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Efficient Separation and Analysis of Triacylglycerols: Quantitation of β-Palmitate (OPO) in Oils and Infant Formulas

Vyssotski, Mikhail, Bloor, Stephen J., Lagutin, Kirill, Wong, Herbert, Williams, D. Bradley G.
Journal of agricultural and food chemistry 2015 v.63 no.26 pp. 5985-5992
glycerol, infant formulas, isomers, light scattering, oils, quantitative analysis, reversed-phase high performance liquid chromatography, triacylglycerols
A high-efficiency, convenient, and reliable method for the separation of structurally similar triacylglycerols is detailed and applied in the quantitative analysis of 1,3-dioleoyl-2-palmitoylglycerol (OPO) in infant formulas and OPO oils. OPO is an important lipid component in “humanized” infant formula. A fast preparative isolation of an OPO-containing fraction from the crude complex mixture, by nonaqueous reversed phase HPLC, followed by Ag+-HPLC with detection at 205 nm allowed fine separation and detection of the desired fraction. OPO was quantitated independently of its regioisomer 1,2-dioleoyl-3-palmitoylglycerol (OOP) and isomers of stearoyl-linoleoyl-palmitoyl glycerol that might be present in infant formulas. For samples with low OPO content, an evaporative light-scattering detector (ELSD) was more preferable than UV detection, with a calculated LOD of 0.1 μg of OPO injected and LOQ of 0.3 μg. The method, which showed high reproducibility (RSD < 5%), was suitable for both high OPO content oils and low OPO products such as unenriched infant formula. A number of possible interference issues were considered and dealt with.