Amperometric determination of paracetomol by a surface modified cobalt hexacyanoferrate graphite wax composite electrode

A stable electro active thin film of cobalt hexacyanoferrate (CoHCF) was deposited on the surface of an amine adsorbed graphite wax composite electrode using a simple method. Cyclic voltammetric experiments showed two pairs of well defined peaks for this CoHCF modified electrode which exhibited excellent electrocatalytic property for the oxidation of paracetomol at a reduced overpotential of 100 mV and over a concentration range of 3.33 × 10⁻⁶ to 1.0 × 10⁻³ M with a slope of 0.208 μA/μM with good sensitivity. The influence of the supporting electrolyte on peak current and peak potential were also obtained in addition with effects of common interference (e.g., ascorbic acid) on the response of the modified electrode. Various parameters that influence the electrochemical behavior of the modified electrode were optimized by varying scan rates and pH. Electrochemical impedance spectroscopy studies suggested that the electrode reaction of the CoHCF film is mainly controlled by transport of counter ion. The immobilized CoHCF maintained its redox activity showing a surface controlled electrode reaction with the electron transfer rate constant (K_s) of 0.94 s⁻¹ and charge transfer coefficient of 0.42. Hydrodynamic and chronoamperometric studies were done to explore the utility of the modified electrode in dynamic systems. The results of the differential pulse voltammetry (DPV) using the modified electrode was applied for the determination of paracetomol in commercially available tablets. The results obtained reveal that the electrode under study could be used as an effective sensor for online monitoring of paracetomol.