DETERMINATION OF CATECHINS IN TEA BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH A GRAPHENE OXIDE-COATED CAPILLARY

A novel approach was developed for the determination of four catechins, (-)-epigallocatechin gallate, (-)-epigallocatechin, (-)-gallocatechin gallate, and (-)-epicatechin, in tea by micellar electrokinetic chromatography (MEKC) using an acidic phosphate buffer (40 mM, 100 mM sodium dodecyl sulfate, and 30% methanol, pH 3.0). The linear dynamic ranges for the catechins were between 25 and 250 μg/mL, and the graphene oxide-coated capillary offered satisfactory accuracy, precision, and limits of detection. The developed method was employed for the determination of catechins in tea.