title: Asynchronous merging zones system: spectrophotometric determination of Fe(II) and Fe(III) in pharmaceutical products.
abstract: An asynchronous merging zones was proposed with simultaneous introduction of the sample and of the modifier reagent, ascorbic acid in the studied case, for sequential determination of Fe(II) and Fe(III) in pharmaceutical products. The sample and reagent attained a merging point at different times owing to the use of a delay reactor in the reagent channel. By inserting a large sample and controlling the dispersion in the flow system, Fe(II) and Fe(III) were sequentially measured in the front and in the rear of the sample zone, respectively. The results obtained for Fe redox speciation in pharmaceutical products are in agreement at a 95% confidence level with those obtained with a manual spectrophotometric procedure. The analytical frequency with the proposed flow analysis system was 54 samples h(-1), i.e. 108 determinations h(-1).
authors.affiliation: Departamento de Quimica, Grupo de Quimica Analitica, Centro de Ciências Exatas e de Tecnologia, Universidade Federal de São Carlos, Caixa Postal 676, CEP 13.560-970, São Carlos, SP, Brazil.
authors.forename: A F
authors.initials: AF
authors.lastname: Oliveira
authors.forename: J A
authors.initials: JA
authors.lastname: Nóbrega
authors.forename: O
authors.initials: O
authors.lastname: Fatibello-Filho