title: Determination of adenine, caffeine, theophylline and theobromine by HPLC with amperometric detection.
abstract: A relatively simple method for quantifying caffeine, theobromine, theophylline and adenine by HPLC with amperometric detection was developed. A C(18)-column and an isocratic elution with phosphate buffer pH 3.5/methanol (90 : 10) were employed for the chromatographic separation of the investigated compounds. The optimal detection potential was +1.4 V. The limits of detection were 0.4 ng for adenine, 1 ng for theophylline and 2.5 ng for caffeine and theobromine. The method was applied to the determination of these purine alkaloids in beverages, tea, coffee and cacao. The determination was carried out directly or after solid-phase extraction.
authors.affiliation: Fachbereich Chemie der Universität Kaiserslautern und Abteilung für Anorganische und Analytische Chemie der Universität Trier, Postfach 3825, D-54228, Trier, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Meyer
authors.forename: T
authors.initials: T
authors.lastname: Ngiruwonsanga
authors.forename: G
authors.initials: G
authors.lastname: Henze