Aceton

Disodium hydrogen phosphate dodecahydrate was purchased from Bernd Kraft GmbH (Duisburg, Germany). Sodium dihydrogen phosphate monohydrate was from AppliChem GmbH (Darmstadt, Germany) and catechol was from ThermoFisher GmbH (Kandel, Germany). Aceton was used from VWR International LLC (Fontenay-sous-Bois, France). The standards for the HPLC analysis (chlorogenic acid, catechin, epicatechin, phloretin-2-glucoside, and quercetin 3-glucoside) and hydrochloric acid (25%) were from Carl Roth GmbH & Co. KG (Karlsruhe, Germany). Sodium carbonate was purchased from Grüssing GmbH (Filsum, Germany) and potassium peroxodisulphate was from Fisher Scientific UK Ltd. (Loughborough, UK). Folin-Ciocalteu’s phenol reagent, potassium dihydrogen phosphate, and nitric acid (65%) were purchased from Merck KgaA (Darmstadt, Germany). Galllic acid and 2,2’-azobis(2-methylpropionamidine) dihydrochloride were from Fisher Scientific GmbH (Schwerte, Germany). 2,2’-Azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt, trolox, and fluorescein were purchased from Sigma-Aldrich Chemie GmbH (Deisenhofen, Germany). All of the chemicals were of analytical grade. Water was purified through a Milli-Q water system (PURELAB^®, Elga LabWater, Veolia Water Technologies GmbH, Celle, Germany) and was used for buffers, the extracting agents, and dilution of sample extracts.

Analytical standard of ENN B was purchased from Fermentek (Jerusalem, Israel). The internal standard (IS) [¹⁵N₃]-ENN B was synthesized according to Hu and Rychlik (2012) [17 (link)]. ENN B and the IS were stored at ≤−15 °C. Glacial acetic acid, water, methanol, and Acetonitrile were of LC-MS grade (Biosolve, Valkenswaard, The Netherlands). Aceton was purchased from VWR (Leuven, Belgium). Millex-GN nylon filters (0.20 µm) were purchased from Merck-Millipore (Merck-Millipore, Overijse, Belgium).