2 4 6 tris 2 pyridyl s triazine

Hydrochloric acid, n-hexane (HPLC grade) and Folin-Ciocalteu reagent were purchased from Carlo Erba Reagents (Val de Reuil, France), and sodium hydroxide and sodium nitrite from Gram-mol (Zagreb, Croatia), ferric chloride hexahydrate and sodium acetate trihydrate from T.T.T. (Sveta Nedelja, Croatia), and aluminum chloride hexahydrate from Kemika (Zagreb, Croatia). Sodium carbonate was supplied by Panreac Química (Castellar del Vallès, Spain), ferrous sulfate heptahydrate by Acros Organics (Madrid, Spain) and 2,4,6-Tris(2-pyridyl)-s-triazine (TPTZ) by Alfa Aesar (Karlsruhe, Germany). HPLC grade standards of theobromine, caffeine and (+)-catechin, (−)-epicatechin gallate, caffeic acid and p-coumaric acid, gallic acid and (−)-epicatechin were purchased from Sigma-Aldrich (St. Louis, MO, USA). Methanol (J.T. Baker, Deventer, The Netherlands) and formic acid (Scharlau Chemie, Spain) used for mobile phase preparation were HPLC grade.

Most of the reagents and reference standards were from Sigma-Aldrich (St. Louis, MO, USA) or VWR International (Darmstadt, Germany). The peptone water and tryptone glucose extract agar were obtained from Scharlau (Barcelona, Spain). The pseudomonas agar base and the supplement cetrimide-fucidin-cephaloridine were purchased from Oxoid (Basingstoke, UK). Food-grade sodium alginate was acquired from Quimidroga, s.a, Lisboa, Portugal with a 200 mesh particle size. The solvents used, ethanol and methanol, were purchased from Panreac (Barcelona, Spain). The 2,4,6-Tris(2-pyridyl)-s-triazine (TPZ) was purchased from Alfa Aesar (Tewksbury, MA, USA).