A sensitive electrochemical sensor for paracetamol based on a glassy carbon electrode modified with multiwalled carbon nanotubes and dopamine nanospheres functionalized with gold nanoparticles

We describe an electrochemical sensor for paracetamol that is based on a glassy carbon electrode modified with multiwalled carbon nanotubes and dopamine nanospheres functionalized with gold nanoparticles. The functionalized nanospheres were prepared by a chemical route and characterized by scanning electron microscopy. The well-dispersed gold nanoparticles were anchored on the dopamine nanosphere via a chemical reduction of the gold precursor. The stepwise fabrication of the modified electrode and its electrochemical response to paracetamol were evaluated using electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode displayed improved electrocatalytic activity towards paracetamol, a lower oxidation potential (371 mV), and a larger peak current when compared to a bare electrode or other modified electrodes. The kinetic parameters governing the electro-oxidation of paracetamol were studied, and the analytical conditions were optimized. The peak current was linearly related to the concentration of paracetamol in 0.8-400 mu M range, and the detection limit was 50 nM (at an SNR of 3). The method was successfully applied to the determination of paracetamol in spiked human urine samples and gave recoveries between 95.3 and 105.2 %.