Carboxymethylcellulose Calcium
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
Carboxymethylcellulose Calcium
Add the following:
Portions of this monograph that are national USP text, and are not part of the harmonized text, are marked with symbols (⧫) to specify this fact.▲ (NF 1-Aug-2024)
Cellulose carboxymethyl ether calcium salt
CAS RN®: 9050-04-8.
1 DEFINITION
Carboxymethylcellulose Calcium is the calcium salt of a polycarboxymethyl ether of cellulose.
2 IDENTIFICATION
A.
Sample solution: Shake thoroughly 0.1 g of Carboxymethylcellulose Calcium with 10 mL of water, followed by 2 mL of 1 N sodium hydroxide, and allow to stand for 10 min. [Note—Save the unused portion of the Sample solution for use in Identification B and C.]
Analysis: To 1 mL of the Sample solution add water to make 5 mL. To 1 drop of the resulting solution, add 0.5 mL of chromotropic acid TS, and heat in a water bath for 10 min.
Acceptance criteria: A red-purple color develops.
B.
Analysis: Shake 5 mL of the Sample solution prepared in Identification A with 10 mL of acetone.
Acceptance criteria: A white, flocculent precipitate is formed.
C.
Analysis: Shake 5 mL of the Sample solution prepared in Identification A with 1 mL of ferric chloride TS.
Acceptance criteria: A brown, flocculent precipitate is formed.
Change to read:
D. Identification Tests—General 〈191〉, Chemical Identification Tests, Calcium
Analysis: Ignite 1 g to ash, dissolve the residue in 10 mL of water and 5 mL of 6 N acetic acid, and filter, if necessary. Boil the filtrate, cool, ▲add 2 drops of methyl red TS,▲ (NF 1-Aug-2024) and neutralize with 6 N ammonium hydroxide. ▲Add 3 N hydrochloric acid dropwise until the solution is acid to the indicator. Upon the addition of ammonium oxalate TS, a white precipitate is formed. This precipitate is insoluble when 6 N acetic acid is added but dissolves in hydrochloric acid.▲ (NF 1-Aug-2024)
Acceptance criteria: Meets the requirements
3 IMPURITIES
Residue on Ignition 〈281〉: 10.0%–20.0%; use 1.0 g, previously dried
Chloride and Sulfate 〈221〉, Chloride
Sample stock solution: Shake thoroughly 0.80 g with 50 mL of water, dissolve in 10 mL of 1 N sodium hydroxide, and add water to make 100 mL. [Note—Retain a portion of the Sample stock solution for use in the test for Sulfate.]
Sample solution: Heat 20 mL of the Sample stock solution with 10 mL of 2 N nitric acid in a water bath until a flocculent precipitate is formed, cool, centrifuge, and remove the supernatant. Wash the precipitate with three 10-mL portions of water by centrifuging each time, combine the supernatant and the washings, add water to make 100 mL, and mix.
Acceptance criteria: A 25-mL portion of the Sample solution shows no more chloride than is contained in 0.20 mL of 0.020 N hydrochloric acid (0.36%).
Change to read:
Chloride and Sulfate 〈221〉, Sulfate
[Note—This test is only necessary if sulfuric acid is utilized in the manufacturing process, as indicated on the labeling.]▲ (NF 1-Aug-2024)
Sample solution: Heat 10 mL of the Sample stock solution prepared in the test for Chloride with 1 mL of hydrochloric acid in a water bath until a flocculent precipitate is formed. Cool, centrifuge, and remove the supernatant. Wash the precipitate with three 10-mL portions of water by centrifuging each time, combine the supernatant and the washings, add water to make 100 mL, and mix.
Acceptance criteria: A 25-mL portion of the Sample solution shows no more sulfate than is contained in 0.21 mL of 0.020 N sulfuric acid (1.0%).
4 SPECIFIC TESTS
Alkalinity: Shake thoroughly 1.0 g with 50 mL of freshly boiled and cooled water, and add 2 drops of phenolphthalein TS: no red color develops.
Change to read:
Loss on Drying 〈731〉: Dry ▲1.0 g of▲ (NF 1-Aug-2024) a sample at 105° for 4 h: it loses NMT 10.0% of its weight.
5 ADDITIONAL REQUIREMENTS
Change to read:
▲⧫ ▲ (NF 1-Aug-2024) Packaging and Storage: Preserve in tight containers.▲ ▲ (NF 1-Aug-2024)
Add the following:
▲Labeling: Label to indicate if sulfuric acid is utilized in the manufacturing process.▲ (NF 1-Aug-2024)
