Sodium phosphate

Fresh beef and pork meat (loin) and pork back fat were obtained from a local meat market. Sunflower oil (Urzante S.L, Navarra, Spain) was obtained in a local market.
Carrageenan (kappa-carrageenan) was kindly donated by Cargill (San Sebastián, Spain).
Cholesterol, 5α-cholestane, thiobarbituric acid, fatty acid methyl esters and Polysorbate 80 were purchased from Sigma-Aldrich Chemical (Steinheim, Germany). 19hydroxycholesterol was obtained from Steraloids (Wilton, NH, USA). Tri-sil® reagent was obtained from Pierce (Rockford, IL, USA). Acetone, chloroform, ethyl acetate, methanol, hexane, 2-propanol, hydrochloric acid, cyclohexanone, trichloroacetic acid, potassium chloride, potassium hydroxide, anhydrous sodium sulphate and sodium phosphate were obtained from Panreac (Barcelona, Spain). hexane for gas chromatography, dichloromethane for gas chromatography and boron trifluoride/methanol were from Merck (Whitehouse Station, NJ, USA). Strata NH 2 (55 µm, 70 A) 500 mg/3 mL Solid Phase Extraction cartridges were obtained from Phenomenex (Torrance, CA, USA).

Cholesterol, stigmasterol, 5α-cholestane, heptadecanoic acid, α-tocopherol, tocopherol acetate, ammonium thyocianate and thiobarbituric acid were purchased from Sigma-Aldrich Chemical (Steinheim, Germany). 19-hydroxyCholesterol was obtained from Steraloids (Wilton, NH, USA). Tri-sil ® reagent was obtained from Thermo-Scientific (Rockford, IL, USA). Hexane, heptane, acetone, chloroform, ethyl acetate, butanol, methanol, 2-propanol, hydrochloric acid, cyclohexanone, trichloroacetic acid, potassium chloride, potassium hydroxide, ammonium iron (II) sulphate, barium chloride, anhydrous sodium sulphate and sodium phosphate were obtained from Panreac (Barcelona, Spain). Strata NH 2 (55 µm, 70 A) 500 mg / 3 mL Solid Phase Extraction cartridges were obtained from Phenomenex (Torrance, USA). Sunflower oil was purchased in a major local distributor.

The sterols reference standards squalene ([57-87-4] , ≥ 95%, [Buchs, Switzerland]), and lanosterol ([79-63-0], ≥ 93%, [Missouri, US]) were supplied by Sigma-Aldrich. Methanol was purchased from AppliChem Panreac (Barcelona, Spain), hexane was obtained from Merck KGaA (Germany) and chloroform was purchased from Quimipur (Madrid, Spain). Sodium chloride and sodium phosphate for buffer solution were obtained from Panreac (Barcelona, Spain).