title: Use of the triiodide-cetylpyridinium chloride micellar system for the determination of benzoyl peroxide in pharmaceutical preparations.
abstract: A kinetic spectrophotometric method for the determination of benzoyl peroxide in acne preparations is proposed. The method is based on the reduction of benzoyl peroxide by iodide in the cationic micellar medium provided by cetylpyridinium chloride (CPC). The triiodide ion produced associates with CPC micelles, which gives rise to an absorption maximum at 500 nm in addition to substantially increased absorptivity and stability constant for the triiodide complex. Acne preparations can be analyzed directly after dissolution of the samples in ethanol. The detection limit thus achieved is 0.033 microgram.mL-1, so the proposed method surpasses existing alternative methods in sensitivity. The relative standard deviation for 0.25 microgram.mL-1 is 2.1%.
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, University of Córdoba, Spain.
authors.forename: M L
authors.initials: ML
authors.lastname: Lunar
authors.forename: S
authors.initials: S
authors.lastname: Rubio
authors.forename: D
authors.initials: D
authors.lastname: Pérez-Bendito
mesh_terms: D000152:Acne Vulgaris / Q000188:drug therapy; D001585:Benzoyl Peroxide / Q000032:analysis*; D002594:Cetylpyridinium / Q000737:chemistry*; D003879:Dermatologic Agents / Q000032:analysis; D007454:Iodides / Q000737:chemistry*; D007700:Kinetics; D008823:Micelles; D010783:Photometry; D013055:Spectrophotometry, Infrared
chemical_list: D003879:Dermatologic Agents; D007454:Iodides; D008823:Micelles; D002594:Cetylpyridinium; D001585:Benzoyl Peroxide