Determination of Caffeine at a Nafion-Covered Glassy Carbon Electrode

A simple differential pulse voltammetric method based on a Nafion-covered glassy carbon electrode was developed for the quantitative determination of caffeine in cola beverages. The modified electrode exhibits a clear improvement of the current response compared to that observed at a bare glassy carbon electrode. The method allows quantifying the analyte in the 9.95×10-7-1.06×10-5 M range, with a detection limit of 7.98×10-7 M in 0.1 M sulfuric acid solutions. The developed procedure was tested by recovery studies. The results are described and discussed in the light of the existing literature.