A:Infrared Absorption á197Kñ.

B:Ultraviolet Absorption á197Uñ—

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

Buffer solution— Add 4.0mLof n-butylamine to 1000mLof water.Adjust with phosphoric acid to a pHof 3.00±0.05.

Diluent— Prepare a mixture of water,acetonitrile,and methanol (3:1:1).

Mobile phase— Prepare a filtered and degassed mixture of Buffer solution,acetonitrile,and methanol (3:1:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard stock solution — Prepare a solution of USP Glipizide RSin methanol containing about 0.1mg per mL.

Standard solution— Prepare a solution of USP Glipizide Related Compound A RSin methanol containing about 0.1mg per mL.Pipet 2.0mLof this solution into a 100-mLvolumetric flask,add 2.0mLof the Standard stock solution,dilute with Diluent to volume,and mix.This solution contains about 2µg of USP Glipizide RSand about 2µg of USP Glipizide Related Compound A RSper mL.

Test solution— Transfer about 25mg of Glipizide,accurately weighed,to a 25-mLvolumetric flask,dissolve in and dilute with methanol to volume,and mix.Pipet 4.0mLof this solution into a 10-mLvolumetric flask,dilute with Diluentto volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The column temperature is maintained at 30.The flow rate is about 1mLper minute.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the retention time of the glipizide peak is about 45minutes;the relative retention times for glipizide related compound Aand glipizide are about 0.12and 1.0,respectively;the relative retention time of another known impurity,methyl-N-4-[2-(5-methylpyrazine-2-carboxamido)ethyl]benzenesulfonyl carbamate,is about 0.18;and the relative standard deviation for replicate injections is not more than 5.0%for each peak.

Procedure— Separately inject equal volumes (about 35µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak responses.Calculate the percentage of glipizide related compound Ain the portion of Glipizide taken by the formula: in which CAis the concentration,in µg per mL,of USP Glipizide Related Compound A RSin the Standard solution;Wis the amount of Glipizide,in mg,taken to prepare the Test solution;and rAand rSAare the peak responses for glipizide related compound Aobtained from the Test solutionand the Standard solution,respectively.Calculate the percentage of any other individual impurity in the portion of Glipizide taken by the formula: in which CGis the concentration,in µg per mL,of USP Glipizide RSin the Standard solution;riis the peak response for each individual impurity obtained from the Test solution;rSGis the glipizide peak response obtained from the Standard solution;and Wis defined above.Disregard any impurity peak that is less than 0.05%.Not more than 0.5%of any individual impurity is found;and not more than 1.5%of total impurities is found.

Buffer— Dissolve 13.8g of monobasic sodium phosphate in water,and dilute with water to 1000mL.Adjust with 2.0Nsodium hydroxide to a pHof 6.00±0.05.

Mobile phase— Prepare a filtered and degassed mixture of Bufferand methanol (55:45).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Glipizide RSin methanol,and dilute quantitatively with methanol to obtain a solution having a known concentration of about 0.1mg per mL.Transfer 25.0mLof this solution to a 50-mLvolumetric flask,dilute with Bufferto volume,and mix to obtain a solution having a known concentration of about 0.05mg per mL.

Assay preparation— Transfer about 20mg of glipizide,accurately weighed,to a 200-mLvolumetric flask,and dissolve in and dilute with methanol to volume.Pipet 25mLof this solution into a 50-mLvolumetric flask,dilute with Bufferto volume,and mix to obtain a solution having a known concentration of about 0.05mg per mL.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 225-nm detector and a 15-cm ×3.9-mm column that contains 5-µm packing L1.The flow rate is about 1.0mLper 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 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 glipizide (C21H27N5O4S)in the portion of Glipizide 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.