| A sensitive, high-throughput method is described for the analysis of 25-OH vitamin D2 (25-OH D2) and 25-OH vitamin D3 (25-OH D3) in serum by LC-MS/MS. Protein precipitation eliminates proteins and disrupts serum protein binding of 25-OH D2 and 25-OH D3, and chromatographic separation is carried out in less than 1 minute using a Kinetex 2.6 µm C18 core-shell column, with total chromatographic cycle time of 6 minutes. This method provides LOD of 1 and 2 ng/mL, respectively, for 25-OH D3 and 25-OH D2 with CV of 4-7% over the linear range 0.5 to >500 ng/mL, and speeds the diagnosis of potential vitamin D deficiencies. |
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