Investigation of the Amount of Tannic Acid in Bark Oak (Quercus castanifolia)

In order to perform a qualitative and quantitative investigation on tannic acid content in Oak bark، the bark samples were collected from Educational Forest of Gorgan Agricatural Science and Natural Resources University. Solvents were used in laboratory to extract tannin and were considered as variables. Regarding diversity of bark components، Tappi Test Method (T264-om-88) was used to determin extractives contest. Twenty grams dry material was placed in a soxhelt. Extracted material with hot water، methanol and water- methanol (1:1) solvent were 25±2، 20±2 and 18±2 percents respectively. Tannic acid existance in extracts was determined using High Performance Liquid Choromatography (HPLC) and types of bonds were determined using FT-IR. Results showed that water-methanol solvent was the best solvent for extracting tannin. the amount of extracted tannic acid in maximum wavelength of 250 nm and using gradient system، in solvent water-methanol، methanol and hot water solvent were 70±2، 30±2 and 5±2 precents، respectively. Amount of tannin in the bark using solvent water-methanol was determined to be 14 perecents that was the highest amount.