A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

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

test 1 (limit of methyl-N-4-[2-(5-methylpyrazine-2-carboxamido)ethyl] benzenesulfonyl carbamate)—

test 2 (limit of related compounds A, B, and C)—

0.02 M Phosphate buffer— Dissolve 2.84 g of anhydrous dibasic sodium phosphate in 1000 mL of water. Adjust with phosphoric acid to a pH of 6.00 ± 0.05.

Mobile phase— Prepare a filtered and degassed mixture of 0.02 M Phosphate buffer, acetonitrile, and methanol (70:20:10). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard stock preparation— Transfer accurately weighed amounts of USP Glipizide RS to a suitable volumetric flask, and dissolve in methanol with the aid of sonication for about 5 minutes to obtain a solution having a known concentration of about 1.0 mg of glipizide per mL.

Standard preparation— Accurately transfer 10.0 mL of the Standard stock preparation into a 100-mL volumetric flask containing 20 mL of acetonitrile and 60 mL of 0.02 M Phosphate buffer. Sonicate the solution for about 5 minutes, dilute with 0.02 M Phosphate buffer to volume, and mix. This solution contains about 0.1 mg of glipizide per mL.

Impurity standard stock solution— Transfer accurately weighed amounts of USP Glipizide Related Compound A RS, USP Glipizide Related Compound B RS, and USP Glipizide Related Compound C RS to a suitable volumetric flask, and dissolve in methanol with the aid of sonication for about 5 minutes to obtain a solution having known concentrations of about 0.1 mg of each of glipizide related compounds A, B, and C per mL. [note—Glipizide related compound A is N-{2-[(4-aminosulfonyl)phenyl]ethyl}-5-methyl-pyrazinecarboxamide; glipizide related compound B is 6-methyl-N-[2-(4-sulfamoylphenyl)ethyl]pyrazine-2-carboxamide; and glipizide related compound C is 1-cyclohexyl-3-[[4-[2-[[(6-methylpyrazin-2-yl)carbonyl]amino]ethyl]phenyl]sulfonyl]urea.]

System suitability stock solution— Transfer an accurately weighed amount of USP Glipizide RS to a suitable volumetric flask, dissolve in methanol with the aid of sonication for about 5 minutes, and add an accurately measured volume of Impurity standard stock solution to obtain a solution containing about 1.0 mg of glipizide and about 0.005 mg of each of glipizide related compounds A, B, and C per mL.

System suitability solution— Accurately transfer 10.0 mL of the System suitability stock solution into a 100-mL volumetric flask containing 20 mL of acetonitrile and 60 mL of 0.02 M Phosphate buffer. Sonicate the solution for about 5 minutes, dilute with 0.02 M Phosphate buffer to volume, and mix.

Sensitivity solution— Accurately transfer 5.0 mL of the System suitability solution into a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Assay stock preparation— Transfer about 100 mg of Glipizide, accurately weighed, to a 100-mL volumetric flask, dissolve in about 50 mL of methanol with the aid of sonication for about 5 minutes, dilute with methanol to volume, and mix.

Assay preparation— Accurately transfer 10.0 mL of the Assay stock preparation into a 100-mL volumetric flask containing 20 mL of acetonitrile and 60 mL of 0.02 M Phosphate buffer. Sonicate the solution for about 5 minutes, dilute with 0.02 M Phosphate buffer to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 225-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L43. The column temperature is maintained at 40. The flow rate is about 1 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the elution order is glipizide related compound A, glipizide related compound B, glipizide, and glipizide related compound C; the resolution, R, between glipizide related compound A and glipizide related compound B peaks is not less than 1.8, and the resolution, R, between glipizide and glipizide related compound C peaks is also not less than 1.8; the tailing factor for the glipizide peak is not more than 2.0; and the relative standard deviation for 5 replicate injections is not more than 1.5% for the glipizide peak and not more than 5.0% for each of the related compounds peaks. Chromatograph the Sensitivity solution, and record the peak responses as directed for Procedure: the signal-to-noise ratio for each of glipizide related compound A and glipizide related compound B peaks is not less than 15.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of C21H27N5O4S in the portion of Glipizide taken by the formula: in which CS and CU are the concentrations, in mg per mL, of glipizide in the Standard preparation and the Assay preparation, respectively; and rU and rS are the glipizide peak responses obtained from the Assay preparation and the Standard preparation, respectively.