Methods for detecting vitamin D metabolites by mass spectrometry
AssigneeQuest Diagnostics Investments Incorporated
InventorsNigel J. Clarke, Brett Holmquist, Gloria Kwang-Ja Lee, Richard E. Reitz
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Abstract
Provided are methods of detecting the presence or amount of a vitamin D metabolite in a sample using mass spectrometry. The methods generally directed to ionizing a vitamin D metabolite in a sample and detecting the amount of the ion to determine the presence or amount of the vitamin D metabolite in the sample. Also provided are methods to detect the presence or amount of two or more vitamin D metabolites in a single assay.
Claims4
A method for determining an amount of 25-hydroxyvitamin D3 or 25-hydroxyvitamin D2 in a sample by tandem mass spectrometry, the method comprising:
- (a) adding an internal standard to a first sample containing 25-hydroxyvitamin D3 or 25-hydroxyvitamin D2 to form a second sample;
- (b) purifying the second sample by liquid chromatography;
- (c) ionizing said 25-hydroxyvitamin D3 or 25-hydroxyvitamin D2 and the internal standard by atmospheric pressure chemical ionization (APCI) to form a precursor ion having a mass to charge ratio of 383.16±0.5 for 25-hydroxyvitamin D3 or 395.30±0.5 for 25-hydroxyvitamin D2;
- (d) generating one or more fragment ions of said precursor ion;
- and
- (e) determining an amount of the one or more of said fragment ions generated in step (d);
- and
- (f) determining an amount of 25-hydroxyvitamin D3 or 25-hydroxyvitamin D2 in said sample from the amount of the one or more of said fragment ions;
- and
- wherein the internal standard is a deuterated vitamin D metabolite.
Dependencies are inferred from the claim text.