Electrochemical response of dopamine at a penicillamine self-assembled gold electrode

The penicillamine (Pen) self-assembled monolayer (SAM) modified gold electrode (Pen/Au) is demonstrated to catalyze the electrochemical response of dopamine (DA) by cyclic voltammetry. A pair of well-defined redox waves was obtained and the calculated standard rate constant (ks) is 3.88×10−3 cm/s at the self-assembled electrode. The electrode reaction is a quasi-reversible process. The oxidation peak of DA can be used to determine the concentration of DA. The peak current and the concentration of DA are a linear relationship in the range of 2.0×10−5 M to 8.0×10−4 M. The detection limit is 4.0×10−6 M. By ac impedance spectroscopy the apparent electron transfer rate constant (kapp) of Fe(CN)3−/Fe(CN)4− at the Pen/Au electrode was obtained as 2.08×10−5 cm/s. The Pen SAM was characterized with X-ray photoelectron spectroscopy (XPS), grazing angle FT-IR spectroscopy and contact angle goniometer.