The electrochemical oxidation of l-dopa (LD) and paracetamol (PAR) has been investigated by application of nickel hydroxide nanoparticles/multi-walled carbon nanotubes composite electrode (MWCNTs-NHNPs/GCE) using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA) methods. The modified electrode showed electrochemical responses with high sensitivity for LD and PAR determination, which makes it a suitable sensor for simultaneous sub-μmol L−1 detection of LD and PAR in aqueous solutions. Under the optimum conditions the electrode provides a linear response versus LD and PAR concentrations in the range of 0.1–100 μM and 0.06–26 μM, respectively using the DPV method. Linear responses versus LD and PAR concentrations in the range of 1–672 μM and 1–960 μM, respectively, were obtained using the CA method. The modified electrode was used for determination of LD and PAR in human urine with satisfactory results.
