A: Thin-Layer Chromatographic Identification Test á201ñ—

B: The retention times of the major peaks in the chromatogram of the Assay preparationcorrespond to those in the chromatogram of the Standard preparation,as obtained in the Assay.

Diluent— Prepare a mixture of methanol and water (80:20).

Mobile phase— Prepare a filtered and degassed mixture of methanol,water,0.1Nammonium hydroxide solution,and 0.1Nammonium nitrate solution (27:3:2:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve accurately weighed quantities of USP Bromodiphenhydramine Hydrochloride RSand USP Codeine Phosphate RSin Diluent,and dilute quantitatively,and stepwise if necessary,with Diluentto obtain a solution having known concentrations of about 100µg per mLand 80µg per mL,respectively.

Assay preparation— Using a pipet calibrated “to contain”,transfer an accurately measured volume of Oral Solution,equivalent to about 10mg of bromodiphenhydramine hydrochloride and 8mg of codeine phosphate,to a 100-mLvolumetric flask,dissolve in and dilute with Diluentto volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30.0-cm column that contains packing L3.The flow rate is about 1.0mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 1.0for bromodiphenhydramine and 1.4for codeine;the resolution,R,between bromodiphenhydramine and codeine is not less than 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the peak responses for bromodiphenhydramine and codeine.Calculate the quantity,in mg,of bromodiphenhydramine hydrochloride (C17H20BrNO·HCl)in each mLof the Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Bromodiphenhydramine Hydrochloride RSin the Standard preparation;Vis the volume,in mL,of Oral Solution taken to prepare the Assay preparation;and rUand rSare the bromodiphenhydramine peak responses obtained from the Assay preparationand the Standard preparation,respectively.Calculate the quantity,in mg,of codeine phosphate hemihydrate (C18H21NO3·H3PO4·½H2O)in each mLof the Oral Solution taken by the formula: in which 406.37and 397.36are the molecular weights of codeine phosphate hemihydrate and anhydrous codeine phosphate,respectively;Cis the concentration,in mg per mL,of USP Codeine Phosphate RSin the Standard preparation;Vis the volume,in mL,of Oral Solution taken to prepare the Assay preparation;and rUand rSare the codeine peak responses obtained from the Assay preparationand the Standard preparation,respectively.