2.3. Polyamide column chromatography
For pretreatment of polyamide SC 6, particle size 0.05–0.16 mm, (Macherey & Nagel, Dueren, Germany) see Engelhardt et al. (1992). A glass column (14 cm 2.5 cm i.d.) was filled with 10 cm-layer polyamide and conditioned with 250 mL of deionized water. Tea extract (25 mL) was applied to the column. After washing with
100 mL of water, the phenolic compounds were eluted with 250 mL of methanol. The methanol was removed using a rotary evaporator, and the residue was transferred with 4 mL of N, N-dimethylformamide (DMF) to a 10 mL measuring flask and made up to volume with water. DMF is known to be a good solvent for FOG. After membrane filtration (0.2 lm) the solution was ready