Tannic Acid HPLC Method 1

PAPER 1. Using hexane, methanol-tetrahydrofuran Normal phase A 25 x 0.46 cm column packed with 5-pm ROSiL (a spherical silica gel from Alltech-RSL) was used. The solvent employed were (A) hexane (Burdick & Jackson Labs.) and (B) methanol-tetrahydrofuran (75:25) (both from Burdick & Jackson Labs.). To solvent B, 0.25% of pure citric acid was added. The gradient used was 80% A and 20% B at 0 min c..