Determination of sialic acids in infant formula by liquid chromatography tandem mass spectrometry

A liquid chromatographic/tandem mass spectrometric method using pneumatically assisted electrospray ionization (LC-ESI-MS/MS) was developed for determination of N-acetylneuramic acid and N-glycolylneuramic acid in infant formula Reconstituted samples were hydrolysed in dilute sulfuric acid and deproteinized with acetonitrile The extract was analysed directly without further clean-up by hydrophilic interaction chromatography The substances were detected in negative ion mode and matrix matched standards were used for calibration The relative intra-laboratory reproducibility standard deviation was better than 6% for both substances An R(2) of 0 985 was obtained by comparison with a classical colorimetric assay based on reaction with resorcinol The developed method is expected to be applied for accurate routine analysis of infant formulas Copyright (C) 2010 John Wiley & Sons, Ltd