Fluorimetric determination of total ascorbic acid by a stopped-flow mixing technique.
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.
Pérez-Ruiz
T
T
Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, Spain. tpr@fcu.um.es
Martínez-Lozano
C
C
Tomás
V
V
Fenoll
J
J
Fenol
J
J
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
D004364:Pharmaceutical Preparations; D001205:Ascorbic Acid