Identification—
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.
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.
611
:
between 90.0% and 110.0% of the labeled amount of C2H5OH.