A: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparation,as obtained in the Assay.

B: Transfer a quantity of finely powdered Tablets,equivalent to about 10mg of glipizide,to a glass-stoppered centrifuge tube,add 10mLof methanol,insert a stopper into the tube,and shake.Centrifuge the mixture,and use the clear supernatant as the test solution.Separately apply,as streaks about 7cm in length,100µLof the test solution and 100µLof a Standard solution of USP Glipizide RSin methanol containing 1mg per mL,to a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Allow the streaks to dry,and develop the chromatogram in a solvent system consisting of a mixture of toluene,ethyl acetate,and 98%formic acid (5:3:2)until the solvent front has moved to within 2.5cm of the top of the plate.Remove the plate from the developing chamber,mark the solvent front,and dry the plate at 80for 30minutes.Cool the plate,spray it with 0.5%sodium hypochlorite solution,and allow the plate to air-dry.Spray the plate with alcohol,air-dry,and spray with a freshly prepared mixture of 1%soluble starch solution and 1%potassium iodide solution (1:1):the RFvalue of the principal band obtained from the test solution corresponds to that obtained from the Standard solution.

Medium: simulated intestinal fluid TS(without pancreatin);900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Tolerances— Not less than 80%(Q)of the label claim of C21H27N5O4Sis dissolved in 45minutes.

Buffer ,Mobile phase,and Standard preparation—Prepare as directed in the Assayfor Glipizide.

Test preparation— Transfer 1Tablet to an appropriate volumetric flask,add a volume of Bufferequal to one-half of the total flask volume,and shake by mechanical means for 10minutes to allow the Tablet to disintegrate completely.Dilute with methanol to volume,and sonicate for 15minutes to obtain a solution having a concentration of about 0.05mg of glipizide per mL.Filter through a solvent-resistant filter.

Chromatographic system (see Chromatography á621ñ)—Proceed as directed in the Assayfor Glipizide.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure:the relative standard deviation for replicate injections is not more than 1.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Test preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C21H27N5O4Sin the Tablet taken by the formula: in which Cis the concentration,in mg per mL,of USP Glipizide RSin the Standard preparation;Vis the volume,in mL,of the Test preparationtaken;and rUand rSare the peak responses obtained from the Test preparationand the Standard preparation,respectively.

Buffer and Mobile phase—Prepare as directed in the Assayfor Glipizide.

Standard stock solution— Dissolve an accurately weighed quantity of USP Glipizide Related Compound A RSin methanol to obtain a solution having a known concentration of about 50µg per mL.

Standard solution— Dissolve an accurately weighed quantity of USP Glipizide RSin methanol.To this solution add sufficient Standard stock solution,and dilute quantitatively with methanol to obtain a solution having known concentrations of about 100µg per mLof USP Glipizide RSand about 0.5µg per mLof USP Glipizide Related Compound A RS.Transfer 25mLof this solution to a 50-mLvolumetric flask,dilute with Bufferto volume,and mix.

Test solution— Use the Assay preparation.

Chromatographic system— Prepare as directed in the Assayfor Glipizide.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.2for glipizide related compound Aand 1.0for glipizide;the resolution,R,between glipizide related compound Aand glipizide is not less than 1.5;and the relative standard deviation for replicate injections is not more than 5%for glipizide related compound A.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of N-{2-[(4-aminosulfonyl)phenyl]ethyl}-5-methyl-pyrazinecarboxamide (glipizide related compound A)in the Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Glipizide Related Compound A RSin the Standard solution;and rUand rSare the peak responses of glipizide related compound Aobtained from the Test solutionand the Standard solution,respectively:not more than 2.0%of glipizide related compound Arelative to the glipizide content,as determined in the Assay,is found.

Buffer ,Mobile phase,and Standard preparation—Prepare as directed in the Assayfor Glipizide.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 5mg of glipizide,to a 100-mLvolumetric flask.Add 50mLof methanol,and place in an ultrasonic bath for 15minutes.Dilute with Bufferto volume,and place in the ultrasonic bath for an additional 15minutes.Filter through a solvent-resistant filter.

Chromatographic system (see Chromatography á621ñ)—Prepare as directed in the Assayfor Glipizide.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 1.0%.

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.Calculate the quantity,in mg,of C21H27N5O4Sin the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Glipizide RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.