Activated Charcoal
DEFINITION
Activated Charcoal is the residue from the destructive distillation of various organic materials, treated to increase its adsorptive power.
IMPURITIES
• Acid-Soluble Substances
Sample:
1.0 g
Analysis:
Boil the Sample with a mixture of 20 mL of water and 5 mL of hydrochloric acid for 5 min. 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.
Acceptance criteria:
The residue weighs NMT 35 mg (NMT 3.5%).
• Chloride and Sulfate, Chloride 
221
221
Sample solution:
A 10-mL portion of the filtrate obtained in the test for Reaction
Acceptance criteria:
The Sample solution shows no more chloride than is contained in 1.5 mL of 0.020 N hydrochloric acid (NMT 0.2%).
• Chloride and Sulfate, Sulfate 221
221
Sample solution:
A 10-mL portion of the filtrate obtained in the test for Reaction
Acceptance criteria:
The Sample solution shows no more sulfate than is contained in 1.0 mL of 0.020 N sulfuric acid (NMT 0.2%).
• Sulfide
Sample:
0.50 g
Analysis:
Place the Sample in a small conical flask. Add 20 mL of water and 5 mL of hydrochloric acid, and boil gently.
Acceptance criteria:
The escaping vapors do not darken paper moistened with lead acetate TS.
• Cyanogen Compounds
Sample:
5 g
Analysis:
Place the Sample, 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.
Acceptance criteria:
No blue color is produced.
• Heavy Metals 231
231
Sample:
1.0 g
Test preparation:
Boil the Sample with a mixture of 20 mL of 3 N hydrochloric acid and 5 mL of bromine TS for 5 min. 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.
Acceptance criteria:
NMT 50 ppm
• Uncarbonized Constituents
Sample:
0.25 g
Analysis:
Boil the Sample with 10 mL of 1 N sodium hydroxide for 5 s, and filter.
Acceptance criteria:
The filtrate is colorless.
SPECIFIC TESTS
• Adsorptive Power
Alkaloids
Sample:
1 g, previously dried at 120
for 4 h
for 4 h
Analysis:
Shake the Sample with a solution of 100 mg of strychnine sulfate in 50 mL of water for 5 min, 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.
Acceptance criteria:
No turbidity is produced.
Dyes
Sample:
250 mg
Analysis:
Pipet 50 mL of methylene blue solution (1 in 1000) into each of two glass-stoppered, 100-mL flasks. Add the Sample to one of the flasks, insert the stopper in the flask, and shake for 5 min. 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 min, shaking them vigorously at 10-min intervals. Dilute each mixture with water to volume, mix, allow to stand for 10 min, 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 mL of 0.1 N iodine consumed in each titration.
Acceptance criteria:
The difference between the two volumes is NLT 0.7 mL.
• 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.
61 and Tests for Specified Microorganisms 62:
It meets the requirements of the tests for absence of Salmonella species and Escherichia coli.
• Reaction
Sample:
3.0 g
Analysis:
Boil the Sample with 60 mL of water for 5 min. Allow to cool, restore the original volume by the addition of water, and filter.
Acceptance criteria:
The filtrate is colorless and is neutral to litmus.
• Loss on Drying 731:
Dry a sample at 120 for 4 h: it loses NMT 15.0% of its weight.
731:
Dry a sample at 120 for 4 h: it loses NMT 15.0% of its weight.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Elena Gonikberg, Ph.D.
Principal Scientific Liaison 1-301-816-8251 |
(SM32010) Monographs - Small Molecules 3 |
| 61 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| 62 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
USP35–NF30 Page 2604