Determination of Eight Kinds of Catechins in Bottled Green-tea Drinks by HPLC on a Cholesteryl Group Staionary Phase Column

Eight kinds of catechins are well known because of their antioxidant activity and chemopreventive effects against cancers. The determination of eight kinds of catechins {GC: (−)-gallocatechin; EGC: (−)-epigallocatechin; C: (+)-catechin; EC: (−)-epicatechin; EGCg: (−)-epigallocatechin gallate; GCg: (−)-gallocatechin gallate; ECg: (−)-epicatechin gallate; CG: (−)-catechin gallate} in bottled green tea drinks by high-performance liquid chromatography (HPLC) with an ultraviolet detector (UV) on a cholesteryl group stationary phase column has been developed. This analytical method provides high linearity of the calibration curve as well as both repeatability and reproducibility. The correlation coefficient of the working curve of calibration were estimated to be from 0.9998 to 0.9987 for eight kinds of catechins in the concentration range from 5 mg L−1 to 150 mg L−1. The limits of detection (LOD) calculated on 3σ at 10 mg L−1 were 0.39 mg L−1 for GC, 0.74 mg L−1 for EGC, 0.07 mg L−1 for C, 0.33 mg L−1 for EC, 0.28 mg L−1 for EGCg, 0.35 mg L−1 for GCg, 0.18 mg L−1 for ECg, and 0.19 mg L−1 for CG. The limits of quantification (LOQ) calculated on 10σ at 10 mg L−1 were 1.29 mg L−1 for GC, 2.48 mg L−1 for EGC, 0.24 mg L−1 for C, 1.09 mg L−1 for EC, 0.94 mg L−1 for EGCg, 1.17 mg L−1 for GCg, 0.62 mg L−1 for ECg, and 0.65 mg L−1 for CG. Good results (the recoveries were 85.5–109.6% and the relative standard deviations were 2.5–4.9%) were obtained in recovery tests by using bottled green tea drinks. This proposed method could be successfully applied to the determination of eight kinds of catechins in bottled green tea drinks.