Identification and Structural Elucidation of Vitamin D3 Metabolites in Human Urine Using LC-MS-MS

Accurate Clinical Detection of Vitamin D by Mass Spectrometry: A Review

Vitamin D deficiency is thought to be associated with a wide range of diseases, including diabetes, cancer, depression, neurodegenerative diseases, and cardiovascular and cerebrovascular diseases. This vitamin D deficiency is a global epidemic affecting both developing and developed countries and therefore qualitative and quantitative analysis of vitamin D in a clinical context is essential. Mass spectrometry has played an increasingly important role in the clinical analysis of vitamin D because of its accuracy, sensitivity, specificity, and the ability to detect multiple substances at the same time. Despite their many advantages, mass spectrometry-based methods are not without analytical challenges. Front-end and back-end challenges such as protein precipitation, analyte extraction, derivatization, mass spectrometer functionality, must be carefully considered to provide accurate and robust analysis of vitamin D through a well-designed approach with continuous control by internal and external quality control. Therefore, the aim of this review is to provide a comprehensive overview of the development of mass spectrometry methods for vitamin D accurate analysis, including emphasis on status markers, deleterious effects of biological matrices, derivatization reactions, effects of ionization sources, contribution of epimers, standardization of assays between laboratories.

Sample preparation techniques for extraction of vitamin D metabolites from non-conventional biological sample matrices prior to LC-MS/MS analysis

The determination of vitamin D metabolites as status marker or for diagnostic purposes is almost entirely conducted from blood serum or plasma. Other biological matrices, however, have also interested researchers, for two main reasons: (1) alternative matrices may allow non-invasive sampling, permit easier sample transfer and require less demanding storage conditions; and (2) the levels of vitamin D metabolites in other body compartments may further aid the understanding of vitamin D metabolism and function. Thus, the development of reliable and efficient sample preparation protocols for sample matrices other than serum/plasma, which will remove potential interferences and selectively extract the targeted metabolites, is of great importance. This review summarizes sample preparation methods for measurement of vitamin D metabolites using liquid chromatography-(tandem)mass spectrometry in more than ten different human tissues, including hair, saliva, adipose tissue, brain and others.

Overview of extraction methods for analysis of vitamin D and its metabolites in biological samples

In the last decade the scientific and medical community was confronted with a renewed interest in vitamin D and its metabolites, interest prompted by new discoveries regarding the association between members of the vitamin D family and a great number of physiological functions and pathological states. An impressive number of research projects have helped clear the path towards a better understanding of the functions of vitamin D and have resulted in the development of numerous methods of analysis. This review focuses on the various extraction methods used for analysis of vitamin D in research or clinical settings. Two main extractive methods are usually employed: liquid–liquid extraction and solid-phase extraction. Some methods use no extraction step and direct analysis is performed at the cost of significantly increased matrix interference. On the other hand, other methods use combined extraction techniques, and even additional derivatization steps in order to increase the sensitivity and accuracy of the analysis. The method of choice ultimately depends on the research question and the purpose of the study.