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While the biological function of the 3α epimer of 25-hydroxyvitamin D3 (25(OH)D3) remains unknown, its presence needs to be accurately captured and separated from the main 3β epimer, to avoid positive bias in vitamin D status analyses. Several recent LC-MS/MS assays for 25(OH)D3 successfully separate the 3α and 3β epimers by chromatography. Unfortunately, none of the existing LC-MS/MS assays, which...
Vitamin D measurements in biological fluids by mass spectrometry are challenging at very low concentration levels. As a result, chemical derivatization is often employed to enhance the ionization properties of low abundant vitamin D compounds. Cookson-type reagents such as 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) or similar derivatives work well but require careful, water-free experimental conditions,...
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