Ascorbic Acid Oral Solution
DEFINITION
Ascorbic Acid Oral Solution is a solution of Ascorbic Acid in a hydroxylic organic solvent or an aqueous mixture thereof. It contains NLT 90.0% and NMT 110.0% of the labeled amount of ascorbic acid (C6H8O6).
IDENTIFICATION
•  A.
Sample solution:  A volume of Oral Solution equivalent to 40 mg of ascorbic acid
Analysis:  To the Sample solution add 4 mL of 0.1 N hydrochloric acid, then 4 drops of methylene blue TS, and warm to 40.
Acceptance criteria:  The deep blue color becomes appreciably lighter or is completely discharged within 3 min.
•  B.
Sample solution:  A volume of Oral Solution equivalent to 20 mg of ascorbic acid
Analysis:  To the Sample solution add 15 mL of trichloroacetic acid solution (1 in 20). Add 200 mg of activated charcoal, shake the mixture vigorously for 1 min, and pass 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.
Acceptance criteria:  A blue color develops.
ASSAY
•  Procedure
Sample solution:  Transfer a volume of Oral Solution equivalent to 50 mg of ascorbic acid, previously diluted with water if necessary, to a 100-mL volumetric flask. Add 20 mL of metaphosphoric–acetic acid TS, dilute with water to volume, and mix.
Blank:  A mixture of 5.5 mL of metaphosphoric–acetic acid TS and 15 mL of water
Titrimetric system 
Mode:  Direct titration
Titrant:  Standard dichlorophenol–indophenol VS
Analysis:  Transfer a volume of the Sample solution, equivalent to 2 mg of ascorbic acid, into a 50-mL conical flask. Add 5 mL of metaphosphoric–acetic acid TS, and titrate with Titrant until a rose-pink color persists for at least 5 s. Correct for the volume of the Titrant consumed by the Blank.
Calculate the percentage of ascorbic acid (C6H8O6) in the portion of Oral Solution taken:
Result = {[(VS VB) × F]/W} × 100
VS== Titrant volume consumed by the Sample solution (mL)
VB== Titrant volume consumed by the Blank (mL)
F== concentration of Titrant in terms of its equivalent of ascorbic acid (mg/mL)
W== nominal amount of ascorbic acid taken for Analysis (mg)
Acceptance criteria:  90.0%–110.0%
OTHER COMPONENTS
•  Alcohol Determination, Method I 611 (if present): 90.0%–110.0% of the labeled content of alcohol (C2H5OH)
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight, light-resistant containers.
•  Labeling: Label Oral Solution that contains alcohol to state the alcohol content.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Natalia Davydova
Scientific Liaison
1-301-816-8328
(DS2010) Monographs - Dietary Supplements
USP35–NF30 Page 2243