Monolayer modification of glassy carbon electrode by using propionylcholine for selective detection of uric acid

A monolayer modified glassy carbon electrode by using propionylcholine (denoted as PCh/GCE) was fabricated via cyclic voltammetry. A strong electrochemical catalytic activity toward the oxidation of uric acid (UA) was observed. The peak potential separation of differential pulse voltammetry for UA and ascorbic acid (AA) was about 293 mV, allowing the determination of UA in the presence of high concentration of AA. X-ray photoelectron spectroscopy (XPS), in situ UV–visible spetroelectrochemistry (UV–vis) and electrochemical impedance spectrum techniques were used for characterization. It was demonstrated that the PCh was hydrolyzed to choline (Ch) and propionic acid as soon as the Ch covalently bounded on the carbon surface accompanying with an imbedding of the propionic acid into the Ch modified layer, forming the novel monolayer modification of choline residue and propionic acid interdigitated assembling. In optimal condition, a linear range of 0.07–70 μM, a detection limit of 0.02 μM (3σ) in the presence of 0.1 mM AA were achieved. Also, choline, acetylcholine and butylcholine modified GCEs were similarly prepared for comparison. Utility of the PCh/GCE was demonstrated by the measurement of UA in human urine without any pretreatment.