A: Infrared Absorption á197Mñ.

B: The chromatogram of the Assay preparationobtained as directed in the Assayexhibits a major peak for glyburide,the retention time of which corresponds to that exhibited in the chromatogram of the Standard preparation,both relative to the internal standard,as obtained in the Assay.

Mobile phase— Prepare as directed in the Assay.

Test solution— To about 10mg of Glyburide,accurately weighed,add 10mLof acetonitrile,and shake to dissolve.Add 4mLof water,and mix.

Chromatographic system— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L7.The flow rate is about 2mLper minute.Chromatograph the Test solution,and record the peak responses as directed for Procedure:the column efficiency is not less than 3500theoretical plates.

Procedure— Inject a volume (about 20µL)of the Test solutioninto the chromatograph,record the chromatogram,and measure the areas for the major peaks.Calculate the percentage of each impurity in the portion of Glyburide taken by the formula: in which riis the peak response for each impurity;and rsis the sum of the responses of all of the peaks:not more than 1.5%of any impurity,which elutes before glyburide,is found;not more than 0.5%of any other individual impurity is found;and not more than 2.0%of total impurities is found.

Mobile phase— Dissolve 2.6g of monobasic ammonium phosphate in 450mLof water.Add 550mLof acetonitrile,filter,and degas.Adjust,if necessary,with phosphoric acid or sodium hydroxide to a pHof 5.25±0.30.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Internal standard solution— Dissolve progesterone in acetonitrile to obtain a solution containing about 0.2mg per mL.

Standard preparation— To about 10mg of USP Glyburide RS,accurately weighed,add 20.0mLof Internal standard solution,and shake vigorously to dissolve.Add 4.0mLof water,and mix.

Assay preparation— To about 10mg of Glyburide,accurately weighed,add 20.0mLof Internal standard solution,and shake vigorously to dissolve.Add 4.0mLof water,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L7.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 0.4for glyburide and 1.0for progesterone;the resolution,R,between glyburide and progesterone is not less than 5.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the heights for the major peaks.Calculate the quantity,in mg,of C23H28ClN3O5Sin the portion of Glyburide taken by the formula: in which WSis the weight,in mg,of USP Glyburide RStaken to prepare the Standard preparation;and RUand RSare the peak height ratios obtained from the Assay preparationand the Standard preparation,respectively.