Patent ID: 8852951
Filing Date: 2014-10-07
Classification: G01N,Y10T

Abstract:
1. A method for determining an amount of one or more dihydroxyvitamin D metabolites in a biological sample taken by tandem mass spectrometry; the method comprising: (i) generating at least one precursor ion respectively of the one or more dihydroxyvitamin D metabolites and of an internal standard by ionizing the one or more dihydroxyvitamin D metabolites and the internal standard with atmospheric pressure chemical ionization (APCI); (ii) generating one or more fragment ions of the precursor ion respectively of the one or more dihydroxyvitamin D metabolites and of the internal standard; and (iii) comparing amounts of one or more of the ions generated in step (i), (ii), or both, for the one or more dihydroxyvitamin D metabolites and the internal standard to determine the amount of the one or more dihydroxyvitamin D metabolites in the biological sample; wherein the one or more dihydroxyvitamin D metabolites are not subject to derivatization.