title: The antioxidant activity of teas measured by the FRAP method adapted to the FIA system: optimising the conditions using the response surface methodology.
abstract: This study proposes a FRAP assay adapted to FIA system with a merging zones configuration. The FIA system conditions were optimised with the response surface methodology using the central composite rotatable design. The optimisation parameters studied were: the carrier flow rate, the lengths of the sample and reagent loops, and reactor length. The conditions selected in accordance with the results were: carrier flow rate of 1.00 ml/min, length of the loops 18.2 cm and length of the reaction coil 210.1 cm. The detection and quantification limits were, respectively, 28.6 and 86.8 μmol/l Fe(2+), and the precision was 1.27%. The proposed method had an analytical frequency of 30 samples/h and about 95% less volume of FRAP reagent was consumed. The FRAP assay adapted to the FIA system under the optimised conditions was utilised to determine the antioxidant activity of tea samples.
authors.affiliation: Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo, 5790, CEP 87020-900 Maringá, Paraná, Brazil.
authors.forename: Alessandro C
authors.initials: AC
authors.lastname: Martins
authors.forename: Lais
authors.initials: L
authors.lastname: Bukman
authors.forename: Alexandro M M
authors.initials: AM
authors.lastname: Vargas
authors.forename: Érica O
authors.initials: ÉO
authors.lastname: Barizão
authors.forename: Juliana C G
authors.initials: JC
authors.lastname: Moraes
authors.forename: Jesuí V
authors.initials: JV
authors.lastname: Visentainer
authors.forename: Vitor C
authors.initials: VC
authors.lastname: Almeida
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D017022:Flow Injection Analysis / Q000379:methods*; D010084:Oxidation-Reduction; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005290:Ferric Compounds; D013662:Tea