Fatemeh Mahmoodani
School of Chemical Sciences, University of Auckland, New Zealand
Title: Isolation and identification of vitamin D3 oxidation products in simulated whole milk powder by liquid chromatography mass spectrometry
Biography
Biography: Fatemeh Mahmoodani
Abstract
In a successful fortification program, the stability of micronutrients added to the food is one of the most important factors. The added vitamin D3 is known to sometimes decline during storage of fortified milk powders, and oxidation through fatty acid lipoxidatoin is suspected as the likely cause. The main objective of this study is to find a method to extract and to identify vitamin D3 oxidation products (VDOPs) in stored whole milk powder. Identification of VDOPs in natural foods is a challenge due to the low amount of their contents. An extraction method using a liquid-liquid extraction (LLE) followed by a solid phase extraction (SPE) was optimized to extract VDOPs. The bottleneck of the VDOPs’ identification could not be overcome without mass spectra prediction tools. The fragmentation trees and MSn spectral trees provided by Mass Frontier software gave reliable methods to identify vitamin D3 unknown compounds such as VDOPs. Methods based on high mass accuracy MS2 and MSn analysis have been developed for the identification of vitamin D3 and its oxidation products. The multi stage mass spectrometry (MSn) spectra can help to propose plausible schemes for unknown compounds and their fragmentations. This study was focused on identifying the fragmentation rules for some VDOPs by incorporating MS data with in silico calculated MS fragmentation pathways. Diels-Alder derivatization was used to enhance the sensitivity and selectivity for mass spectrometry data collection. Finally, the confirmed PTAD derivatised target compounds were separated and analyzed using ESI(+)-UHPLC-MS/MS in multiple reaction monitoring (MRM) mode in model samples.