Simultaneous detection of dopamine, uric acid, and ascorbic acid using SnO2 nanoparticles/multi-walled carbon nanotubes/carbon paste electrode

A novel SnO2 nanoparticles/multi-walled carbon nanotubes/carbon paste electrode (nanoSnO(2)/MWCNTs/CPE) was prepared for simultaneous detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA) via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The novel nanoSnO(2)/MWCNTs/CPE electrode showed high electrochemical catalytic behavior for DA, UA, and AA. The three compounds could be completely separated on the electrode in CV and DPV at optimal conditions. DPV provided larger peak potential separations and higher response sensitivities of DA, UA, and AA compared to CV. In DPV, there are linear relationships between the peak currents and the concentrations in the ranges of 0.3-50 mu M for DA, 3-200 mu M for UA, and 0.1-5 mM for AA, with the detection limits (S/N = 3) of 0.03, 1, and 50 mu M for DA, UA, and AA, respectively. The proposed method was applied for the simultaneous detection of DA, UA, and AA in human urine samples, with recoveries of 91.0%, 97.4%, and 103.0% for DA, UA, and AA, respectively. The relative standard derivations (RSDs, n = 5) were 2.8-4.4%.