Simultaneous determination of paracetamol and neurotransmitters in biological fluids using a carbon paste sensor modified with gold nanoparticles

Abstract

A promising electrochemical sensor was developed by electrodeposition of gold nanoparticles on a carbon paste (CP) electrode. This sensor electrode (CPE–Au_nano) was used to determine paracetamol (ACOP) and some neurotransmitters, such as dopamine (DA), epinephrine (EP), norepinephrine (NP), levodopa (L-DOPA) and serotonin (5-HT). Cyclic and differential pulse voltammetry studies indicated that the oxidation of paracetamol at the electrode surface proceeded through a two electron reversible step and was fundamentally controlled by adsorption. Further modification of the sensor by mixing the CPE–Au_nano with Nafion^® showed good sensitivity and effectively resolved the overlapping anodic peaks of these neurotransmitters (NTs) with ACOP. Also, the interfering effect of physiologically common interferences, namely ascorbic acid (AA) and uric acid (UA), on the current response of paracetamol has been studied. Nafion^® proved to increase the sensitivity of the current signal of the sensor for the oxidation of the compounds studied. Paracetamol gave a well defined oxidation peak at 430 mV in pH 7.4, which was used to quantitate the drug in the two ranges of 50 nM–50 μM and 90–270 μM with a detection limit of 7.7 nM and 28 nM, respectively. The procedure was successfully validated for the assay of paracetamol in pharmaceutical formulations. The applicability of the developed method to determine the drug in human urine samples is also illustrated.