Role of electron transfer between bare electrode and benzoguanamine to fabricate an electrochemical sensor for drugs: Theoretical and electrochemical approach

Herein, a poly(benzoguanamine) (BNZ) modified carbon paste electrode (CPE) was applied for the electroanalysis of paracetamol (PA) in PA tablet and human urine. Theoretical evaluation of the quantum chemical parameters of benzoguanamine (BZ) via density functional theory (DFT) calculations show that it is a reactive monomer with a tendency for back bond formation with the bare carbon paste electrode (BCPE). Scanning electron microscopy (SEM) images of BCPE and BNZ modified CPE (BNZ/CPE) show that the BNZ films were deposited on the bare electrode in layers. Results of the electrochemical characterization of these electrodes in 1 mM K4[Fe(CN)6] revealed that the BNZ/CPE has a higher electrocatalytic activity towards K4[Fe(CN)6] oxidation than BCPE. The limit of detection (LOD) of PA at the BNZ/CPE was estimated as 13.2 nM over a linear dynamic range (LDR) of 0.05–0.45 μM. Also, the proposed sensor offered PA recoveries of 99.2–100.4 % and 98.4–100.8 % in PA tablet solution and human urine sample, respectively. The BNZ/CPE showed remarkable shelf-life by retaining 97.4 % of its initial current response after 21 days of application for PA electroanalysis at 7 days interval. Notably, this study is the first attempt at the application of the BNZ/CPE for PA electroanalysis.