Development of an HPLC/ELCD Analytical Method for the Determination of Caffeine, Theophylline, Theobromine and Adenine

Mahmoud A. Alawi, Safaa Al-Shawa

Abstract


An HPLC method with electrochemical detection in the oxidation mode is developed for the determination of caffeine, theophylline, theobromine, and adenine. The method includes a separation step on RP-C8 column using acetonitrile and 0.05M KH2PO4 buffer solution in a ratio of 10:90% (v/v) as a mobile phase. Electrochemical detection was conducted on a Glassy Carbon Electrode (GCE) and on a self-made Iodine-coated platinum (Pt-I) electrode. The optimum working potential for GCE used with the Ag/AgCl (3M KCl) as reference electrode was found to be at +1.45 V, whereas that for the Pt-I electrode was found to be at +1.55 V.
The Pt-I electrode shows equal or better sensitivity compared to GCE.
The developed method shows a good applicability (sensitivity, selectivity and reproducibility) for real samples of coffee and tea.

Keywords


HPLC/ELCD, Caffeine, Theophylline, Theobromine, Adenine.

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