Identification,Infrared Absorption á197Mñ
Obtain the test specimen as follows.Place about 200mg in a suitable container,dissolve in about 20mLof water,add 2mLof 2Nsulfuric acid,and extract with 10mLof chloroform.Filter,and evaporate an aliquot of the chloroform layer.Dry the residue at 105

for 3hours.Use
USP Tolbutamide RSas the standard for comparison.
Assay
Mobile phase
and
Chromatographic systemPrepare as directed in the
Assayunder
Tolbutamide.
Internal standard solution
Prepare a solution of tolazamide in alcohol-free chloroform containing about 15mg per mL.
Diluting solution
Prepare an alcohol-free chloroform solution containing 3%(v/v)of glacial acetic acid.
Standard preparation
Dissolve an accurately weighed quantity of
USP Tolbutamide RSin
Internal standard solutionto obtain a known concentration of about 7.5mg per mL.Add
Diluting solutionto obtain a
Standard preparationhaving a final known concentration of about 1.5mg of tolbutamide per mL.
Assay preparation
Add about 15mLof water to 1container of Tolbutamide for Injection,and shake vigorously to dissolve the contents.Transfer the contents,using adequate rinsing with water,to a 50-mLvolumetric flask.Dilute with water to volume,and mix.Transfer an accurately measured portion of this solution,equivalent to about 75mg of tolbutamide,to a 50-mLvolumetric flask,add 10.0mLof Internal standard solution,and dilute with Diluting solutionto volume.Shake vigorously for about 15minutes,and centrifuge or allow to stand for about 15minutes.Use the lower,clear layer,as the Assay preparation.
Procedure
Separately inject equal volumes (about 20µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 0.6for tolbutamide and 1.0for tolazamide.Calculate the quantity,in mg,of C
12H
18N
2O
3Sin the portion of solution taken for the
Assay preparationby the formula:
50C(RU/RS),
in which
Cis the concentration,in mg per mL,of
USP Tolbutamide RSin the
Standard preparation,and
RUand
RSare the peak response ratios of the tolbutamide and internal standard peaks obtained from the
Assay preparationand the
Standard preparation,respectively.