A Carbon Nanotube Modified Electrode for Determination of Caffeine by Differential Pulse Voltammetry

A simple and sensitive electrochemical detection of caffeine (CAF) using a single-walled carbon nanotubes on carbon-ceramic electrode (SWCNT/CCE) is reported. CAF was oxidized at the surface of the modified electrode to produce an anodic peak at 1.38 V versus the saturated calomel electrode in 0.01 mol/L, pH 1.7 H2SO4 solution in cyclic voltammetry. The experimental parameters, namely, type of electrolyte, pH value, and amount of SWCNTs casted, were optimized. Using the optimum conditions, the anodic peak current in differential pulse voltammetry was linear with CAF concentration in the range of 2.5 x 10(-7)-1.0 x 10(-4) mol/L. The detection limit was 1.2 x 10(-7) mol/L (S/N = 3). The modified electrode exhibited good stability and can be easily regenerated. The relative standard deviation of the peak current obtained for a 5.0 x 10(-5) mol/L CAF solution was 3.0%. The influence of some important biological compounds, namely, ascorbic acid, dopamine, and uric acid and addictive compounds like codeine, morphine, and acetaminophen on the CM; anodic peak current was examined. The method was successfully applied for the determination of CAF in some practical samples.