Voltametric Sensor for Determination of Caffeine Using Nanohole Modified Glassy Carbon Electrode

Abstract

In this work, nanohole modified glassy carbon electrode was electrochemically fabricated and used for determination of caffeine in coffee. The surface modification procedure involved electrochemical nucleation gold nanoparticles on a glassy carbon electrode that served as a template for the nanoholes fabrication. After the electronucleation step, the electrode surface was passivated with P-notroanaline to produce molecular insulation to the electrode. The nanohole modifeied electrode was produced when the nucleated gold nanoparticle were electrochemically stripped off from the electrode surface. The developed electrode helps to minimize oxidation potential of caffeine and also to increases mass transport of caffeine to electrode surface thereby increasing sensitivity and selectivity of the modified electrode for determination of caffeine. The method enables determination of caffeine in the range from 1.0×10 −7 to 1.0×10 −3 mol L −1 ,with limit of detection of 7.28 × 10 –8 mol L -1 . The effect of theophylline and theobromine on thedetermination of caffeine was studied and found to be minimal. Besides, the sensor displayed good stability and reproducibility.