Surface Modification of Carbon Paste Electrode with Nano-Structured Modifiers: Application for Sub-Nano-Sensing of Paracetamol

A new composite for electrochemical sensing of a pain reliever drug, paracetamol (APAP), has been fabricated based on gold nanoparticles/carbon nanotubes/ionic liquid crystal modified carbon paste electrode (AuCNTILCCP). This modification improved the sensor characteristics in terms of fast electron transfer rate, high sensitivity, good selectivity and noticeably low detection limit. Inclusion of different ionic liquids proved less effective toward the electrochemical oxidation of APAP compared to ionic liquid crystal used in this study. The composite electrode (AuCNTILCCP) was successfully used for the determination of APAP in presence of common interfering compounds such as ascorbic acid, dopamine, tryptophan and terazosin. The composite electrode was directly used for direct determination of APAP in urine and drug formulation samples. Linear dynamic range was obtained for the calibration curve in urine from 4 nmol L −1 to 0.09 μmol L −1 ; detection limit: 0.051 nmol L −1 ; quantification limit: 0.17 nmol L −1 ; R 2 : 0.996 and sensitivity: 413 μA/ μmol L −1 . Figures of merits for the sensor performance including: stability, reproducibility, repeatability, robustness, and precision are reported.