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7.21H DETERMINATION OF TANNINS

          Sample preparation Place the prescribed quantity of the substance, previously powdered and accurately weighed as specified in the monograph, in a 250-mL conical flask. Add 150 mL of water and heat on a water-bath for 30 minutes. Cool in running water, transfer the mixture quantitatively to a 250-mL volumetric flask with water and dilute to volume with water. Allow the solids to settle and filter.

          Determination of total water-extractives Evaporate 50.0 mL of the Sample preparation and dry the residue at 105° for 4 hours and weigh (T1).

          Determination of water-extractives not bound with hide powder To 80.0 mL of the Sample preparation, add 6.00 g of hide powder and shake well for 60 minutes. Filter and evaporate 50.0 mL of the filtrate to dryness. Dry the residue at 105° for 4 hours and weigh (T2).

          Determination of water-solubles of hide powder To 6.00 g of hide powder, add 80.0 mL of water and shake well for 60 minutes. Filter and evaporate 50.0 mL of the filtrate to dryness. Dry the residue at 105° for 4 hours and weigh (T0).

          Calculation Calculate the percentage of tannins from the expression:

          where W is the weight in g of the substance taken, calculated on the dried basis.

APPENDICES • 7.21H DETERMINATION OF TANNINS
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หมายเหตุ / Note : THP 2021 Page 929