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.

Keywords:

• anthraquinone modified carbon paste electrode
• cyclic voltammetry
• paracetamol
• tablet formation samples
• square wave voltammetry

PUBLIC INTEREST STATEMENT

There are a lot of well established conventional reported methods for determination of paracetamol. Whereas most of these methods are so expensive and use organic solvents which are not environmentally friendly, Voltammetric methods use relatively cheaper instruments and usually aqueous medium. The active ingredient in “paracetamol tablet” used as a pain killer is an electroactive that can be detected using voltammetric techniques. Developing a voltammetric method for the determination of such electroactive species helps researchers interested in the field to monitor their levels before they cause health problems specifically on the users and the environment in general. Carbon paste is the simplest and hence the cheapest form of the carbon- based electrodes used in voltammetry. Modification of an electrode including carbon paste usually improves its response for the analyte may be due to increased surface area, adsorption, or electron exchange. The developed method using anthraquinone modified carbon paste electrode was used for determination of paracetamol in four brands of paracetamol tablets with an excellent accuracy.

Competing Interests

The authors declare no competing interests.

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

Meareg Amare

Dr Meareg Amare, who has MSc in analytical chemistry and PhD in physical chemistry is now an Associate Professor at the Department of Chemistry, Bahir Dar University, Ethiopia. He has over 20 articles published in reputable journals most of which are on electrochemical method development for determination of electroactive pharmaceutical ingredients. He is also working on method development for assessment of the level of selected pollutants in industrial effluents including tanneries.