Rubbing Alcohol
»Rubbing Alcohol and all preparations under the classification of Rubbing Alcohols are manufactured in accordance with the requirements of the U.S.Treasury Department,Bureau of Alcohol,Tobacco,and Firearms,Formula 23-H(8parts by volume of acetone,1.5parts by volume of methyl isobutyl ketone,and 100parts by volume of ethyl alcohol)being used.It contains not less than 68.5percent and not more than 71.5percent by volume of dehydrated alcohol,the remainder consisting of water and the denaturants,with or without color additives,and perfume oils.Rubbing Alcohol contains,in each 100mL,not less than 355mg of sucrose octaacetate or not less than 1.40mg of denatonium benzoate.The preparation may be colored with one or more color additives,listed by the FDAfor use in drugs.Asuitable stabilizer may be added.Rubbing Alcohol complies with the requirements of the Bureau of Alcohol,Tobacco,and Firearms of the U.S.Treasury Department.
NOTE—Rubbing Alcohol is packaged,labeled,and sold in accordance with the regulations issued by the U.S.Treasury Department,Bureau of Alcohol,Tobacco,and Firearms.
Packaging and storage— Preserve in tight containers,remote from fire,and store at controlled room temperature.
Labeling— Label it to indicate that it is flammable.
Specific gravity á841ñ: between 0.8691and 0.8771at 15.56(the U.S.Government standard temperature for alcohol determination),for Rubbing Alcohol manufactured with specially denatured alcohol Formula 23-H.
Limit of nonvolatile residue—
Where the denaturant is denatonium benzoate— Evaporate 200.0mLof Rubbing Alcohol,transferred in convenient portions,in a suitable tared dish on a steam bath,and dry the residue at 105for 1hour:the weight of the residue is not less than 2.8mg.(Retain the residue for the Assay for denatonium benzoate.)
Where the denaturant is sucrose octaacetate— Evaporate 25.0mLof Rubbing Alcohol in a suitable tared dish on a steam bath,and dry the residue at 105for 1hour:the weight of the residue is not less than 89mg.(Retain the residue for the Assay for sucrose octaacetate.)
Methanol— Dilute 0.50mLof it with water to 1.0mL.To 0.50mLof the resulting solution add 1drop of dilute phosphoric acid (1in 20)and 1drop of potassium permanganate solution (1in 20).Mix,allow to stand for 1minute,and add sodium metabisulfite solution (1in 20),dropwise,until the permanganate color is discharged.If a brown color remains,add 1drop of dilute phosphoric acid (1in 20).To the colorless solution add 5mLof freshly prepared chromotropic acid TS,and heat in a water bath at 60for 10minutes:no violet color appears.
Assay for denatonium benzoate—
Buffer solution— Dissolve 9.23g of anhydrous dibasic sodium phosphate in 800mLof water,adjust with saturated citric acid solution to a pHof 4±0.1,dilute with water to 1000mL,and mix.
Standard preparation— Dissolve about 25mg of USP Denatonium Benzoate RS,accurately weighed,in water to make 500mL,and mix.
Assay preparation— Dissolve the residue obtained in the test for Limit of nonvolatile residuein 50.0mLof water,and transfer to a suitable flask.
Procedure— Treat the Standard preparation,Assay preparation,and blank similarly and concomitantly.Transfer 10.0mLeach of the Standard preparation,Assay preparation,and Buffer solutionto individual 250-mLseparators,and add to each 40mLof Buffer solution,10mLof a 1in 1000solution of bromophenol blue in chloroform,and 60mLof chloroform.Shake the separators vigorously for 2minutes,allow to stand for 15minutes,then withdraw the chloroform layers through chloroform-washed cotton into 100-mLvolumetric flasks.Repeat the extraction with 20mLof chloroform,adding the filtered chloroform extracts to the respective volumetric flasks,dilute with chloroform to volume,and mix.Without delay,concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 410nm,with a suitable spectrophotometer,using the blank to set the instrument.Calculate the quantity,in mg,of denatonium benzoate (C28H34N2O3·H2O)in 100mLof Rubbing Alcohol taken by the formula:
in which Cis the concentration,in µg per mL,of USP Denatonium Benzoate RSin the Standard preparation;and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.
Assay for sucrose octaacetate— Using about 50mLof 70%alcohol,transfer the residue obtained in the test for Limit of nonvolatile residueto a 500-mLconical flask.Neutralize the solution with 0.1Nsodium hydroxide VS,using phenolphthalein TSas the indicator.Add 25.0mLof 0.1Nsodium hydroxide,attach an air condenser to the flask,and reflux on a steam bath for 1hour.Remove from the steam bath,cool quickly,and titrate the excess alkali with 0.1Nsulfuric acid VS,using phenolphthalein TSas the indicator.Perform a blank determination (see Residual Titrationsunder Titrimetry á541ñ).Each mLof 0.1Nsodium hydroxide is equivalent to 8.483mg of sucrose octaacetate (C28H38O19).
Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA2)Pharmaceutical Analysis 2
USP28–NF23Page 62
Pharmacopeial Forum:Volume No.27(3)Page 2507
Phone Number:1-301-816-8139