Determination of tea fermentation degree by a rapid micellar electrokinetic chromatography
2010
Hsiao, Hsien-Yi | Chen, Richie L.C. | Cheng, Tzong-Jih
A micellar electrokinetic capillary electrophoresis (MEKC) method was used to rapidly determine seven tea catechins, three xanthines, gallic acid, vitamin C, theanine and theaflavin in tea. All the compounds were successfully separated (20kV) within 8min of migration in the running buffer (pH 7.0) containing 10mM phosphate, 4mM sodium tetraborate, 45mM SDS and 0.5% ethanol. The linear dynamic ranges for polyphenols were from 2.5 (S/N >8) to 100μg/ml. As revealed by the electropherograms, tea catechins were found to be depleted along with the indoor withering process for making pouching tea, and the fermentation degree can be quantified. The results were compared with the redox potentials of tea infusions.
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