Gallic acid (C7H6O5, MW= 170.12, >98% pure) and ethanol were purchased from Sigma–Aldrich (Germany). Gallic acid was used without prior treatment, but stored in a dessicator with P2O5 once the bottle has been opened. Absolute Ethanol was of analytical grade (C2H6O, purity = 99.8%, MW= 46.07, d = 0.79 g/mL). Distilled water (conductivity around 1.5 lS cm1) has been used.