Identification—
Triturate a quantity of finely powdered Tablets with sufficient diluted alcohol to make approximately the equivalent of a 1 in 50 solution of ascorbic acid, filter, and proceed with the following tests:
B:
To 2 mL of the filtrate 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.
C:
To 1 mL of the filtrate add 15 mL of a solution of trichloroacetic acid (1 in 20), 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, and agitate gently until dissolved, then heat in a bath at 50
: a blue color develops.
Dissolution, Procedure for a Pooled Sample 
711
—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C
6H
8O
6 dissolved, employing the procedure set forth in the
Assay and conducting the procedure without delay, making any necessary modifications.
Tolerances—
Not less than 75% (Q) of the labeled amount of C6H8O6 is dissolved in 45 minutes.
Assay—
Transfer not less than 20 Tablets to a 1000-mL volumetric flask containing 250 mL of metaphosphoric-acetic acids TS. Insert the stopper in the flask, and shake by mechanical means for 30 minutes or until the tablets have disintegrated completely. Dilute with water to volume, and mix. Transfer a portion of the solution to a centrifuge tube, and centrifuge until a clear supernatant is obtained. Quantitatively dilute the clear supernatant with water, if necessary, to obtain a solution containing about 500 µg of ascorbic acid per mL. Pipet 4 mL of the solution, equivalent to about 2 mg of ascorbic acid, into a 50-mL conical flask, and proceed as directed in the
Assay under
Ascorbic Acid Oral Solution, beginning with “Add 5 mL of metaphosphoric-acetic acids TS.”
From the ascorbic acid equivalent of the standard dichlorophenol-indophenol solution, calculate the content of ascorbic acid in each Tablet.
