title: Amperometric detection of benzoyl peroxide in pharmaceutical preparations using carbon paste electrodes with peroxidases naturally immobilized on coconut fibers.
abstract: This paper describes the applications of a new carbon paste electrode containing fibers of coconut (Cocus nucifera L.) fruit, which are very rich in peroxidase enzymes naturally immobilized on its structure. The new sensor was applied for the amperometric quantification of benzoyl peroxide in facial creams and dermatological shampoos. The amperometric measurements were performed in 0.1 mol L(-1) phosphate buffer (pH 5.2), at 0.0 V (versus Ag/AgCl). On these conditions, benzoyl peroxide was rapidly determined in the 5.0-55 micromol L(-1), with a detection limit of 2.5 micromol L(-1) (s/n=3), response time of 4.1 s (90% of the steady state) and sensitivity limit of 0.33 A mol L(-1) cm(-2). The amperometric results are in good agreement with those obtained by spectrophotometric technique, used as a standard method.
authors.affiliation: Departamento de Química, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: J V B
authors.initials: JV
authors.lastname: Kozan
authors.forename: R P
authors.initials: RP
authors.lastname: Silva
authors.forename: S H P
authors.initials: SH
authors.lastname: Serrano
authors.forename: A W O
authors.initials: AW
authors.lastname: Lima
authors.forename: L
authors.initials: L
authors.lastname: Angnes
mesh_terms: D001585:Benzoyl Peroxide / Q000032:analysis / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D003059:Cocos / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D009824:Ointments; D010544:Peroxidases / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D004800:Enzymes, Immobilized; D009824:Ointments; D004364:Pharmaceutical Preparations; D002244:Carbon; D010544:Peroxidases; D001585:Benzoyl Peroxide