» Activated Charcoal is the residue from the destructive distillation of various organic materials, treated to increase its adsorptive power.
Packaging and storage Preserve in well-closed containers.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 It meets the requirements of the tests for absence of Salmonella species and Escherichia coli.
Reaction Boil 3.0 g with 60 mL of water for 5 minutes, allow to cool, restore the original volume by the addition of water, and filter: the filtrate is colorless and is neutral to litmus.
Loss on drying 731 Dry it at 120 for 4 hours: it loses not more than 15.0% of its weight.
Residue on ignition 281: not more than 4.0%, a 0.50-g test specimen being used.
Acid-soluble substances Boil 1.0 g with a mixture of 20 mL of water and 5 mL of hydrochloric acid for 5 minutes, filter into a tared porcelain crucible, and wash the residue with 10 mL of hot water, adding the washing to the filtrate. To the combined filtrate and washing add 1 mL of sulfuric acid, evaporate to dryness, and ignite to constant weight: the residue weighs not more than 35 mg (3.5%).
Chloride 221 A 10-mL portion of the filtrate obtained in the test for Reaction shows no more chloride than is contained in 1.5 mL of 0.020 N hydrochloric acid (0.2%).
Sulfate 221 A 10-mL portion of the filtrate obtained in the test for Reaction shows no more sulfate than is contained in 1.0 mL of 0.020 N sulfuric acid (0.2%).
Sulfide Place 0.50 g in a small conical flask, add 20 mL of water and 5 mL of hydrochloric acid, and boil gently: the escaping vapors do not darken paper moistened with lead acetate TS.
Cyanogen compounds Place a mixture of 5 g of Activated Charcoal, 50 mL of water, and 2 g of tartaric acid in a distilling flask connected to a condenser provided with a tightly fitting adapter, the end of which dips below the surface of a mixture of 2 mL of 1 N sodium hydroxide and 10 mL of water, contained in a small flask surrounded by ice. Heat the mixture in the distilling flask to boiling, and distill about 25 mL. Dilute the distillate with water to 50 mL, and mix. To 25 mL of the diluted distillate add 12 drops of ferrous sulfate TS, heat the mixture almost to boiling, cool, and add 1 mL of hydrochloric acid: no blue color is produced.
Heavy metals 231 Boil 1.0 g with a mixture of 20 mL of 3 N hydrochloric acid and 5 mL of bromine TS for 5 minutes, filter, and wash the charcoal and the filter with 50 mL of boiling water. Evaporate the filtrate and washing to dryness, and to the residue add 1 mL of 1 N hydrochloric acid, 20 mL of water, and 5 mL of sulfurous acid. Boil the solution until all of the sulfur dioxide is expelled, filter if necessary, and dilute with water to 50 mL. To 20 mL of the solution add water to make 25 mL: the limit is 0.005%.
Uncarbonized constituents Boil 0.25 g with 10 mL of 1 N sodium hydroxide for 5 seconds, and filter: the filtrate is colorless.
Alkaloids Shake 1 g of Activated Charcoal, previously dried at 120 for 4 hours, with a solution of 100 mg of strychnine sulfate in 50 mL of water for 5 minutes, and filter through a dry filter, rejecting the first 10 mL of the filtrate. To a 10-mL portion of the subsequent filtrate add 1 drop of hydrochloric acid and 5 drops of mercuric-potassium iodide TS: no turbidity is produced.
Dyes Pipet 50 mL of methylene blue solution (1 in 1000) into each of two glass-stoppered, 100-mL flasks. Add to one flask 250 mg, accurately weighed, of Activated Charcoal, insert the stopper in the flask, and shake for 5 minutes. Filter the contents of each flask through a dry filter, rejecting the first 20 mL of each filtrate. Pipet 25-mL portions of the remaining filtrates into two 250-mL volumetric flasks. Add to each flask 50 mL of sodium acetate solution (1 in 10), mix, and add from a buret 35.0 mL of 0.1 N iodine VS, swirling the mixture during the addition. Insert the stoppers in the flasks, and allow them to stand for 50 minutes, shaking them vigorously at 10-minute intervals. Dilute each mixture with water to volume, mix, allow to stand for 10 minutes, and filter through dry filters, rejecting the first 30 mL of each filtrate. Titrate the excess iodine in a 100-mL aliquot of each subsequent filtrate with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Calculate the number of mL of 0.1 N iodine consumed in each titration: the difference between the two volumes is not less than 0.7 mL.
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USP32NF27 Page 1882