Direct determination of caffeine in crude caffeine by gas chromatography

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  • ガスクロマトグラフィーによる粗カフェイン中のカフェインの直接定量
  • ガス クロマトグラフィー ニヨル ソ カフェインチュウ ノ カフェイン ノ チ

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Abstract

A new method for the determination of caffeine in crude caffeine imported as industrial raw material has been developed. Gas chromatographic analysis was carried out on a Shimadzu GC5A PF gas chromatograph equipped with an FID and a digital integrater ITG-2A. Sample solution was prepared by dissolving (0.30.4)g of crude caffeine and 0.1 g of phenacetine as internal standard in 10 ml of CHCl3. A 0.1 μl of the filtrate was applied to gas chromatograph. Caffeine, theobromine and theophylline were separated by g.c. on a glass column (4 m×3 mm) packed with 2% silicnoe OV-17 on chromosorb GAW DMCS at 225 °C. The relation between weight ratio of caffeine to phenacetine and its area ratio was rectilinear in the range of weight ratio from 1.0 to 3.6. The reproducibility within above range of concentration was below 0.7% as coefficient of variation. From the results of the examination by addition method, the recoveries of caffeines added to crude caffeine are 99.0 to 100.4%. Impurities like theobromine, theophylline, hydrocarbons, lipids, sugars and amino acids which accompanied with crude caffeine from natural origin do not interfere. Thus, direct determination of caffeine in crude caffeine was possible in this method.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 25 (5), 323-327, 1976

    The Japan Society for Analytical Chemistry

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