Mass Spectrometry of Lipid Vitamins
The deficiency of lipid vitamins is a worldwide issue. Deficiency in these vitamins has been associated with multiple diseases. Thus, there is an increasing interest in the assessment of the status of vitamins A, D, E and K. Usually, serum or plasma levels of one or more vitamin species or metabolites thereof are determined when assessing vitamin status. Lipid vitamins have historically been determined by either immunoassays, or ultraviolet, fluorescence and electrochemical detection. Mass spectrometry combines sensitivity, specificity with structural elucidation and is therefore gaining popularity and becoming the gold standard for analysis of vitamin lipids. This chapter reviews the analysis of lipid vitamins in serum or plasma by liquid chromatography or gas chromatography coupled to mass spectrometry. Sample preparation, the chromatographic setup, ionisation, derivatisation techniques, and common fragments formed during tandem mass spectrometry, are reviewed for each lipid vitamin.