Code of Federal Regulations Title 21. Food and Drugs § 21.173.395 Trifluoromethane sulfonic acid

(a) The catalyst meets the following specifications:

Appearance, Clear liquid.

Color, Colorless to amber.

Neutralization equivalent, 147–151.

Water, 1 percent maximum.

Fluoride ion, 0.03 percent maximum.

Heavy metals (as Pb), 30 parts per million maximum.

Arsenic (as As), 3 parts per million maximum.

(b) It is used at levels not to exceed 0.2 percent of the reaction mixture to catalyze the directed esterification.

(c) The esterification reaction is quenched with steam and water and the catalyst is removed with the aqueous phase. Final traces of catalyst are removed by washing batches of the product three times with an aqueous solution of 0.5 percent sodium bicarbonate.

(d) No residual catalyst may remain in the product at a detection limit of 0.2 part per million fluoride as determined by the method described in “Official Methods of Analysis of the Association of Official Analytical Chemists,” sections 25.049–25.055, 13th Ed. (1980), which is incorporated by reference. Copies may be obtained from the AOAC INTERNATIONAL, 481 North Frederick Ave., suite 500, Gaithersburg, MD 20877, or may be examined at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202–741–6030, or go to:  http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.