Sensitive detection of gallic acid based on polyethyleneimine-functionalized graphene modified glassy carbon electrode

A new electrochemical sensor was developed based on polyethyleneimine-functionalized graphene oxide (PEI-rGO) modified glassy carbon electrode (PEI-rGO/GCE). The synthetic positive charged PEI-rGO had good electron transfer ability, large specific surface area, prominent biocompatibility, and excellent adsorption. Its morphology and microstructure was characterized by scanning electron microscopy. The new electrode was firstly used for the detection of gallic acid, which exhibits superior performance in comparison to the bare glassy carbon electrode and graphene oxide modified glassy carbon electrode. The experimental conditions such as pH, adsorption time, and scan rate were optimized for the determination of gallic acid. Under optimum conditions, the linear regression equation of gallic acid was ip = 12.76c − 11.44 (ip: μA, c: mg/L, R = 0.9887) from 0.1 to 10 mg/L with a detection limit (S/N = 3) of 0.07 mg/L. The method has been successfully applied to the determination of gallic acid in samples of green tea and black tea.