Researchers have developed a modified carbon paste electrode combining reduced graphene oxide and poly(L-tryptophan) to achieve electrocatalytic oxidation and differential-pulse voltammetric determination of paracetamol.

To fabricate the working interface, graphene oxide was chemically reduced using L-ascorbic acid and subsequently deposited onto the surface of a carbon paste electrode. The resulting modified base was then coated through two-cycle electropolymerization of L-tryptophan.

Electrochemical evaluations revealed that the composite material substantially boosted analytical signal strength compared with an unmodified electrode. Specifically, the modified electrode increased the paracetamol anodic current by 42.9-fold relative to the bare carbon paste electrode. In addition to the enhanced current response, the composite architecture lowered the required oxidation potential for paracetamol by 76.5 millivolts.

The apparent electroactive surface area expanded from 0.0169 square centimeters on the untreated substrate to 0.0317 square centimeters on the composite electrode. Furthermore, an investigation of scan-rate dynamics indicated that the electrocatalytic reaction operates under a mixed diffusion and adsorption control mechanism.

Measurements tracking peak potential across different pH values revealed a shift of -56.33 millivolts per pH unit. This specific slope supported a reaction mechanism involving approximately equal numbers of participating protons and electrons during the electrochemical transformation.

Using differential-pulse voltammetry, the sensor exhibited a linear quantitative response across a paracetamol concentration range from 40 to 240 micromolar, yielding a correlation coefficient R-squared value of 0.9954. The analytical calibration established a sensitivity of 0.04925 microamperes per micromolar, alongside a limit of detection of 20.96 micromolar and a limit of quantification of 69.88 micromolar.

The practical analytical performance of the modified system was tested through recovery trials in commercial pharmaceutical tablets. Within the quantitative linear interval, the composite electrode delivered paracetamol tablet recovery rates ranging between 98.79 percent and 104.84 percent. The experimental findings illustrate the cooperative electrocatalytic behavior between reduced graphene oxide and poly(L-tryptophan) in an accessible analytical platform.

The authors highlight that the resulting composite interface offers an accessible, low-cost platform specifically targeted for routine pharmaceutical paracetamol analysis.

Subject of Research: Electrochemical determination of paracetamol using modified carbon paste electrodes

Article Title: Electrocatalytic Oxidation and Differential-Pulse Voltammetric Determination of Paracetamol Using a Reduced Graphene Oxide/Poly(L-tryptophan)-Modified Carbon Paste Electrode

Article References: Sajjan, A. S., Das, S. N., Chadchan, K. S., & Malladi, R. S. (2026). Electrocatalytic Oxidation and Differential-Pulse Voltammetric Determination of Paracetamol Using a Reduced Graphene Oxide/Poly(L-tryptophan)-Modified Carbon Paste Electrode. Catalysis Letters, 156(12), Article 320. https://doi.org/10.1007/s10562-026-05562-7

Image Credits: AI Generated

DOI: 10.1007/s10562-026-05562-7

Keywords: paracetamol, reduced graphene oxide, poly(L-tryptophan), carbon paste electrode, electrocatalytic oxidation, differential-pulse voltammetry, electropolymerization, L-ascorbic acid, sensor, electrochemistry, limit of detection, limit of quantification, pharmaceutical analysis, voltammetric determination, tablets, diffusion control, adsorption control