The determination of vitamin D3 in bovine milk by liquid chromatography mass spectrometry

A renewed international Interest in vitamin D status has revealed significant deficiencies in several populations including Australia Vitamin D exists in two forms cholcalciferol (D-3) and ergocalciferol (D-2) The main source of vitamin D-3 is from exposure of 7-dehydrocholesterol present in the skin to UV irradiation However there is an absolute requirement for vitamin D through proper dietary intake if humans live in the absence of sunlight or exclusively indoors Bovine milk is considered to be a good dietary source of vitamin D-3 even though the levels are quite low This paper describes robust methods using liquid chromatography-linear ion trap mass spectrometry (LC-MSn) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure the levels of vitamin D-3 in fresh bovine milk (0 05 mu g/ 100 ml) commercial (natural and fortified) milk samples (0 01-2 mu g/100 ml) and a dairy based infant formula (8 mu g/100 g) without the need for extensive clean-up procedures The limits of quantification (LOQ) are 0 01 mu g/100 ml and 0 02 mu g/100 ml for LC-MSn and LC-MS/MS respectively Recoveries of vitamin D-3 added to the samples prior to saponification were satisfactory (range 60-90%) 25-Hydroxyvitamin D-3 was not present in any of the samples analysed (LOQ = 001 mu g/100 ml recovery range 30-40%) Crown Copyright (C) 2010 Published by Elsevier Ltd All rights reserved