Simultaneous Determination of 5 Active Components in Tea by Capillary Zone Electrophoresis

Capillary zone electrophoresis (CZE) was applied to the determination of 5 active components (i.e., protocatechuic aldehyde, protocatechic acid, epicatechin, DL-catechin and quercitin) in tea. Efficient separation was attained by using the un-coated adaptive quartz capillary column (57 cm×75 μm, effective length 50 cm) and the electrophoretic medium of a buffer mixture, containing 10 mmol·L-1 Na2B4O7, 5 mmol·L-1 β-CD, 15% (φ) acetonitrile and 2% (φ) ethylene glycol (acidity adjusted to pH 9.11) with separation voltage of 20 kV. Linearity ranges were found between 8.152 5-217.4 mg·L-1 (for protocatechuic aldehyde), 8.152 5-217.4 mg·L-1 (for protocatechic acid), 2.174-217.4 mg·L-1 (for epicatechin), 1.739-150.0 mg·L-1 (for DL-catechin) and 1.739-150.0 mg·L-1 (for quercitin). The proposed method was used for determination of the 5 components in tea samples, giving values of recovery and RSD′s (n=5) in the ranges of 94.6%-107% and 0.17%-4.4% respectively.