Hplc grade methanol and neocuproine

In this study, the following reagents and standards were used: aluminium chloride, quercetin dihydrate, gallic acid monohydrate, potassium persulfate, Trolox, 2,2-azinobis(3-ethylbenzothiazoline sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazil (DPPH), 2,4,6-tripyridyl-s-triazine (TPTZ) were obtained from Sigma-Aldrich (St. Lois, MO, USA); HPLC standards (gallic and caffeic acid, (+)-catechin hydrate, (−)-epicatechin, rutin hydrate, quercetin) were purchased from Sigma-Aldrich Chemie Gmbh (Steinheim, Germany), and malvidin 3-glucoside from Extrasynthese (Genay, France). Folin–Ciocalteu reagent, sodium nitrite, sodium carbonate, sodium hydroxide, potassium bisulphite, sodium acetate, potassium chloride and hydrochloric acid were purchased from Kemika (Zagreb, Croatia); sodium acetate trihydrate, ferric chloride hexahydrate, and ammonium acetate were purchased from Gram-Mol (Zagreb, Croatia); copper(II) chloride from Acros Organics (New Jersey, NJ, USA); HPLC grade methanol and neocuproine from Merck (Darmstadt, Germany) and phosphoric acid (HPLC grade) were obtained from Fluka (Buchs, Switzerland).