The analysis of fat-soluble vitamins in dairy cow milk by high performance liquid chromatography-ion trap mass spectrometry

Fat-soluble vitamins A, D, E, and vitamin A precursor β-carotene are essential nutrients for the human body. The analysis of these compounds is difficult due to low levels (ppt - ppm), and physical and chemical similarity to other compounds present in foods. Traditionally, the determinative step uses high performance liquid chromatography (HPLC) coupled to either ultraviolet-visible (A, D, E and β-carotene) or fluorescence (A and E) detection. The work described in this thesis demonstrates that HPLC coupled with mass spectrometry (MS) is a viable alternative due to its superior selectivity and sensitivity, reducing the need for time-consuming sample preparation, and enabling the analysis of several vitamins in a single analytical method. High performance liquid chromatography-ion trap mass spectrometry (HPLC-MSn) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) methods were developed to measure the levels of vitamin D3 in fortified commercial cow’s milk (2 μg/100 ml), unfortified commercial and fresh cow’s milk (0.01-0.05 μg/100 ml). An additional solid phase extraction step enabled the lower levels (