2,2′-(1,3-Propanediylbisnitriloethylidine)bis-hydroquinone/TiO2 nanoparticles modified carbon paste electrode for selective determination of dopamine in the presence of uric acid and tryptophan

A modified carbon paste electrode with 2,2'-(1,3-propanediylbisnitriloethylidine)bis-hydroquinone (PBNBH) and TiO2 nanoparticles has been fabricated and used to study the catalytic oxidation of dopamine (DA), uric acid (UA) and tryptophan (Trp). The overpotential of DA reduced about 0.36 V. Based on its strong catalytic function toward the oxidation of DA, UA and Trp, the modified electrode resolved the overlapping voltammetric response of DA, UA and Trp into three well-defined voltammetric peaks with square wave voltammetry (SWV), which can be used for the simultaneous determination of these species in a mixture. The catalytic peak currents obtained from SWV were linearly dependent on the DA concentration in the range 2.0-10.0 mu M and 10.0-1000.0 mu M with correlation coefficients of 0.9993 and 0.9998, respectively. The detection limit (2 sigma) for DA was 0.47 mu M. The modified electrode showed good sensitivity and selectivity and has been applied to the determination of DA, UA and Trp simultaneously in real samples with satisfactory results.