The determination of vitamin D₃ in bovine milk by liquid chromatography mass spectrometry
2011
Trenerry, V Craige | Plozza, Tim | Caridi, Domenico | Murphy, Stacey
A renewed international interest in vitamin D status has revealed significant deficiencies in several populations, including Australia. Vitamin D exists in two forms, cholcalciferol (D₃) and ergocalciferol (D₂). The main source of vitamin D₃ 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 D₃, even though the levels are quite low. This paper describes robust methods using liquid chromatography–linear ion trap mass spectrometry (LC–MSâ¿) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) to measure the levels of vitamin D₃ in fresh bovine milk (0.05μg/100ml), commercial (natural and fortified) milk samples (0.01–2μg/100ml) and a dairy based infant formula (8μg/100g), without the need for extensive clean-up procedures. The limits of quantification (LOQ) are 0.01μg/100ml and 0.02μg/100ml for LC–MSâ¿ and LC–MS/MS, respectively. Recoveries of vitamin D₃ added to the samples prior to saponification were satisfactory (range 60–90%). 25-Hydroxyvitamin D₃ was not present in any of the samples analysed (LOQ=0.01μg/100ml, recovery range 30–40%).
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