Alginic Acid

Alginic acid.
Alginic acid [9005-32-7].
» Alginic Acid is a hydrophilic colloidal carbohydrate extracted with dilute alkali from various species of brown seaweeds (Phaeophyceae).
Packaging and storage— Preserve in well-closed containers.
A: To 5 mL of a 1 in 150 solution in 0.1 N sodium hydroxide add 1 mL of calcium chloride TS: a voluminous, gelatinous precipitate is formed.
B: To 5 mL of a 1 in 150 solution in 0.1 N sodium hydroxide add 1 mL of 4 N sulfuric acid: a heavy, gelatinous precipitate is formed.
C: To about 5 mg in a test tube add 5 mL of water, 1 mL of a freshly prepared 1 in 100 solution of 1,3-naphthalenediol in alcohol, and 5 mL of hydrochloric acid. Heat the mixture to boiling, boil gently for 3 minutes, then cool to about 15. Transfer the contents of the test tube to a 30-mL separator with the aid of 5 mL of water, and extract with 15 mL of isopropyl ether: the isopropyl ether extract exhibits a deeper purplish hue than that from a blank, similarly prepared.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 The total bacterial count does not exceed 200 per g, and the tests for Salmonella species and Escherichia coli are negative.
pH 791: between 1.5 and 3.5, in a 3 in 100 dispersion in water.
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 15.0% of its weight.
Total ash 561 Proceed as directed for Total Ash under Articles of Botanical OriginMethods of Analysis 561, carefully igniting about 4 g of Alginic Acid, accurately weighed, in a tared platinum dish, until the residue is thoroughly carbonized (about 5 minutes), and then igniting in a muffle furnace at a temperature of 800 ± 25 until the carbon is completely burned off (20 to 35 minutes): not more than 4.0% of ash is found.
Lead— Add 1.0 g to 20 mL of nitric acid in a 250-mL conical flask, mix, and heat carefully until the Alginic Acid is dissolved. Continue heating until the volume is reduced to about 7 mL. Cool rapidly to room temperature, transfer to a 100-mL volumetric flask, and dilute with water to volume. A 50.0-mL portion of this solution contains not more than 5 µg of lead (corresponding to not more than 0.001%) when tested according to the test for Lead 251, 15 mL of ammonium citrate solution, 3 mL of potassium cyanide solution, and 500 µL of hydroxylamine hydrochloride solution being used. 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.
Heavy metals, Method II 231: 0.004%, a platinum crucible being used for the ignition and nitric acid being used in place of sulfuric acid to wet the test specimen.
Acid value 401 Suspend about 1 g of Alginic Acid, accurately weighed, in a mixture of 50 mL of water and 30.0 mL of calcium acetate solution (11 in 250). Shake thoroughly, allow the mixture to stand for 1 hour, add phenolphthalein TS, and then titrate the liberated acetic acid with 0.1 N sodium hydroxide VS. Perform a blank determination, and calculate the acid value taken by the formula:
5.611(A B) / W
in which 5.611 is one-tenth the molecular weight of potassium hydroxide; A and B are the volumes, in mL, of 0.100 N sodium hydroxide consumed in the titrations of the test preparation and blank, respectively; and W is the weight, in g, of Alginic Acid taken. The acid value of Alginic Acid, calculated on the dried basis, is not less than 230.
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Topic/Question Contact Expert Committee
Monograph Hong Wang, Ph.D.
(EM205) Excipient Monographs 2
61 Radhakrishna S Tirumalai, Ph.D.
Senior Scientist
(MSA05) Microbiology and Sterility Assurance
62 Radhakrishna S Tirumalai, Ph.D.
Senior Scientist
(MSA05) Microbiology and Sterility Assurance
USP32–NF27 Page 1159
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.