Analysis of theanine, glutamic acid and aspartic acid in green tea by capillary tube isotachophoresis

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Other Title
  • 細管式等速電気泳動法による緑茶中のテアニン，グルタミン酸，アスパラギン酸の分析
  • サイカンシキ トウソク デンキ エイドウホウ ニヨル リョクチャチュウ ノ テ

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Description

Theanine (L-glutamic acid-γ-ethylamide, The), aspartic acid (Asp) and glutamic acid (Glu) in green tea were analyzed by means of capillary tube isotachophoresis, with an intention to find a simpler analytical method, and the analytical conditions, such as electrolyte systems, pH and capillary tube length, have been investigated. Three amino acids, The, Asp, and Glu, which are typical amino acids in green tea, were separated using four electrolytes having pH values of 3.88, 6.21, 7.55 and 8.65 and then determined quantitatively. A combination of a leading electrolyte of pH 3.88, containing 0.01M hydrochloride (HCl), β-alanine and polyvinyl alcohol (PVA), and a terminal electrolyte, containing 0.01M caproic acid, gives the best result in analysis of acidic amino acids, Asp and Glu, because the combination gives the largest mobility difference under the condition. As The does not migrate toward the anode under an acidic or neutral condition, it was analyzed under a basic condition, that is, by the use of a combination of a leading electrolyte of pH 7.55 or 8.65, containing 0.01M HCl, ammediol (2-amino-2-methyl-1, 3-propanediol) and PVA, and a terminal electrolyte containing 0.01M β-alanine and barium hydroxide. Some other components which were contained in tea extract and had similar mobilities to The in this electrolyte system were separated satisfactorily by the use of a longer capillary tube (40 cm).

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 26 (10), 701-705, 1977

    The Japan Society for Analytical Chemistry

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