Carbon Nanotubes‐Ionic Liquid Composite for Electrooxidation of Trimethoprim

This study presents a new, simple, fast, and cost‐effectivemethod for the identification and quantification of Trimethoprim in pharmaceutical tablets. It employs an electrochemical sensor based on a glassy carbon electrode modified with 4hr functionalized multiwalled carbon nanotubes, 1‐butyl‐3‐methylimidazolium hexafluorophosphate, and Nafion. Physical characterization revealed good dispersion of modifiers across the electrode surface and a high dielectric constant. Electrochemical testing of the developedsensor was performed using the ferro/ferricyanide system, and data showed improved electron transfer, confirming its suitability as a voltammetric sensor. Experimental and voltammetric optimizations for Trimethoprim analysis revealed that the Britton–Robinson buffer at pH 5.0 was the optimal supporting electrolyte, with an accumulation potential of −0.5 V for 120 s, a potential pulse frequency of 30 s −1 , a pulse amplitude of 25 mV, and a pulse potential increment of 2 mV. Analytical curves were prepared in triplicate using the standard addition method, yielding a linear range from 0.49 to 2.49 μmol L −1 , a calculated limit of detection of 0.0970 μmol L −1 , and a limit of quantification of 0.293 μmol L −1 , which is lower than similar data obtained by traditional chromatographic procedures. The precision of the proposed procedure was evaluated using repeatability and intermediate precision, yielding a relative standard deviation of less than 2.0%, indicating a satisfactory outcome. Accuracy in pharmaceutical samples, evaluated by recovery experiments, yielded values of around 103.0%, highlighting the suitability of the developed sensor for Trimethoprim analysis.