A: Transfer a volume of Injection,equivalent to about 3mg of scopolamine hydrobromide,to a 50-mLseparator,dilute with water,if necessary,to 10mL,add 0.2mLof ammonium hydroxide,and extract with 25mLof chloroform.Add 50mLof ether to the chloroform solution,and pass the mixture through a 25-×250-mm chromatographic tube fitted with a pledget of glass wool at the base and packed with 2g of purified siliceous earth that previously has been mixed with 1mLof 0.2Nphosphoric acid saturated with sodium bromide.Discard the eluate,and pass 25mLof water-saturated ether through the column and discard.Elute with 100mLof water-saturated chloroform,collect the eluate in a suitable receiver,and evaporate just to dryness.Dissolve the residue in 1mLof alcohol,and proceed as directed inIdentification testAunderScopolamine Hydrobromide,beginning with “and evaporate the solution on a steam bath to dryness.”

B: Add to the Injection silver nitrate TS:a yellowish white precipitate,insoluble in nitric acid but slightly soluble in 6Nammonium hydroxide,is formed.

pH9.0Buffer— Dissolve 34.8g of dibasic potassium phosphate in 900mLof water,and adjust with 3Nhydrochloric acid or 1Nsodium hydroxide,as necessary,to a pHof 9.0,determined electrometrically,and mix.

Internal standard solution— Transfer about 25mg of homatropine hydrobromide to a 50-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.Prepare fresh daily.

Standard stock solution— Transfer about 10mg of USP Scopolamine Hydrobromide RS,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.Prepare fresh daily.

Standard preparation— Pipet 10mLof theStandard stock solutioninto a separator,add 2.0mLofInternal standard solutionand 5.0mLofpH9.0Buffer,and carefully adjust the solution with 1Nsodium hydroxide to a pHof 9.0,avoiding any excess.Immediately extract with two 10-mLportions of methylene chloride,filter the methylene chloride extracts through 1g of anhydrous sodium sulfate supported by a small cotton plug in a funnel into a 50-mLbeaker,and evaporate under nitrogen to approximately 2.0mL.

Assay solution— Transfer an accurately measured volume of Injection,equivalent to about 10mg of scopolamine hydrobromide,to a 100-mLvolumetric flask.Dilute with water to volume,and mix.

Assay preparation— Pipet 10mLof theAssay solution into a separator,and proceed as directed forStandard preparation,beginning with “add 2.0mLofInternal standard solution.”

Chromatographic system(see Chromatography á621ñ)— The gas chromatograph contains a 2-mm ×1.8-m glass column packed with 3%liquid phase G3on support S1AB.The carrier gas is nitrogen,flowing at a rate of 25mLper minute.The column temperature is maintained at 225.Chromatograph theStandard preparation,and record the peak responses as directed forProcedure:the resolution factor,R,between homatropine and scopolamine is not less than 5;the tailing factor is not more than 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 1µL)of theStandard preparation and theAssay preparationinto the chromatograph,record the chromatograms,and measure the peak areas.Calculate the ratio,AU,of the area of the scopolamine hydrobromide peak to the area of the internal standard peak in the chromatogram from theAssay preparation,and similarly calculate the ratio,AS,in the chromatogram from theStandard preparation.Calculate the quantity,in mg,of scopolamine hydrobromide (C17H21NO4·HBr·3H2O)in the volume of Injection taken by the formula: in which 1.141is the ratio of the molecular weight of scopolamine hydrobromide trihydrate to that of anhydrous scopolamine hydrobromide;Wis the weight,in mg,of USP Scopolamine Hydrobromide RSin theStandard preparation;andAUandASare as calculated above.