Sodium Alginate
(soe' dee um al' ji nate).
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Alginic acid, sodium salt;    
Sodium alginate     [9005-38-3].
Sodium Alginate is the purified carbohydrate product extracted from brown seaweeds by the use of dilute alkali. It consists chiefly of the sodium salt of Alginic Acid, a polyuronic acid composed of -d-mannuronic acid residues linked so that the carboxyl group of each unit is free while the aldehyde group is shielded by a glycosidic linkage. It contains NLT 90.8% and NMT 106.0% of sodium alginate of average equivalent weight 222.00, calculated on the dried basis.
•  A.
Sample solution:  A solution (1 in 100)
Analysis:  To 5 mL of Sample solution add 1 mL of calcium chloride TS.
Acceptance criteria:  A voluminous, gelatinous precipitate is formed immediately.
•  B.
Sample solution:  A solution (1 in 100)
Analysis:  To 10 mL of Sample solution add 1 mL of 4 N sulfuric acid.
Acceptance criteria:  A heavy, gelatinous precipitate is formed.
•  Alginates
Sample:  250 mg
Analysis:  Each mL of 0.2500 N sodium hydroxide consumed is equivalent to 27.75 mg of sodium alginate.
Acceptance criteria:  90.8%–106.0% on the dried basis
•  Arsenic, Method II 211 NMT 1.5 ppm
•  Lead 251
Standard solution:  5 mL of Diluted Standard Lead Solution
Test preparation:  Add 1.0 g to 20 mL of nitric acid in a 250-mL conical flask, mix, and heat carefully until the Sodium Alginate is dissolved. Continue heating until the volume is reduced to 7 mL. Cool rapidly to room temperature, transfer to a 100-mL volumetric flask, and dilute with water to volume.
Analysis:  Use 50 mL of the Test preparation, and proceed as directed in the chapter, using 15 mL of ammonium citrate solution, 3 mL of potassium cyanide solution, and 0.5 mL of hydroxylamine hydrochloride solution. After the first dithizone extraction, wash the combined chloroform layers with 5 mL of water, discarding the water layer and continuing in the usual manner by extracting with 20 mL of 0.2 N nitric acid.
Acceptance criteria:  Contains NMT 5 µg of lead (corresponding to NMT 10 ppm)
•  Heavy Metals, Method II 231
[Note—Conduct the ignition in a platinum crucible, and use nitric acid in place of sulfuric acid to wet the test specimen. ]
Acceptance criteria:  NMT 40 ppm
•  Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total bacterial count does not exceed 200 cfu/g, and the tests for Salmonella species and Escherichia coli are negative.
•  Loss on Drying 731: Dry a sample at 105 for 4 h: it loses NMT 15.0% of its weight.
•  Articles for Botanical Origin, Total Ash 561: Proceed as directed in Methods of Analysis, carefully igniting 3 g in a tared platinum dish, until the residue is thoroughly carbonized (5 min), and then igniting in a muffle furnace at a temperature of 800 ± 25 until the carbon is completely burned off (approximately 75 min).
Acceptance criteria:  18.0%–27.0% of ash on the dried basis
•  Packaging and Storage: Preserve in tight containers.
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Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
61 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
(GCM2010) General Chapters - Microbiology
62 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
(GCM2010) General Chapters - Microbiology
USP35–NF30 Page 1950