Labeling
In addition to meeting the requirements for
Labelingunder
Injections á1ñ,fused-seal containers of the Injection in concentrations of 250mg per mLand greater are labeled to indicate that since pressure may develop on long storage,precautions should be taken to wrap the container in a protective covering while it is being opened.
Identification
A:
To a volume of Injection,equivalent to 40mg of ascorbic acid,add 4mLof 0.1Nhydrochloric acid,then add 4drops of methylene blue TS,and warm to 40

:the deep blue color becomes appreciably lighter or is completely discharged within 3minutes.
B:
The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparation,obtained as directed in the Assay.
C:
It responds to the flame test for Sodium á191ñ.
Assay
Mobile phase
Dissolve 15.6g of dibasic sodium phosphate and 12.2g of monobasic potassium phosphate in 2000mLof water,adjust with phosphoric acid to a pHof 2.5±0.05.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation
Dissolve an accurately weighed quantity of
USP Ascorbic Acid RSin
Mobile phase,and mix to obtain a solution having a known concentration of about 0.5mg per mL.
[NOTERefrigerate and store protected from light until use.The solution is stable for at least 24hours.Inject within 3hours after removal from the refrigerator.
]
Assay preparation
Dilute the Injection,quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a concentration of about 0.5mg per mL.[NOTERefrigerate and store protected from light until use.The solution is stable for at least 24hours.Inject within 3hours after removal from the refrigerator.]
Chromatographic system
(see
Chromatography á621ñ)The liquid chromatograph is equipped with a 245-nm detector and a 6-mm ×150-mm column that contains packing L39.The flow rate is about 0.6mLper minute.Chromatograph the
Standard preparation,and record the peak responses as directed for
Procedure:the column efficiency is not less than 3500theoretical plates,the tailing factor is not more than 1.6,and the relative standard deviation for replicate injections is not more than 1.5%.
Procedure
Separately inject equal volumes (about 4µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peak.Calculate the quantity,in mg,of ascorbic acid (C
6H
8O
6)in each mLof the Injection taken by the formula:
CD(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Ascorbic Acid RSin the
Standard preparation;Dis the dilution factor;and
rUand
rSare the peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.