Sodium hydrogen carbonate

Acetone and ethanol were purchased from Carl Roth. Acetonitrile, 2,2-dimethoxypropane, p-toluenesulfonic acid, tetrahydrofuran and sodium chloride (98%) were purchased from Sigma Aldrich (Taufkirchen, Germany). Acryloyl chloride (96%) was purchased from Merck (Darmstadt, Germany). Azobis(isobutyronitril) (98%), triethylamine and trifluoroacetic acid were purchased from Acros Organics (Geel, Belgium). Dichlormethane, diethylether, ethyl acetate, methanol, hexane and dimethylformamide were purchased from VWR Prolabo (Darmstadt, Germany). Dopamine hydrochloride (99.96%) and glycinamide hydrochloride were purchased from BLD Pharmatech (Kaiserslautern, Germany). Hydroquinone was purchased from J.T. Baker (Phillipsburg, NJ, USA). Potassium carbonate, lithium hydroxide and magnesium sulfate were purchased from Fisher Scientific. Methyl trifluoroacetate was purchased from Fluorochem (Hadfield, UK). N-[3-(Dimethylamino)propyl]acrylamide (98%) and N-(2-hydroxyethyl)acrylamide (98%) were purchased from TCI (Tokyo, Japan). Sodium hydrogencarbonate, hydrochloric acid (37%) and toluene were purchased from VWR Chemicals.

ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), Trolox (6-hydroxyl-2,5,7,8-tetramethylchroman-2-carboxylic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl), TFA (trifluoroacetic acid), gallic acid, Folin–Ciocalteu reagent (FC), pepsin from porcine gastric mucosa-lyophilized powder, α-amylase and pancreatin from porcine pancreas, heat-stable α-amylase solution, protease, amyloglucosidase solution, 2-(N-Morpholino) ethanesulfonic acid (MES), and Tris (hydroxymethyl) aminomethane (TRIS) were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). Technical grades of methanol (MeOH) (>98.5%), ethanol (C₂H₅OH) (93%), sodium hydroxide (NaOH) (97%), sodium chloride (NaCl) (97%), potassium persulfate (K₂S₂O₈) (100%), sodium carbonate (Na₂CO₃) (>99%), nitric acid (HNO₃) (>99%), sulfuric acid (H₂SO₄) (>97%), hydrochloric acid (HCl) (37.2% w/w), petroleum ether (C₆H₁₄) (30–60 °C, A.R), Kjeldahl tablet (CuH₁₀O₉S), potassium chloride (KCl) (> 99%), sodium hydrogen carbonate (NaHCO₃) (>99%), sodium chloride (NaCl) (97%), magnesium chloride (MgCl₂) (99%), ammonium chloride (NH₄Cl) (100%), calcium chloride (CaCl₂) (>93%), monopotassium phosphate (KH₂PO₄), and indicators (tashiro and phenolphthalein) were purchased from VWR International (Leuven, Belgium). Inductively coupled plasma (ICP) multi-element standard solution IV was procured from Merck KGak (Darmstadt, Germany).

HPLC grade methanol, acetone, and methyl tert-butyl ether were acquired from Fisher Scientific Scharlau Chemie (Loughborough, UK). Sodium chloride was purchased from POCH S.A. (Sowińskiego, Poland). Ultrapure water was obtained with a Milli-Q system (Millipore Ibérica, Madrid, Spain). Ammonium carbonate, acetonitrile, hexane, ethanol (HPLC grade), magnesium chloride hexahydrate, acetic acid, and ammonium acetate were acquired from Scharlab (Sentmenat, Spain). Butyl hydroxytoluene (BHT) was purchased from Scharlau Chemie S.A. (Barcelona, Spain). Calcium chloride dihydrate was obtained from Merck (Darmstadt, Germany). Sodium hydrogen carbonate and potassium dihydrogen phosphate were acquired from VWR (Llinars del Vallès, Spain). Potassium chloride was obtained from Panreac (Castellar del Vallès, Spain). Digestive enzymes (porcine pepsin, porcine bile extract, porcine pancreatin, and porcine lipase) were acquired from Sigma-Aldrich (Darmstadt, Germany).
Caffeic acid, ferulic acid, and p-coumaric acid commercial patterns were obtained from Sigma-Aldrich (St. Louis, MO, USA). B-carotene standard was acquired from Carote-Nature (Ostermundigen, Switzerland), and α-carotene was acquired from Supelco-Merck (Darmstadt, Germany).