Electrochemical Determination of Caffeine in Oolong Tea Based on Polyelectrolyte Functionalized Multi-Walled Carbon Nanotube

In the present work, a voltammetric sensor for detection of caffeine was prepared by modifying a glassy carbon electrode with Nafion and PDDA-MWCNT. This sensor shows high sensitivity for caffeine determination in the range from 0.3 to 80 μM, and the detection limit is 0.05 μM. Moreover, the sensor exhibits good stability, reproducibility and high activity for electrochemical oxidation of caffeine. Thus, it is available for the quantitative analysis of caffeine in Oolong tea.