Acetonitrile, water, methanol, acetic acid and formic acid were LC-MS grade from VWR Prolabo (Fontenay sous Bois. France). Gallic acid, 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS), L-tartaric acid, ethanol, sodium hydroxide, potassium persulfate, βglucogallin, 1,2,3,4,6-pentagalloylglucose (PGG), methyl gallate, deuterated dimethylsulfoxide (DMSO-d6), deuterated pyridine (pyridine-d5), deuterated chloroform (CDCl3), 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane (cTMDP), lithium chloride, and hydrochloric acid 37 % were provided by Sigma-Aldrich (Saint Louis, MO, USA), and N,N-dimethylformamide by Carl Roth GmbH (Karsruhe, Germany).
Three commercial gallotannin extracts (TAN A, TAN B1, TAN B2), available in the powder form and sold to the wine industry with claims related to their antioxidant properties were analyzed.
Sample A was Tanal W2 (Ajioto Onmnichem, Wetteren, Belgium). Samples B1 and B2 correspond to two different batches of the same commercial brand (Tan'Activ GC, SilvaTeam, San Michele Mondovì, Italy). All three were stored in the dark in a desiccator until analysis.
Three commercial gallotannin extracts (TAN A, TAN B1, TAN B2), available in the powder form and sold to the wine industry with claims related to their antioxidant properties were analyzed.
Sample A was Tanal W2 (Ajioto Onmnichem, Wetteren, Belgium). Samples B1 and B2 correspond to two different batches of the same commercial brand (Tan'Activ GC, SilvaTeam, San Michele Mondovì, Italy). All three were stored in the dark in a desiccator until analysis.