title: Optimization of a CUPRAC-Based HPLC Postcolumn Assay and Its Applications for Ginkgo biloba L. Extracts.
abstract: The aim of the present work was to improve and validate the HPLC-CUPRAC postcolumn method for the evaluation of active antioxidant markers from the acetonic extracts of Ginkgo biloba leaves. Improvement of the HPLC online assay was performed by evaluating the suitable loop temperature, the reaction loop length, and the impact of flow rate. Separation of the analytes was performed by the HPLC method on an ACE C18 analytical column using a gradient elution program. The separated antioxidant markers in the extracts reacted with copper(II)-neocuproine (Cu(II)-Nc) reagent in the postcolumn reaction coil. The reagent was reduced by antioxidants to the copper(I)-neocuproine (Cu(I)-Nc) chelate with a maximum absorption at 450 nm. Validation experiments confirmed sufficient precision, sensitivity, and effectiveness of the corresponding method, which could be used for further evaluations of active antioxidant compounds in similar plant materials.
authors.affiliation: Department of Analytical and Toxicological Chemistry, Faculty of Pharmacy, Medical Academy of Lithuanian University of Health Sciences, Eiveniu Street 4, LT-50161 Kaunas, Lithuania.
authors.forename: Laura
authors.initials: L
authors.lastname: Rimkiene
authors.affiliation: Department of Analytical and Toxicological Chemistry, Faculty of Pharmacy, Medical Academy of Lithuanian University of Health Sciences, Eiveniu Street 4, LT-50161 Kaunas, Lithuania.
authors.forename: Liudas
authors.initials: L
authors.lastname: Ivanauskas
authors.affiliation: Department of Analytical and Toxicological Chemistry, Faculty of Pharmacy, Medical Academy of Lithuanian University of Health Sciences, Eiveniu Street 4, LT-50161 Kaunas, Lithuania.
authors.forename: Asta
authors.initials: A
authors.lastname: Kubiliene
authors.affiliation: Department of Analytical and Toxicological Chemistry, Faculty of Pharmacy, Medical Academy of Lithuanian University of Health Sciences, Eiveniu Street 4, LT-50161 Kaunas, Lithuania.
authors.forename: Konradas
authors.initials: K
authors.lastname: Vitkevicius
authors.affiliation: Department of Analytical and Toxicological Chemistry, Faculty of Pharmacy, Medical Academy of Lithuanian University of Health Sciences, Eiveniu Street 4, LT-50161 Kaunas, Lithuania.
authors.forename: Guoda
authors.initials: G
authors.lastname: Kiliuviene
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Medical Academy of Lithuanian University of Health Sciences, Eiveniu Street 4, LT-50161 Kaunas, Lithuania.
authors.forename: Valdas
authors.initials: V
authors.lastname: Jakstas