A: Place a portion of Oral Solution,equivalent to 50mg of diphenhydramine hydrochloride,in a separator,add 0.5mLof 2Nsulfuric acid,and extract with three 15-mLportions of ether,discarding the extracts.Add 5mLof water.In a second separator dissolve 50mg of USP Diphenhydramine Hydrochloride RSin 25mLof water.Treat each solution as follows.Add 2mLof 1Nsodium hydroxide,and extract with 75mLof n-heptane.Wash the n-heptane extract with 10mLof water,evaporate the extract to dryness,and dissolve the residue in 4mLof carbon disulfide.Pass through a dry filter to clarify the solution,if necessary,and proceed as directed under Identification—Organic Nitrogenous Bases á181ñ,beginning with “Determine the absorption spectra of the filtered solutions”:the Oral Solution meets the requirements of the test.

B: 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.

Mobile phase,Standard preparation,System suitability solution,andChromatographic system— Prepare as directed in the Assayunder Diphenhydramine Hydrochloride.

Assay preparation— Transfer an accurately measured volume of Oral Solution,equivalent to about 50mg of diphenhydramine hydrochloride,to a 100-mLvolumetric flask,dilute with water to volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Diphenhydramine Hydrochloride.Calculate the quantity,in mg,of diphenhydramine hydrochloride (C17H21NO·HCl)in each mLof the Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Diphenhydramine Hydrochloride RSin the Standard preparation;Vis the volume,in mL,of Oral Solution taken;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.