Ethanolic potassium hydroxide— Dissolve about 5.5g of potassium hydroxide in absolute alcohol,heating if necessary to effect solution,and dilute with absolute alcohol to about 1000mL.Prepare fresh daily,and filter if necessary to remove carbonate.

Procedure— Transfer about 450mg of Sodium Stearyl Fumarate,accurately weighed,to a 300-mLconical flask,and add 50.0mLof Ethanolic potassium hydroxide,rinsing down the inside of the flask during the addition.Gently reflux the mixture on a steam bath for not less than 2hours,swirling gently occasionally,but avoid splashing the mixture up into the condenser.Rinse the condenser with 10mLof 70percent alcohol,followed by three 10-mLportions of water,collecting the rinsings in the flask.Cool,rinse the sides of the flask with two 10-mLportions of 70percent alcohol,add phenolphthalein TS,and titrate with 0.1Nhydrochloric acid VSto the disappearance of any pink color.Perform a blank determination,using the same volume of Ethanolic potassium hydroxide.The difference between the volumes,in mL,of 0.1Nhydrochloric acid consumed in the actual test and in the blank test,multiplied by 5.61and divided by the weight,in g,of specimen taken,is the Saponification value.It is between 142.2and 146.0,calculated on the anhydrous basis.

Standard monostearyl maleate preparation— Using a mixture of chloroform and glacial acetic acid (4:1)as solvent,prepare a solution of USP Monostearyl Maleate RScontaining 1mg per mL.Pipet 5mLof this solution into a 50-mLvolumetric flask,dilute with chloroform to volume,and mix.

Standard stearyl alcohol preparation— Using a mixture of chloroform and glacial acetic acid (4:1)as solvent,prepare a solution of USP Stearyl Alcohol RScontaining 1mg per mL.Pipet 5mLof this solution into a 50-mLvolumetric flask,dilute with chloroform to volume,and mix.

Test preparation— Weigh 200mg of Sodium Stearyl Fumarate into a small,glass-stoppered conical flask.Add 10.0mLof a mixture of chloroform and glacial acetic acid (4:1).Dissolve by placing the flask in an ultrasonic bath for about 10minutes.

Procedure— Apply 5µLof Standard monostearyl maleate preparationand 10µLeach of Standard stearyl alcohol preparationand Test preparationseparately to a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Immerse the plate in a tank containing a layer of about 10mm of chloroform on the bottom.Allow the solvent front to reach the upper edge of the spots.Withdraw the plate,and dry in a current of cold air.Repeat the immersion,development,and drying.This results in spots having a linear shape.Develop the chromatograph in a saturated chamber containing a solvent system consisting of a mixture of hexanes,toluene,and glacial acetic acid (50:50:10)until the solvent front has moved 15cm,and remove the plate from the chamber.Allow to dry for 10minutes,and heat in an oven at 90for 2minutes.Allow to cool to room temperature.Replace the plate into the chamber for another 15-cm development,remove the plate,and allow to dry at room temperature for 15minutes.Spray the plate carefully with a solution prepared by adding,cautiously and with stirring,10mLof sulfuric acid to 90mLof alcohol.Dry the plate in an oven at 150for 15minutes.Dark spots appear on a light background.Allow to cool.Faint spots at an RFvalue of about 0.9may result from traces of distearyl maleate and distearyl fumarate.The intensity of any spot from the Test preparationis not greater than that from the corresponding spot from the Standard preparation(0.25%sodium stearyl maleate,0.5%stearyl alcohol).

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