Rev. Rul. 58-290

Section 212.57 of the Regulations relating to Formulas for Denatured Alcohol prescribes the use of brucine (alkaloid) or brucine sulfate in specially denatured alcohol Formula No. 40. However, as a result of a critical shortage of brucine and in accordance with the provisions of section 212.65 of the regulations, quassin, denaturing grade, in the amount of 1.5 avoirdupois ounces to each 100 gallons of ethyl alcohol, is authorized as a substitute denaturant for brucine (alkaloid) or brucine sulfate in the production of specially denatured alcohol Formula No. 40. Basic data concerning quassin are as follows:

Basic Data

Quassin -The bitter principle of quassia wood (occurring as a mixture of two isomeric forms).

Specifications -Quassin, Denaturing Grade. This shall be a good commercial grade of purified amorphous quassin, standardized as to bitterness by the following method:

When 0.4 gram is added to 20 ml of ethyl alcohol it shall dissolve completely. When 0.2 ml of this solution, measured from a burette is made up to 1 liter with water, the mixture shall have a distinctly bitter taste.

Identification Test -Dissolve about 0.5 gram quassin, denaturing grade, in 10 ml of 95 percent ethyl alcohol and filter. To 5ml of the filtrate add 5ml of concentrated hydrochloric acid and 1 mg phloroglucinol and mix well. A red color develops.

Optical Assay -When 1 gram of quassin, denaturing grade, is dissolved in 10,000 ml of water, the absorbance of the solution in a 1cm. cell at a wavelength of 258 millicrons shall be not less than 0.550 (for convenience of solution initially dissolve the quassin in a small amount of 95 percent alcohol).