In situ Electrochemical Synthesis of a Composite Film Containing Nickel Hexacyanoferrate and Bentonite Clay for the Sensitive Determination of Acetaminophen and Dopamine

A composite film of nickel hexacyanoferrate (NiHCF) and bentonite (Bt) clay (abbreviated as NiHCF-Bt) is synthesized by an in situ electrochemical method. For this synthesis, nickel ions are immobilized on Bt clay by an ion-exchange process, equilibrating Bt clay with nickel nitrate. On a glassy carbon electrode (GCE), the nickel ion-exchanged Bt clay (Ni2+-Bt) is coated to get the modified electrode which is represented as GCE/Ni2+-Bt. The NiHCF-Bt composite film is prepared on the GCE surface using the GCE/Ni2+-Bt and scanning the electrode potentials between -0.10 to 1.00 V continuously in an aqueous solution containing potassium hexacyanoferrate and potassium chloride. This NiHCF-Bt modified GCE (GCE/NiHCF-Bt) exhibits redox peaks due to the oxidation and reduction of the central metal ion, Fe2+. The electro-generated Fe3+ present in the GCE/NiHCF-Bt, electrocatalytically oxidizes a range of drugs like acetaminophen (AC), dopamine (DA), and tyrosine (TY) at decreased overpotentials with high current. This property is advantageously used for the precise quantification of AC, DA, and TY. Sensitivity, limit of detection, and linear calibration range for the determination of AC are found to be 0.20 mu A mu M-1 cm(-2), 1.5 mu M, and 25.0-1000.0 mu M, respectively. Further, the amount of AC present in pharmaceutical products is satisfactorily quantified which demonstrated the use of the NiHCF-Bt composite film in electroanalysis.