Electrochemical synthesis of polyaniline in surface-attached poly(acrylic acid) network, and its application to the electrocatalytic oxidation of ascorbic acid.

Acrylic acid was first electropolymerized on the surface of a gold electrode. Then, polyaniline (PANI) was electrodeposited on the poly(acrylic acid) (PAA) network to give a PANI–PAA composite film. Scanning electron microscopy and electrochemical studies confirmed the formation of PANI–PAA composite which exhibited excellent electroactivity over a wide pH range. The electro-oxidation of ascorbic acid (AA) was studied in detail. The modified electrode exhibits significantly reduced oxidation overpotential. The response towards AA is linear in the range 1.0 μM to 9.3 mM ( R = 0.9997, n = 33) at a potential of 0.1 V (vs. SCE). The sensitivity is 207 μA mM^-1 cm^-2, and the detection limit is 1.0 μM (S/N = 3). Interferences by uric acid and dopamine are negligible. The electrode thus enables sensitive and selective determination of AA, with a performance superior to many other PANI–based ascorbate sensors. [ABSTRACT FROM AUTHOR]