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Alginic Acid is a hydrophilic colloidal carbohydrate extracted with dilute alkali from various species of brown seaweeds (Phaeophyceae).
Analysis: To 5 mL of a 1-in-150 solution in 0.1 N sodium hydroxide add 1 mL of calcium chloride TS.
Acceptance criteria: A voluminous, gelatinous precipitate is formed.
Analysis: To 5 mL of a 1-in-150 solution in 0.1 N sodium hydroxide add 1 mL of 4 N sulfuric acid.
Acceptance criteria: A heavy, gelatinous precipitate is formed.
Analysis: To 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 min, then cool to 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.
Acceptance criteria: The isopropyl ether extract exhibits a deeper purplish hue than that from a blank, similarly prepared.
• Arsenic, Method II 211: NMT 3 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 Alginic Acid 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 50.0 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: NMT 5 µg of lead (corresponding to NMT 10 ppm)
• Heavy Metals, Method II 231
Analysis: Use a platinum crucible for the ignition, 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 aerobic microbial count does not exceed 2 × 102 cfu/g, and the tests for Salmonella species and Escherichia coli are negative.
• pH 791: 1.53.5, in a 3-in-100 dispersion in water
• Loss on Drying 731: Dry a sample at 105 for 4 h: it loses NMT 15.0% of its weight.
• Articles of Botanical Origin, Total Ash 561
Sample: 4 g of Alginic Acid
Analysis: Proceed as directed in the chapter, carefully igniting the Sample in a tared platinum dish, until the residue is thoroughly carbonized (5 min). Then ignite in a muffle furnace at a temperature of 800 ± 25 until the carbon is completely burned off (2035 min).
Acceptance criteria: NMT 4.0% of ash
• Fats and Fixed Oils, Acid Value 401
Sample: 1 g of Alginic Acid
Analysis: Suspend the Sample 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 h, and add phenolphthalein TS. Titrate the liberated acetic acid with 0.1 N sodium hydroxide VS. Perform a blank determination, and calculate the Acid Value:
Result = [(VS VB) × N × F]/W
Acceptance criteria: NLT 230 on the dried basis
• Packaging and Storage: Preserve in well-closed containers.
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USP35NF30 Page 1690