Separation of catechins and O-methylated (−)-epigallocatechin gallate using polyamide thin-layer chromatography

• Via TLC a simultaneous determination of catechins and O-methylated EGCG was realized.
• O-methylated EGCG were detected screening teas or tea cultivars rich in EGCG3′′Me or EGCG4′′Me.
• Sample preparation was simple.
• Small amounts of organic solvent are needed in this method.

Thin-layer chromatography (TLC) method for the separation and quantitative determination of seven related compounds: (+)-catechin (C), (−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me) and (−)-epigallocatechin- 3-O-(4-O-methyl) gallate (EGCG4″Me) has been developed. The above-mentioned seven compounds have been resolved using polyamide TLC plates using a double-development with methanol followed by acetone/acetic acid (2:1, v/v). In addition, separation of the phenolic acids namely gallic acid, chlorogenic acid, and caffeic acid was achieved using the same solvent system. The applicability of the method was checked by screening of extracts of green, black, oolong, white tea and tea cultivars leaves.