A novel simultaneous quantification method for fat-soluble vitamins using liquid chromatography-tandem mass spectrometry for clinical applications

The accurate and precise quantification of fat-soluble vitamins (FSVs), specifically vitamins A, D and E, has proved to be a challenge for clinical laboratories. This challenge is partially the result of the nature of FSV molecules and the limitations in techniques commonly used in their analysis. Consequently, there is a variation in the results obtained through different techniques or by different clinical laboratories. As a result, it has been difficult to reach agreement on the recommended levels or reference intervals of these vitamins. The current project encompassed the development of a state-of-the-art analytical method for the analysis of vitamins A (retinol), D (25-hydroxyvitamin D [25-OHD]) and E (α-tocopherol) in blood using liquid chromatography-tandem mass spectrometry (LC-MS/MS), which is a highly sensitive and specific quantification technique. Four studies were then performed to explore several scientific knowledge gaps related to vitamin measurement using the developed FSV quantification methods.<br><br>The Current translational clinical research introduced novel and precise simultaneous measurement methods for blood FSV analytes, which were applicability to clinical sampling trials. This thesis also provides the first study exploring the stability FSVs simultaneously in routine sample spectrum utilising a precise LC-MS/MS method. In addition, stability of each analytes is justified based on calculation of the acceptable clinical limits, which reflect biological variation as well as method imprecision. This project also highlighted problematic issue related to trueness and reliable traceability of commercial calibrators to high order references and that interrupts effort of method harmonisation and patient result comparability. Furthermore, the current thesis provides with first study validated the measurement of 25-OHD3 and retinol in UCB diluted plasma. Lastly, this thesis reports the first study exploring status of five FSV analytes in two Australian populations at different latitudes using simultaneous measurement LC-MS/MS method. Furthermore, this is the first work examined the correlation between the blood FSV levels in two Australian populations.