Ferric trichloride hexahydrate fecl3 6h2o

The FRAP (ferric-reducing ability of plasma) assay was performed according to the adapted method of Benzie and Strain [81 (link)] with respect to its latest modification by Bartoń, Fołta, and Zachwieja [82 ]. The working reagent of FRAP was prepared as a mixture of (1) acetic buffer (pH = 3.6), (2) TPTZ (2,4,6-Tris(2-pyridyl)-s-triazine) (Sigma-Aldrich, St. Louis, MO, USA), and (3) ferric trichloride hexahydrate (FeCl₃·6H₂O) (Sigma-Aldrich, St. Louis, MO, USA) in the following ratio: 2:1:1. Ferric (FeIII)-to-ferrous (FeII) ion reduction created an intensive blue color of the FeII–TPTZ complex with the absorbance maximum at 593 nm. A Multi-Detection Microplate Reader (Synergy 2, BioTek Instruments, Inc., Winoosoki, VT, USA) was used to perform analysis. The assay was conducted at 37 °C. An acetate buffer of 0.400 mL was dispensed into each well while 0.050 mL of the methanol–acetone extracts (3.2.3.) were pipetted, and 0.2 mL of the working FRAP reagent were then added. Absorbance was measured at ca. 1.5 min intervals within 60 min after addition of the working FRAP reagent. The method was calibrated by the use of the ferrous sulfate heptahydrate (Fe₂SO₄·7H₂O) (Sigma-Aldrich, St. Louis, MO, USA) standard solution at the concentration range of 0–1.5 mmol·L⁻¹.

All chemicals were of the highest purity (≥99.0%). Ferric chloride, Dragendorff's reagent, magnesium metal strips, gallic acid, ascorbic acid, catechin, Folin-Ciocalteu reagent, sodium carbonate, vanillin, aluminium chloride, phosphate buffer, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,4,6-tripyridyl-s-triazine (TPTZ), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), potassium persulfate, and ferric trichloride hexahydrate (FeCl₃·6H₂O) were all purchased from Sigma Aldrich, USA. Hydrochloric acid (HCl), methanol, chloroform, 98% sulfuric acid, and glacial acetic acid were all analytical grade and purchased from Merck, Germany.