[Determination of catechins in grape seeds by capillary electrophoresis].
A capillary zone electrophoresis (CZE) method has been developed for the determination of four pharmacologically active catechins in grape seed. The components analyzed were (+)-catechin, (-)-epicatechin, epigallocatechin and epicatechin gallate. Separation was achieved by using a mixed buffer of 0.02 mol/L borate and 0.005 mol/L phosphate at pH 10.0 as background electrolyte and an uncoated fused silica capillary with 50 microns i.d. x 375 microns o.d. (effective length 41.5 cm) maintained at 25 degrees C. The applied voltage was 25 kV, and detection was performed by DAD at wavelength of 210 nm. By using proposed CZE method, four catechins were well separated within only 10 minutes with the repeatability of < 1% RSD for migration time and < 5% RSD for peak area. Correlation coefficients better than 0.995 were obtained within the concentration range from 0.005 g/L to 0.5 g/L for the four analytes studied with the detection limit of 3 mg/L-10 mg/L. The contents of these compounds in ten species of grape seeds cultivated in China were successfully determined.