The antioxidant activity of teas measured by the FRAP method adapted to the FIA system: Optimising the conditions using the response surface methodology |
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Authors: | Alessandro C Martins Lais BukmanAlexandro MM Vargas Érica O BarizãoJuliana CG Moraes Jesuí V VisentainerVitor C Almeida |
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Affiliation: | Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo, 5790, CEP 87020-900 Maringá, Paraná, Brazil |
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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 Fe2+, 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. |
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Keywords: | Flow injection analysis (FIA) Response surface methodology Antioxidant activity Tea |
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