1 3 olein 2 palmitin

Regiopure TAG standards 1,2-olein-3-palmitin (OOP), 1,3-olein-2-palmitin (OPO), 1,2-olein-3-stearin (OOS), and 1,3-olein-2-stearin (OSO) were purchased from Larodan (Solna, Sweden). Solvents used for milk lipid extraction and mobile phase preparation were of MS or HPLC grade. Methanol and isopropanol were from Fisher Scientific (Ottawa, Canada), chloroform from Sigma-Aldrich (St. Louis, MO, USA), and acetonitrile and butanol from Merck (Kenilworth, NJ, USA). Ammonium formate (used as a mobile phase additive) was of analytical grade (Sigma-Aldrich, St. Louis, MO, USA).

A standard mixture of 37 FAMEs (fatty acid methyl esters) and lipase from porcine pancreas (type II) was purchased from Sigma-Aldrich Chemical Co Ltd. (Shanghai, China). Thin-layer chromatography plates (TLC; 10 × 20 cm; mean pore diameter 60 Å, average particle size 2–25 µm, thickness 500 µm, with dichlorofluorescein) were obtained from Shanghai Shangbang Decoration Materials Co., Ltd. (Shanghai, China). TAG standards, glyceryl trioleate (purity ≥ 99%), 1,3-myristin-2-olein (purity ≥ 99%), 1,3-olein-2-palmitin (purity ≥ 99%), 1(3)-palmitin-2-olein-3(1)-laurin (purity ≥ 99%) and 1(3),2-dioleoyl-3(1)-palmitoyl-sn-glycerols (purity ≥ 99%) were obtained from Larodan Fine Chemicals AB (Malmö, Sweden). Supercritical CO₂ (purity ≥ 99.999%) was bought from Wuxi Yuantong Company (Wuxi, China). N-hexane, ethanol, acetonitrile and ammonium formate were chromatographically pure and bought from J&K Scientific (Shanghai, China). Deionized water was utilized to prepare all solutions. All other solvents and reagents, such as methanol, chloroform, diethyl ether, potassium hydroxide, anhydrous sodium sulfate and acetic acid, were of chromatographic and analytical grade.