Patent ID: 8729463

Claim:
A method of quantifying C3-epi-25-hydroxyvitamin D3 in a sample containing 25-hydroxyvitamin D3 and C3-epi-25-hydroxyvitamin D3, the method comprising: separating the 25-hydroxyvitamin D3 from the C3-epi-25-hydroxyvitamin D3, the separation comprising subjecting the sample to reverse-phase liquid chromatographic separation employing a convex solvent gradient curve and using a non-chiral reverse-phase column, wherein the column includes a stationary phase having a polar functional group, and detecting the C3-epi-25-hydroxyvitamin D3 using a mass spectrometry technique to determine at least one of a concentration and an amount of the C3-epi-25-hydroxyvitamin D3in the sample.