Ascorbic Acid Oral Solution
» Ascorbic Acid Oral Solution is a solution of Ascorbic Acid in a hydroxylic organic solvent or an aqueous mixture thereof. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C6H8O6.
Packaging and storage— Preserve in tight, light-resistant containers.
Labeling— Label Oral Solution that contains alcohol to state the alcohol content.
A: To a volume of Oral Solution equivalent to 40 mg of ascorbic acid add 4 mL of 0.1 N hydrochloric acid, then add 4 drops of methylene blue TS, and warm to 40: the deep blue color becomes appreciably lighter or is completely discharged within 3 minutes.
B: To a volume of Oral Solution equivalent to 20 mg of ascorbic acid add 15 mL of trichloroacetic acid solution (1 in 20), then add about 200 mg of activated charcoal, shake the mixture vigorously for 1 minute, and filter through a small fluted filter, returning the filtrate, if necessary, until clear. To 5 mL of the filtrate add 1 drop of pyrrole, agitate gently until dissolved, then heat in a bath at 50: a blue color develops.
Alcohol content (if present), Method I 611: between 90.0% and 110.0% of the labeled amount of C2H5OH.
Assay— Transfer to a 100-mL volumetric flask an accurately measured volume of Oral Solution, equivalent to about 50 mg of ascorbic acid, previously diluted with water if necessary. Add 20 mL of metaphosphoric-acetic acids TS, dilute with water to volume, and mix. Accurately measure a volume of the dilution, equivalent to about 2 mg of ascorbic acid, into a 50-mL conical flask, add 5 mL of metaphosphoric-acetic acids TS, and titrate with standard dichlorophenol-indophenol solution until a rose-pink color persists for at least 5 seconds. Correct for the volume of the dichlorophenol-indophenol solution consumed by a mixture of 5.5 mL of metaphosphoric-acetic acids TS and 15 mL of water.
From the ascorbic acid equivalent of the standard dichlorophenol-indophenol solution, calculate the ascorbic acid content in each mL of the Oral Solution.
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Monograph Curtis Phinney

(DSN05) Dietary Supplements - Non-Botanicals
USP32–NF27 Page 1581