Simultaneous electrochemical determination of dopamine, uric acid and ascorbic acid using silver nanoparticles deposited on polypyrrole nanofibers

Silver nanoparticles modified polypyrrole (PPy) nanofibers were fabricated and used for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) with good selectivity and high sensitivity. Polypyrrole nanofibers were prepared through electrodeposition, while silver nanoparticles were deposited on PPy nanofiber by electrodeposition and electrochemical oxidation in situ. The morphology and structure of silver nanoparticles/polypyrrole nanocomposite (Ag/PPy) were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR). Compared with the bare glassy carbon electrode (GCE) and PPy/GCE, Ag/PPy modified GCE (AgPPy/GCE) exhibited much higher electrocatalytic activities toward oxidation of AA, DA, and UA with increasing the peak currents and decreasing the oxidation overpotentials. Cyclic voltammetry (CV) results showed that DA, AA, and UA could be detected selectively and sensitively at Ag-PPy/GCE with peak-to-peak separation of 120 mV and 170 mV for AA-DA and DA-UA, respectively. The calibration curves for AA, DA, and UA were obtained in the range of 10-580 mu M, 0.5-155 mu M and 2-100 mu M, respectively. The lowest detection limits (S/N=3) were 1.8 mu M, 0.1 mu M, and 0.5 mu M for AA, DA, and UA, respectively. With good selectivity and sensitivity, the present method was applied to determination of DA in injectable medicine and UA in urine sample.