Enhancing dopamine detection using a glassy carbon electrode modified with MWCNTs, quercetin, and Nafion

Glassy carbon (GC) electrode was modified using multi-wall carbon nanotubes (MWCNTs), quercetin (Q) and Nafion in this sequence. The thus modified electrode was used for the detection of dopamine (DA) in the presence of equimolar ascorbic acid (AA). It is demonstrated in this study that MWCNTs can increase the current response of DA by five-fold and Q can reduce the oxidation overpotential of DA by about 60 mV, compared to these parameters obtained with a bare GC electrode. It is also shown that a layer of Nafion can virtually eliminate the interference of AA for the detection of DA. The GC/MWCNTs/Q/Nafion electrode (hereafter also called composite electrode) shows a current density of about 900 microA cm(-2) for DA, compared to the value of 80 microA cm(-2) of the GC electrode and to the value of 390 microA cm(-2) of the GC/MWCNTs electrode. The 11-fold enhancement in the sensitivity of the GC electrode for DA determination is attributed to the composite modification of the electrode, and is substantiated through various cyclic voltammetric experiments. Cyclic voltammetry (CV) and linear sweep voltammetry were used to characterize the electrodes. Calibration curves of batch and flow systems were obtained by amperometry for the detection of DA. Additionally, the composite modified electrode was tested with a human serum sample for the determination of DA and was found to be promising at our preliminary experiments.