Identification—
Infrared Absorption á197Kñ—
Test specimen—
Transfer the final solution obtained from the titration in the Assayto a separator,add about 1mLof 0.1Nsulfuric acid,and shake with 25mLof ether.(Methyl red enters the ether phase.)Drain the aqueous layer into another separator,add 5mLof 1Nsodium hydroxide,and shake with 10mLof chloroform.Drain the chloroform layer into a small flask containing 2g of anhydrous sodium sulfate,and swirl.Pour the chloroform solution through a small cotton pledget,pre-rinsed with chloroform,into a beaker,and evaporate to about 5mL.Apply a few drops of the solution directly to a potassium bromide plate,and completely remove the chloroform by warming for 2to 3minutes under an IRlamp.
Assay—
Evaporate an accurately measured volume of Elixir,equivalent to about 250mg of bromodiphenhydramine hydrochloride,to about half the original volume,using a suitable vacuum evaporator.Transfer the concentrated solution to a 250-mLseparator,with the aid of sufficient warm water to bring the volume to the original volume.Add 20g of sodium chloride,and shake until dissolved.Add 5mLof 1Nsodium hydroxide,shake with 100mLof ether,and drain the aqueous layer into a second separator containing 50mLof ether.Shake,and discard the aqueous layer.Wash the ether solutions with two 20-mLportions of water,shaking each aqueous portion successively in the two separators,and then discard the aqueous solutions.Extract the ether solutions successively with 10.0mLof 0.1Nsulfuric acid VS,followed by two 5-mLportions of water,and collect the aqueous extracts in a conical flask.Add methyl red TSto the solution in the flask,and titrate the excess acid with 0.02Nsodium hydroxide VS.Perform a blank determination (see
Residual Titrationsunder
Titrimetry á541ñ).Each mLof 0.1Nsulfuric acid is equivalent to 37.07mg of C
17H
20BrNO·HCl.