Woltamperometric determination of copheine on electrode modified by Nafion film and mixed valent iridium oxides in energy beverages

Abstract. It was found that mixed valent iridium oxides electrodeposited on the surface of a glass-carbon electrode exhibit catalytic activity in the oxidation of caffeine. A more pronounced catalytic effect was obtained on the electrode modified with a composite based on a film of perfluorinated sulfonated polymer (Nafion) and mixed valent iridium oxides. A selective voltammetric method for the determination of caffeine was developed. A linear logarithmic dependence of current on caffeine concentration was observed in the range from 1×10–8 to 5×10–3 M. The developed method was used in the determination of caffeine in energy drinks.