Rapid Determination of Eight Catechins in Bottled Green Tea Drinks using Isocratic Elution Method/RP-HPLC-UV

Abstract

An accurate, simple and rapid isocratic elution method for the simulutaneous determination of eight catechins in bottled green tea drinks using reversed-phase (RP) high performance liquid chromatography (HPLC) with ultraviolet detecter (UV) and short column (100 mm×4.6 mm i. d., particle diameter 3 μm) has been studied. As a result, good linearity of the calibration curve were obtained in the concentration range from 1 mg l-1 to 100 mg l-1 (|r| =0.9998-0.9974) . The detection limits based on S/N=3 were 0.62 mg l-1 for (-) -gallocatechin (GC), 0.78 mg l-1 for (-) -epigallocatechin (EGC), 0.59 mg l-1for (+) -catechin (C), 0.38 mg l-1 for 7- (β-hydroxyethyl) theophylline, 0.42 mg l-1 for (-) -epigallocatechin gallate (EGCg), 0.57 mg l-1 for (-) -epicatechin (EC), 0.48 mg l-1 for (-) -gallocatechin gallate (GCg), 0.40 mg l-1 for (-) -epicatechin gallate (ECg), and 0.43 mg l-1 for (-) -catechin gallate (Cg) in 5 μl injection. The eight catechins and 7- (β-hydroxyethyl) theophylline were separated by an isocratic elution method within 30 min. This Isocratic elution method could be successfully applied to the rapid determination of eight catechins in bottled green tea drinks.