Determination of Caffeine, Theobromine, and Theophylline in Standard Reference Material 2384, Baking Chocolate, Using Reversed-Phase Liquid Chromatography

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• 作者：Jeanice Brown Thomas ; James H. Yen ; Michele M. Schantz ; Barbara J. Porter ; and Katherine E. Sharpless
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2004
• 出版时间：June 2, 2004
• 年：2004
• 卷：52
• 期：11
• 页码：3259 - 3263
• 全文大小：73K
• 年卷期：v.52,no.11(June 2, 2004)
• ISSN：1520-5118

文摘

A rapid and selective isocratic reversed-phase liquid chromatographic method has been developedat the National Institute of Standards and Technology to simultaneously measure caffeine,theobromine, and theophylline in a food-matrix standard reference material (SRM) 2384, BakingChocolate. The method uses isocratic elution with a mobile phase composition (volume fractions) of10% acetronitrile/90% water (pH adjusted to 2.5 using acetic acid) at a flow rate of 1.5 mL/min withultraviolet absorbance detection (274 nm). Total elution time for these analytes is less than 15 min.Concentration levels of caffeine, theobromine, and theophylline were measured in single 1-g samplestaken from each of eight bars of chocolate over an eight-day period. Samples were defatted withhexane, and -hydroxyethyltheophylline was added as the internal standard. The repeatability forthe caffeine, theobromine, and theophylline measurements was 5.1, 2.3, and 1.9%, respectively.The limit of quantitation for all analytes was <100 ng/mL. The measurements from this method wereused in the value-assignment of caffeine, theobromine, and theophylline in SRM 2384.Keywords: Standard reference material; caffeine; theobromine; theophylline; chocolate; liquid chromatography; reversed-phase