2 2 azino bis 3 ethylbenzthiazoline 6 sulphonic acid diammonium salt abts

Blackberries (Rubus fruticosus spp.) were obtained from a local market in Atotonilco, Hidalgo, México, during the winter of 2014. Folin–Ciocalteu 2 N reagent (Sigma-Aldrich, St. Louis, MO, USA), anhydrous sodium carbonate (Meyer, Tláhuac, DF, Mexico), gallic acid (Meyer), potassium chloride (Sigma-Aldrich), anhydrous sodium acetate (Meyer), hydrochloric acid (Reasol, Iztapalapa, DF, Mexico), 2,2′azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) ≥ 98% (Sigma-Aldrich), potassium persulfate crystals (Meyer), Trolox 97% (Sigma-Aldrich), absolute ethanol (Meyer), 1,1-di-phenyl-2-picrylhydrazyl (DPPH) (Sigma-Aldrich). All chemicals and reagents used in the study were of analytical grade (AG).

Hydrochloric acid (Panreac, Barcelona, Spain), methyltrimetoxisilane (MTMOS) (Merck, Darmstadt, Germany), graphite powder UF (Alfa Aesar, Karlsruhe, Germany), sulfuric acid (Merck), 3,4-ethylenedioxythiophene (Sigma-Aldrich, Steinheim, Germany), potassium dihydrogen phosphate (Merck), di-potassium hydrogen phosphate (Panreac, Barcelona, Spain), Tyrosinase (E.C. 1.14.18.1, from mushroom, 3610 units/mg solid, Sigma-Aldrich, Steinheim, Germany), potassium hexacyanoferrate (II) (Sigma-Aldrich, Steinheim, Germany), potassium hexacyanoferrate (III) (Sigma-Aldrich, Steinheim, Germany), caffeic acid (Sigma-Aldrich, Steinheim, Germany), hexan-1-ol (Panreac, Barcelona, Spain), 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) (Sigma-Aldrich, Steinheim, Germany) and potassium peroxydisulphate (Panreac, Barcelona, Spain) were used as received, without further purification.
All aqueous solutions were prepared with nanopure water which was obtained by passing twice-distilled water through a Milli-Q system (18 MΩ cm, Millipore, Bedford, MA, USA).

Kraft lignin (L) was kindly provided by ENCE (Pontevedra, Spain). It was obtained by acid precipitation from black liquor originated during kraft cooking of Eucalyptus globulus and presented a purity of 98.2%. Montmorillonite (M) was supplied by Southern Clay Products and corresponds to the commercial product known as Cloisite®Na⁺. It is a Wyoming-type Na-montmorillonite with ideal formula Na_0.33[(AlMg)₂(Si₄O₁₀)(OH)₂]·nH₂O and cation exchange capacity (CEC) of 93 mEq/100 g.^{16 (link)} Hydroxypropyl methylcellulose (HPMC; ∼22 kDa; methoxyl content: 28–20%, hydroxypropoxyl content: 7–12%), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) and other chemicals used here were purchased from Sigma-Aldrich (Madrid, Spain), being used as received, i.e. without further treatments.