Facile synthesis of Bi₂O₃/BiOX mixed-phase for electrochemical detection of paracetamol

In recent times, paracetamol (N-acetyl-p-aminophenol) detection has become crucial due to its widespread clinical use combined with the public health issue of hepatotoxicity from overdose. In this research, mixed-phase Bi₂O₃/BiOX (X = Cl, Br and I) was synthesized at room temperature in a single-step solid-state reaction and for the first time used in paracetamol detection. Field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), Fourier transformed infra-red (FTIR), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC) and UV-visible Spectrophotometry were performed to determine the existence of a double phase in the compounds and to specify the characteristics. Different electrochemical methods were performed using a glassy carbon electrode modified with Bi₂O₃/BiOX to sense paracetamol. The highest surface area of 3.496 cm² was found for the Bi₂O₃/BiOCl electrode which showed an electron transfer coefficient (α) of 0.4 and electron transfer rate constant of 0.12 cm s^-1 for the process. As Bi₂O₃/BiOCl showed a superior response to the other samples, the limit of detection (LOD) = 2.24 ppm, as well as the limit of quantification (LOQ) = 7.47 ppm was determined in a linear concentration range of 1-50 ppm by cyclic voltammetry (CV). Paracetamol detection was also inspected by pulse voltammetry at a linear concentration range of 0.5-5 ppm. The sensitivity of the electrode was found to be 0.9776 µA ppm^-1, coupled with excellent reproducibility.