Determination of antioxidants by a novel on-line HPLC-cupric reducing antioxidant capacity (CUPRAC) assay with post-column detection

Analytica Chimica Acta
S Esin CelikReşat Apak

Abstract

A novel on-line HPLC-cupric reducing antioxidant capacity (CUPRAC) method was developed for the selective determination of polyphenols (flavonoids, simple phenolic and hydroxycinnamic acids) in complex plant matrices. The method combines chromatographic separation, constituent analysis, and post-column identification of antioxidants in plant extracts. The separation of polyphenols was performed on a C18 column using gradient elution with two different mobile phase solutions, i.e., MeOH and 0.2% o-phosphoric acid. The HPLC-separated antioxidant polyphenols in the extracts react with copper(II)-neocuproine (Cu(II)-Nc) reagent in a post-column reaction coil to form a derivative. The reagent is reduced by antioxidants to the copper(I)-neocuproine (Cu(I)-Nc) chelate having maximum absorption at 450 nm. The negative peaks of antioxidant constituents were monitored by measuring the increase in absorbance due to Cu(I)-Nc. The detection limits of polyphenols at 450 nm (in the range of 0.17-3.46 microM) after post-column derivatization were comparable to those at 280 nm UV detection without derivatization. The developed method was successfully applied to the identification of antioxidant compounds in crude extracts of Camellia sinensis, ...Continue Reading

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Citations

May 12, 2011·Analytical Sciences : the International Journal of the Japan Society for Analytical Chemistry·Joana P N RibeiroMarcela A Segundo
Apr 11, 2012·International Journal of Molecular Sciences·Christiaan J MalherbeElizabeth Joubert
Oct 26, 2011·Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy·Baki TürkkanReşat Apak
Jun 1, 2011·Clinical and Experimental Allergy : Journal of the British Society for Allergy and Clinical Immunology·A SinghA Mercenier
Aug 14, 2012·Journal of the Science of Food and Agriculture·Seyda KaramanReşat Apak
Nov 26, 2015·Food Chemistry·Zhuo ZouZhiqin Zhou
Nov 18, 2015·Critical Reviews in Analytical Chemistry·Andrei A BunaciuHassan Y Aboul-Enein
Aug 4, 2015·Journal of Analytical Methods in Chemistry·Laura RimkieneValdas Jakstas
Jul 2, 2019·Journal of Agricultural and Food Chemistry·Reşat Apak

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