Voltammetric determination of caffeine in beverages using a chemically modified electrode

Abstract

A Nafion–ruthenium oxide pyrochlore chemically modified electrode is used for the determination of caffeine in beverages by square-wave voltammetry. Compared to a bare glassy carbon electrode, the chemically modified electrode exhibits a marked enhancement of the current response. A linear calibration curve is obtained over the 5–200 µM range in 0.05 M HClO₄ solution with a detection limit (3ς) of 2 µM. The results of 15 successive repetitive measurement–regeneration cycles showed a relative standard deviation of 2.7% for 10 µM caffeine. Thus, the electrode renewal gives a good reproducible surface. Quantitative analysis was performed by the standard addition method for caffeine content in tea, coffee, decaffeinated coffee, and cola beverages.

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