Weight variation á2091ñ:
meet the requirements.
NOTEIn the following Assays,where more than one Assaymethod is given for an individual ingredient,the requirements may be met by following any one of the specified methods,the method used being stated in the labeling only if Method 1is not used.
Assay for folic acid,Method 2
[NOTEUse low-actinic glassware throughout this procedure.
]
Diluting solution
Prepare a solution of ammonium hydroxide containing 60µg per mL.
Mobile phase
Transfer 0.4mLof triethylamine,15.0mLof glacial acetic acid,and 350mLof methanol to a 2000-mLvolumetric flask,dilute with 0.008Msodium 1-hexanesulfonate to volume,and mix.Filter,and degas.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard stock solution
Dissolve an accurately weighed quantity of
USP Folic Acid RSin
Diluting solutionto obtain a solution having a known concentration of about 60µg per mL.Prepare this solution fresh daily.
Standard preparation
Transfer 5.0mLof
Standard stock solutionto a stoppered 125-mLflask.Add 10.0mLof a mixture of methanol and glacial acetic acid (9:1)and 30.0mLof a mixture of methanol and ethylene glycol (1:1).Insert the stopper,shake for 15minutes in a water bath maintained at 60

,and cool.Filter,discarding the first few mLof the filtrate.
Assay preparation
Weigh and finely powder a counted number of Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 0.3mg of folic acid,to a stoppered 125-mLflask.Proceed as directed for Standard preparationbeginning with Add 10.0mL.
Chromatographic system (see Chromatography á621ñ)
The liquid chromatograph is equipped with a 270-nm detector and a 4.6-mm ×25-cm column that contains packing L7.The column temperature is maintained at 50

,and the flow rate is about 2.0mLper minute.Chromatograph the
Standard preparation,and record the peak responses as directed for
Procedure:the relative standard deviation for replicate injections is not more than 2.0%.
Procedure
Separately inject equal volumes (about 5µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the areas of the major peaks.Calculate the quantity,in mg,of folic acid (C
19H
19N
7O
6)in the portion of Tablets taken by the formula:
40C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Folic Acid RSin the
Standard preparation;and
rUand rSare the peak responses of folic acid obtained from the
Assay preparationand the
Standard preparation,respectively.