Electropolymerisation of l-arginine at carbon paste electrode and its application to the detection of dopamine, ascorbic and uric acid

Cyclic voltammograms of simultaneous detection of AA, DA and UA of the different concentration in 0.1 M ABS of pH 5.6 at a BCPE overlapped (solid curve). While three distinct anodic peaks were obtained at the (dotted curve). The observation clearly indicates that the poly( l-arginine)/CPE has separated each voltammetric signals of AA, DA and UA. [Display omitted] ► Biopolymer on the bare carbon paste is fabricated by electropolymersation under the controlled potential application by cyclic voltammetric method. ► Dopamine is one of the excitory neurotransmitters that play an important role in physiological events. ► Simultaneous determination of DA, AA and UA is very important in analytical and clinical chemistry by using the modified electrodes that are able to resolve the voltammetric responses. l-arginine was electropolymerised on a carbon paste electrode (CPE) to form the biopolymer by free radical formation in the electro oxidation process of the amino and carboxylic group containing compound by cyclic voltammetric technique. The modified electrode shows an excellent electrocatalytic activity towards the oxidation of both dopamine (DA) and ascorbic acid (AA). It was demonstrated that the deposited biopolymer has positive charges over the bare carbon electrode surface, which leads to the formation of electrical double layer made the fast electron transfer process could leads to the diffusion of dopamine, ascorbic acid and uric acid on their charge gradient by cyclic voltammetric technique. The response of the sensor was tested towards the different dopamine concentration. The catalytic peak current obtained was linearly related to DA concentrations in the ranges of 5 × 10 −5 to 1 × 10 −4 M L −1 with correlation co-efficient of 0.9924 which reveals the adsorption controlled process. The detection limit for dopamine was 5 × 10 −7 M L −1. The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid (AA) and response is fast stable, reliable, resistant to biofouling and can be applied for the real sample analysis in medical, pharmaceutical and biotechnological sectors. The adsorption-controlled process and kinetic parameters of the poly( l-arginine) were determined using electrochemical approaches.