Iron 3 chloride hexahydrate

HPLC 99% pure methanol was purchased from Honeywell (Paris, France). Folin-Ciocalteau (FC) reagent was obtained from Fisher Scientific UK (Loughborough, UK). Sodium carbonate, anhydrous (99.5–100.5%), sulfuric acid (96%, p.a.), hydrochloric acid (37%, w/w), and formic acid (98%, p.a.) were obtained from Lach-Ner (Neratovice, Czech Republic). Ethanol (96% pure) was purchased from Gram-mol (Zagreb, Croatia). Quercetin (95%) was purchased from Acros Organics (Guangzhou, China). Vanillin (99%) and chlorogenic acid (min. 95%) were obtained from Thermo Fisher (Kandel, Germany). DPPH (2,2-diphenyl-1-picrylhydrazyl radical), gallic acid standard (97.5–102.5%), and TPTZ (2,4,6-tris-2-pyridyl-s-triazine) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Iron (III)-chloride hexahydrate and sodium acetate trihydrate resistant to potassium permanganate were obtained from Kemika (Zagreb, Croatia). Glacial acetic acid (≥99.8%) was purchased from Honeywell Fluka^TM (Seelze, Germany), and Trolox standard (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) used for FRAP and DPPH assay was purchased from Biosynth (Bratislava, Slovakia).

Reagents used in this study were HPLC grade methanol (J.T. Baker, Radnor, PA, USA), HPLC grade acetonitrile (VWR, Radnor, PA, USA), Folin–Ciocalteu reagent (Sigma-Aldrich, St. Louis, MO, USA), 6% (w/v) anhydrous sodium carbonate (Gram-Mol, Zagreb, Croatia), 2,2-Diphenyl-1-picrylhydrazyl (DPPH) (Sigma-Aldrich, St. Louis, MO, USA), sodium acetate trihydrate (Lach-Ner, Neratovice, Czechia), 2,4,6-Tris(2-pyridyl)-s-triazine (TPTZ) (Alfa Aesar, Ward Hill, MA, USA), glacial acetic acid (Macron Fine Chemicals, Radnor, PA, USA), concentrated hydrochloric acid (Carlo Erba, Cornaredo, Italy), iron (III) chloride hexahydrate (Kemika, Zagreb, Croatia), fluorescein disodium salt (Alfa Aesar, Ward Hill, MA, USA), 2,2′-azobis(2-methylpropionamidine) dihydro-chloride (AAPH) (Acros Organics, Geel, Belgium), potassium dihydrogen phosphate (Gram-Mol, Zagreb, Croatia), dipotassium hydrogen phosphate (Gram-Mol, Zagreb, Croatia), trichloroacetic acid (TCA) (VWR, Radnor, PA, USA), and 2-thiobarbituric acid (TBA) (Alfa Aesar, Ward Hill, MA, USA). Chemicals used as standards were gallic acid (Acros Organics, Geel, Belgium), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Sigma-Aldrich, St. Louis, MO, USA), and L-proline (Alfa Aesar, Ward Hill, MA, USA).

HPLC 99% pure methanol obtained from Honeywell (Paris, France) was used as an extraction solvent, while the Folin–Ciocalteu reagent obtained from Fisher Scientific UK (Loughborough, UK) was used for spectrophotometric determination of total phenols. Hydrochloric acid (37%, w/w), sulfuric acid (96%, p.a.), sodium carbonate, anhydrous (99.5–100.5%), and formic acid (98%, p.a.) were obtained from Lach-ner (Neratovice, Czech Republic). Ethanol (96% pure) was obtained from Gram-mol (Zagreb, Croatia). Quercetin (95%), potassium acetate (99%), and aluminum chloride (98.5%) were purchased from Acros Organics (Guangzhou, China). Gallic acid standard (97.5–102.5%), DPPH (2,2-diphenyl-1-picrylhydrazyl radical), and TPTZ (2,4,6-tris-2-pyridyl-s-triazine) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Vanillin (99%), potassium chloride (99.0–100.5%), sodium acetate anhydride (99%), and chlorogenic acid (min. 95%) were purchased from Thermo Fisher (Kandel, Germany). Iron (III)-chloride hexahydrate and sodium acetate trihydrate resistant to potassium permanganate were obtained from Kemika (Zagreb, Croatia). Glacial acetic acid (≥99.8%) was purchased from Honeywell Fluka ^TM (Seelze, Germany) and trolox standard (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) used for the DPPH and FRAP method was purchased from Biosynth (Bratislava, Slovakia).