A: Transfer a portion of the Cefprozil for Oral Suspension powder,equivalent to about 50mg of cefprozil,to a 20-mLglass-stoppered test tube,add 10mLof a mixture of acetone and 0.1Nhydrochloric acid (4:1),shake for 5minutes,and allow to settle.Use the supernatant as the test solution.Dissolve a suitable quantity of USP Cefprozil (Z)-Isomer RSin a mixture of acetone and 0.1Nhydrochloric acid (4:1)to obtain a Standard solution containing 5mg per mL.Apply separate 10-µLportions of the test solution and the Standard solution to a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Allow the spots to dry,and develop the chromatogram in an equilibrated chromatographic chamber with a solvent system consisting of a mixture of butyl alcohol,water,and glacial acetic acid (60:20:20)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the chamber,and allow the plate to air-dry in a hood.Place the dry plate in a chamber containing iodine vapors.Examine the plate,and locate the spots:the RFvalue of the principal spot in the chromatogram obtained from the Test solutioncorresponds to that obtained from the Standard solution.

B: The retention times of the cefprozil(Z)-isomer and cefprozil(E)-isomer peaks in the chromatogram of the Assay preparationcorrespond to those of the Standard preparations,as obtained in the Assay.

FOR SOLIDS PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

Add the following:

FOR POWDER PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.USP28

Mobile phase,Standard cefprozil (Z)-isomer preparation,Standard cefprozil (E)-isomer preparation,Resolution solution,and Chromatographic system— Proceed as directed in the Assayunder Cefprozil.

Assay preparation— Constitute 1container of Cefprozil for Oral Suspension as directed in the labeling.Transfer an accurately measured volume of the Cefprozil for Oral Suspension,freshly mixed and free from air bubbles,equivalent to about 250mg of cefprozil,to a 250-mLvolumetric flask,dilute with water to volume,and mix,sonicating briefly.Transfer 15.0mLof this solution to a 50-mLvolumetric flask,dilute with water to volume,and mix.Pass a portion of this solution through a filter having a 0.5-µm or finer porosity,and use the filtrate as the Assay preparation.[NOTE—Use this solution within 6hours.]

Procedure— Proceed as directed for Procedurein the Assayunder Cefprozil.Calculate the quantity,in mg,of cefprozil(Z)-isomer and cefprozil (E)-isomer in each mLof the Cefprozil for Oral Suspension taken by the formula: in which Vis the volume,in mL,of Cefprozil for Oral Suspension taken,and the other terms are as defined therein.Calculate the quantity,in mg,of cefprozil (C18H19N3O5S)in each mLof Cefprozil for Oral Suspension taken by adding the values,in mg per mL,obtained from the cefprozil(Z)-isomer and from the cefprozil (E)-isomer.