Sensitive Determination of Acetaminophen in the Presence of Dopamine and Pyridoxine Facilitated by their Extent of Interaction with Single‐walled Carbon Nanotubes

Abstract

AbstractSingle‐walled carbon nanotubes (SWCNTs) were immobilized on glassy carbon (GC) electrode by drop casting The resulting modified electrode (represented as GC/SWCNTs) efficiently oxidizes acetaminophen (AC), dopamine (DA) and pyridoxine (PY) by decreasing the respective oxidation potentials and increasing peak currents in comparison to bare GC electrode. The extent of lowering of overpotentials is in the order of AC>PY>DA, in agreement with the order of decrease in the HOMO‐LUMO energy gap (ΔE) of these analytes, as determined from Density Functional Theory (DFT) calculations. DFT calculations further reveal that due to the interaction of the analytes on the SWCNT(10,10) there is a negative charge density transfer (higher probability of electron transfer, lower ΔE value) to the frontier molecular orbitals of the analytes, which eases their oxidation. Since AC, DA and PY oxidize distinctly at distinct potential values, the present SWCNTs modified electrodes could be used to simultaneously determine them. Cyclic voltammetry, differential pulse voltammetry and amperometry techniques are utilized to understand the electrochemical characteristics of the analytes (AC, DA and PY) and subsequent sensing of them at the GC/SWCNTs electrode. The electrode is then applied to the determination of AC as a case study. Sensitivity, detection limit and linear calibration range for the AC are found to be 7.9 μA μM−1 cm−2, 1.1 μM and 2.0–100.0 μM, respectively. The increased electroactive surface area of the GC/SWCNTs increases the oxidation peak currents and hence increases the sensitivity of the determination.