Powdered Agar
Agar Pulveratum
Powdered Agar is the powder of Agar.
Description:
Powdered Agar appears as a white powder, is odorless, and is tasteless and mucilagenous.
Under a microscope, Powdered Agar, immersed in olive oil or liquid paraffin, reveals angular granules with striations or nearly spheroidal granules 5 to 60 mm in diameter.
It becomes transparent in chloral hydrate TS.
It is practically insoluble in organic solvents.
A boiling solution of Powdered Agar (1 in 100) is neutral.
Identification:
(1) To a part of Powdered Agar add drop wise iodine TS: a dark blue to reddish purple color develops.
(2) Dissolve 1 g of Powdered Agar in 65 mL of water by boiling for 10 minutes with constant stirring, and add a sufficient amount of hot water to maintain the original volume lost by evaporation: the solution is clear. Cool the solution between 300C and 390C: the solution forms a firm, resilient gel, which does not melt below 850C.
Purity:
(1) Sulfuric acid.Dissolve 1.0 g of Powdered Agar in 100 mL of water by boiling: the solution is not acid.
(2) Sulfurous acid and starch.To 5 mL of the solution obtained in (1) add 2 drops of iodine TS: the solution is not decolorized immediately, and does not show a blue color.
(3) Insoluble matter.To 7.5 g of Powdered Agar add 500 mL of water, boil for 15 minutes, and add water to make exactly 500 mL. Take exactly 100 mL of the solution, add 100 mL of hot water, heat to boiling, filter while hot through a tared glass filter (G3), wash the residue with a small amount of hot water, and dry the residue at 1050C for 3 hours: the mass of the residue is not more than 15.0 mg.
(4) Water absorption.To 5.0 g of Powdered Agar add water to make 100 mL, shake well, allow to stand at 250C for 24 hours, and filter through moistened glass wool in a 100 mL graduated cylinder: the volume of the filtrate is not more than 75 mL.
Loss on drying:
Not more than 22.0z (6 hours).
Total ash:
Not more than 4.5z.
Acid-insoluble ash:
<5.01> Not more than 0.5z.
Containers and storage:
Containers.Tight containers.
