Identification and quantification of phosphatidylinositol in infant formulas by liquid chromatography–mass spectrometry

• A LC–MS method was developed to characterise phosphatidylinositols (PI) in infant formulas.
• A large variation in PI content was detected across 32 formula products.
• Species composition of PI also differs between formula brands.
• PI makes a significant contribution to total inositol, in some formula exceeding free inositol.

Using LC-LTQ-Orbitrap MS we were able to identify 10 major phosphatidylinositol (PI) species present in 32 infant formulas (IF) collected from Australia, Europe and the USA. Based on the species fingerprint, the 32 formulas can be classified into several distinct groups by PCA analysis; this grouping pattern reflects origin and the label information of the formulas. The total content of all PI species was determined by LC-Triple Quadrupole MS in negative MRM mode using external standard calibration. The content of PI showed large variation between formulas and was very high in certain cases, which is believed to be related to the use of soybean lecithin in these products. Our study indicates that the content and speciation of PIs have significant contribution to the total amount of inositol in all 32 products surveyed; this contribution may be important for the fine nutritional profile and biological functions of IF products.