode

Abstract After cyclic voltammetric investigation of the electrochemical behavior of paracetamol and dependence of peak current on scan rate and pH; square wave voltammetric method based on anthraquinone modified carbon paste electrode was developed for direct determination of paracetamol in pharmaceutical tablet samples. In contrast to the peak potential at the unmodified electrode, appearance of the oxidative peak at a lower potential at the modified electrode indicated a catalytic property of the modifier towards paracetamol oxidation. While the observed peak potential shift with scan rate confirmed the irreversibility of the reaction, comparable correlation coefficients for the dependence of peak current of scan rate and square root of scan rate indicated that the irreversible oxidation reaction was controlled by both diffusion and adsorption. The peak current response of the developed method showed a linear dependence on the paracetamol concentration in the range 5 to 150 ppm. Excellent recoveries (93.5%), wide dynamic range, low limit of detection (0.13 µM), and limit of quantification (0.43 µM) validated the method for determination of paracetamol in real samples. The proposed method was applied for paracetamol determination in four brands of tablet samples (Julphare Aldol, Panadol Adva, Kelvin, and Para Denk) all of which labeled 500 mg/tablet. The paracetamol content of the analyzed four brands of tablet samples using the reported method was ranged between 83.04% (Panadol Adva, Kenya) and 95.08% (Para Denk, Germany) of the labeled amount. The discrepancy might be ascribed to the possible matrix difference among the companies and/or failure of the companies to comply the standard.