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.
Identification—
A:
To 5mLof a 1in 150solution in 0.1Nsodium hydroxide add 1mLof calcium chloride TS:a voluminous,gelatinous precipitate is formed.
B:
To 5mLof a 1in 150solution in 0.1Nsodium hydroxide add 1mLof 4Nsulfuric acid:a heavy,gelatinous precipitate is formed.
C:
To about 5mg in a test tube add 5mLof water,1mLof a freshly prepared 1in 100solution of 1,3-naphthalenediol in alcohol,and 5mLof hydrochloric acid.Heat the mixture to boiling,boil gently for 3minutes,then cool to about 15
.Transfer the contents of the test tube to a 30-mLseparator with the aid of 5mLof water,and extract with 15mLof isopropyl ether:the isopropyl ether extract exhibits a deeper purplish hue than that from a blank,similarly prepared.
.Transfer the contents of the test tube to a 30-mLseparator with the aid of 5mLof water,and extract with 15mLof isopropyl ether:the isopropyl ether extract exhibits a deeper purplish hue than that from a blank,similarly prepared.
Microbial limits á61ñ—
The total bacterial count does not exceed 200per g,and the tests for Salmonellaspecies and Escherichia coliare negative.
pHá791ñ:
between 1.5and 3.5,in a 3in 100dispersion in water.
Loss on drying á731ñ—
Dry it at 105for 4hours:it loses not more than 15.0%of its weight.
for 4hours:it loses not more than 15.0%of its weight.
Total ash á561ñ—
Proceed as directed for Total Ash underArticles of Botanical Origin—Methods of Analysis á561ñ,carefully igniting about 4g of Alginic Acid,accurately weighed,in a tared platinum dish,until the residue is thoroughly carbonized (about 5minutes),and then igniting in a muffle furnace at a temperature of 800±25until the carbon is completely burned off (20to 35minutes):not more than 4.0%of ash is found.
until the carbon is completely burned off (20to 35minutes):not more than 4.0%of ash is found.
Arsenic,Method IIá211ñ:
3ppm.
Lead—
Add 1.0g to 20mLof nitric acid in a 250-mLconical flask,mix,and heat carefully until the Alginic Acid is dissolved.Continue heating until the volume is reduced to about 7mL.Cool rapidly to room temperature,transfer to a 100-mLvolumetric flask,and dilute with water to volume.A50.0-mLportion of this solution contains not more than 5µg of lead (corresponding to not more than 0.001%)when tested according to the test for Lead á251ñ,15mLof ammonium citrate solution,3mLof potassium cyanide solution,and 500µLof hydroxylamine hydrochloride solution being used.After the first dithizone extraction,wash the combined chloroform layers with 5mLof water,discarding the water layer and continuing in the usual manner by extracting with 20mLof 0.2Nnitric acid.
Heavy metals,Method IIá231ñ:
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 á401ñ—
Suspend about 1g of Alginic Acid,accurately weighed,in a mixture of 50mLof water and 30.0mLof calcium acetate solution (11in 250).Shake thoroughly,allow the mixture to stand for 1hour,add phenolphthalein TS,and then titrate the liberated acetic acid with 0.1Nsodium hydroxide VS.Perform a blank determination,and calculate the acid value taken by the formula:
5.611(A-B)/W,
in which 5.611is one-tenth the molecular weight of potassium hydroxide;Aand Bare the volumes,in mL,of 0.100Nsodium hydroxide consumed in the titrations of the test preparation and blank,respectively;and Wis the weight,in g,of Alginic Acid taken.The acid value of Alginic Acid,calculated on the dried basis,is not less than 230.
Auxiliary Information—
Staff Liaison:Daniel K.Bempong,Ph.D.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2953
Phone Number:1-301-816-8143