Determination of 1,3-olein-2-palmitin (OPO) content in infant formula by liquid chromatography coupled mass spectrometry LC-MS/MS

1,3-olein-2-palmitin (OPO - Sn2-palmitate) is a triacylglycerol found in breast milk that helps absorb nutrients in the infant’s intestine. Because of its beneficial effect on the infant's health improvement, OPO has been added by manufacturers to infant and infant formula. OPO content becomes an important criterion for milk quality. Therefore, it is necessary to develop a method to analyze OPO in formula milk products, contributing to assessing the quality of formula products being circulated in the market. In this study, OPO was determined by liquid chromatography-mass spectrometry (LC-MS/MS) using an Agilent Poroshell 120 EC-C18 chromatographic column, with an ESI (+) positive electron spray ionization source and multiple reaction monitoring (MRM) mode. The validity of the method was confirmed according to the guidelines of the Association of Official Analytical Chemists (AOAC). The results showed that the method has good specificity, the linearity range from 3.0 to 300 µg/kg, the detection limit of 1.0 µg/kg, the quantification limit of 3.0 µg/kg; precision and accuracy with relative standard deviation (RSD) less than 12% and recoveries ranging from 89.6 to 112%, meeting AOAC requirements. The method was used to analyze the OPO content in 17 infant formula products in Hanoi.