Simultaneous electrochemical determination of dopamine, ascorbic acid and uric acid in the presence of sodium dodecyl sulphate using a multi-walled carbon nanotube modified carbon paste electrode

A carbon paste electrode modified with multi-walled carbon nanotubes (CPE/MWCNT) was prepared as a biosensor for the simultaneous determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA) in the presence of sodium dodecyl sulphate (SDS). The nature and surface morphology of the bare CPE and fabricated MWCNTs were characterized by scanning electron microscopy (SEM). The CPE/MWCNT exhibited excellent electrocatalytic activity towards the oxidation of DA, AA and UA in the presence of SDS in 0.2 M phosphate buffer (PB) solution (pH 3.0). The separations of the anodic peak potentials of AA/DA, DA/UA and AA/UA at the surface of the modified electrode using differential pulse voltammetry (DPV) were obtained as 108.0, 150.0 and 260.0 mV, respectively. The proposed method was successfully applied for the determination of DA, AA and UA in real samples with satisfactory results.