Alginic Acid, Grade : USP/E-400

Description

Alginic acid occurs in filamentous, grainy, granular and powdered forms. It is a white to yellowish brown and nearly odorless

Industries

Alginates are used in a variety of industries, such as Medical and Clinical, Pharmaceutical, Food and Beverage, Arts and Craft, Textile, Fertilizer, Paint and dye, Paper Manufacturing and print or the leisure and cosmetics industry. 

Definition

Linear glucuronoglycan consisting mainly of β-(1-4) linked D-mannuronic and α-(1-4) linked L-guluronic acid units in pyranose ring form. Hydrophilic colloidal carbohydrate extracted by the use of dilute alkali from strains of various species of brown seaweeds (Phaeophyceae)

Einecs: 232-680-1

Chemical formula: (C 6 H 8 O 6 ) n

Molecular weight: 10 000-600 000 (typical average)

Assay

Alginic acid yields, on the anhydrous basis, not less than 20 % and not more than 23 % of carbon dioxide (CO 2 ), equivalent to not less than 91 % and not more than 104,5 % of alginic acid (C 6 H 8 O 6 ) n (calculated on equivalent weight basis of 200)

Solubility: Insoluble in water and organic solvents, slowly soluble in solutions of sodium carbonate, sodium hydroxide, and trisodium phosphate

Calcium chloride precipitation test: To a 0,5 % solution of the sample in 1 M sodium hydroxide solution add one-fifth of its volume of a 2,5 % solution of calcium chloride. A voluminous, gelatinous precipitate is formed. This test distinguishes alginic acid from acacia gum, sodium carboxymethyl cellulose, carboxymethyl starch, carrageenan, gelatin, gum ghatti, karaya gum, locust bean gum, methylcellulose, and tragacanth gum.

Ammonium sulfate precipitation test: To a 0,5 % solution of the sample in 1 M sodium hydroxide solution add one half of its volume of a saturated solution of ammonium sulfate. No precipitate is formed. This test distinguishes alginic acid from agar, sodium carboxymethyl cellulose, carrageenan, de-esterified pectin, gelatin, locust bean gum, methylcellulose, and starch.

Colour reaction: Dissolve as completely as possible 0,01 g of the sample by shaking with 0,15 ml of 0,1 N sodium hydroxide and add 1 ml of acid ferric sulfate solution. Within 5 minutes a cherry-red color develops that finally becomes deep purple.

pH: Between 2,0 and 3,5 (3 % suspension)

Loss on drying: Not more than 15 % (105 °C, 4 hours)

Sulfated ash: Not more than 8 % on the anhydrous basis

Sodium hydroxide (1 M solution) insoluble matter: Not more than 2 % on the anhydrous basis

Formaldehyde: Not more than 50 mg/kg

Arsenic: Not more than 3 mg/kg

Lead: Not more than 5 mg/kg

Mercury: Not more than 1 mg/kg

Cadmium: Not more than 1 mg/kg

Total plate count: Not more than 5 000 colonies per gram

Yeast and molds: Not more than 500 colonies per gram

Escherichia coli: Absent in 5 g

Salmonella spp.: Absent in 10 g