Sodium carbonate anhydrous

All solvents used for the extractions of phenolic compounds from vinification by-products were purchased from Carlo Erba and Fisher Chemicals as analytical grade solvents. Solvents used for the LC-MS/MS determinations were obtained from J.T. Baker (water and acetonitrile) and Fisher Chemicals (formic acid) as LC–MS grade.
All standards used for the assessments of the phenolic compounds were obtained from Sigma-Aldrich (St. Louis, MO, USA), except epigallocatechin gallate and quercetin-3-β-D-glucoside that were provided by ExtraSynthese (Genay, France) and the acids coutaric, fertaric and caftaric, which were obtained from Phytolab (Vestenbergsgreuth, Germany), and ferulic acid bought from Fluka (Buchs, Switzerland). Folin-Ciocalteu’s reagent was purchased from Sigma-Aldrich, vanillin was obtained from Acros Organics (Geel, Belgium). Anhydrous sodium carbonate, sulfuric acid 98% and hydrochloric acid were purchased from Chem-Lab (Zedelgem, Belgium), glacial acetic acid from Sigma-Aldrich, hexahydrate aluminum chloride from Fluka (Buchs, Switzerland) and hydrate sodium acetate from Merck (Darmstadt, Germany).

All solvents used for the extractions of phenolic compounds from grapevines and vinification byproducts were purchased from Carlo Erba and Fisher Chemicals as analytical-grade solvents. Solvents used for the LC–MS/MS determinations were obtained as LC–MS grade from J.T. Baker (water and acetonitrile) and Fisher Chemicals (formic acid).
All standards used for the assessments of phenolic compounds were obtained from Sigma-Aldrich except epigallocatechin gallate and quercetin-3-β-D-glucoside, which were provided by Extra Synthese; coutaric, fertaric and caftaric acids, which were obtained from Phytolab; and ferulic acid, bought from Fluka. Folin–Ciocalteu’s reagent, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ) were purchased from Sigma-Aldrich, while 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) and vanillin were obtained from Acros Organics. Anhydrous sodium carbonate, sulfuric acid 98% and hydrochloric acid were purchased from Chem-Lab; glacial acetic acid from Sigma-Aldrich; hexahydrate aluminum chloride from Fluka; and hydrate sodium acetate from Merck. Hexahydrate ferric chloride and heptahydrate iron sulfate were obtained from Alfa Aesar.

Htyr (≥98%) was purchased from Extrasynthèse (Genay, France) and Tyr (≥98%) from Alfa Aesar GmdH & Co KG, (Karlsruhe, Germany), CA (98%) and DHPA (98%) were purchased from Sigma-Aldrich Chemie GmbH (Steinheim, Germany). Analytical-grade methanol, HPLC grade methanol, acetonitrile and water were obtained from ChemLab (Zeldegem, Belgium). Phosphoric acid (≥85%) and sulphuric acid (95–98%) were supplied by Sigma-Aldrich (Steinheim, Germany). Sodium carbonate anhydrous and Folin-Ciocalteu (F-C) reagent were obtained from ChemLab (Zeldegem, Belgium). Polyvinylidene fluoride (PVDF) membrane filters (0.22 µm) were from Schleicher & Schuell, (Dassel, Germany).