title: Fluorimetric determination of total ascorbic acid by a stopped-flow mixing technique.
abstract: A simple, rapid and automatic fluorimetric method for the determination of total ascorbic acid is described. The method makes use of the stopped-flow mixing technique in order to achieve the rapid oxidation of ascorbic acid by dissolved oxygen to dehydroascorbic acid, which then reacts with o-phenylenediamine to form a fluorescent quinoxaline. The initial rate and fluorescence signal of this system are directly proportional to the ascorbic acid concentration. The calibration graph was linear over the range 0.1-30 microg ml(-1) (kinetic method) and 0.25-34 microg ml(-1) (equilibrium method). The precision (% RSD) was close to 0.5%. The method has been used for the determination of ascorbic acid in pharmaceutical formulations, fruit juices, soft drinks and blood serum.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, Spain. tpr@fcu.um.es
authors.forename: T
authors.initials: T
authors.lastname: Pérez-Ruiz
authors.forename: C
authors.initials: C
authors.lastname: Martínez-Lozano
authors.forename: V
authors.initials: V
authors.lastname: Tomás
authors.forename: J
authors.initials: J
authors.lastname: Fenoll
authors.forename: J
authors.initials: J
authors.lastname: Fenol
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis* / Q000097:blood; D001628:Beverages / Q000032:analysis; D017022:Flow Injection Analysis / Q000379:methods; D005470:Fluorometry / Q000379:methods; D005638:Fruit / Q000737:chemistry; D006801:Humans; D004364:Pharmaceutical Preparations / Q000737:chemistry
chemical_list: D004364:Pharmaceutical Preparations; D001205:Ascorbic Acid