Simultaneous analysis of dopamine and 5-hydroxyindoleacetic acid at nanogold modified screen printed carbon electrodes

Abstract

A convenient, low cost, and sensitive electrochemical method, based on a disposable gold nanoparticles modified screen printed carbon sensor (AuNPs/SPCs), is described for the simultaneous determination of dopamine (DA) and 5-hydroxyindole acetic acid (5-HIAA). The presence of the excess of ascorbic acid and uric acid did not interfere in the determination. Field emission scanning electron microscopy (FE-SEM) and electrochemical impedance spectroscopy (EIS) were used to characterize the surface morphology of the AuNPs modified SPCs. The modified electrode exhibited good electrocatalytic properties toward the oxidation of DA and 5-HIAA. A peak potential difference of 230mV between DA and HIAA was large enough to determine DA and 5-HIAA individually and simultaneously. The anodic peak currents of DA and 5-HIAA were found to be linear in the concentration range of 0.2–100μM and 0.5–200μM with the detection limit of 8nM and 22nM, respectively. The analytical utility of method was checked by determining the DA in various pharmacological dosage forms. The utility of AuNPs/SPCs was also demonstrated successfully for the simultaneous determination of DA and 5-HIAA in human plasma and urine samples.