Patent ID: 9535077
Date: 2017-01-03
CPC Classifications: G01N,H01J,Y10T

Claim:
1. A method for determining an amount of one or more vitamin D metabolites in a sample by mass spectrometry, the method comprising: (i) subjecting the sample and an internal standard to a Cookson-type derivatizing reagent under conditions sufficient to generate one or more Cookson-type vitamin D metabolite derivatives and one or more Cookson-type internal standard derivatives, wherein the internal standard comprises at least one of 25OHD (ii) subjecting the one or more Cookson-type vitamin D metabolite derivatives and the one or more Cookson-type internal standard derivatives to turbulent flow liquid chromatography (TFLC); (iii) ionizing the one or more Cookson-type vitamin D metabolite derivatives and the one or more Cookson-type internal standard derivative to generate respectively one or more Cookson-type vitamin D metabolite derivative ions and one or more Cookson-type internal standard derivative ions detectable by mass spectrometry; (iv) determining an amount of the one or more of the Cookson-type vitamin D metabolite derivative ions and an amount of the one or more Cookson-type internal standard derivative ions by mass spectrometry; and (v) relating the amounts of the Cookson-type vitamin D metabolite derivative ions and the one or more Cookson-type internal standard derivative ions determined in (iv) to the amount of a vitamin D metabolite in the sample.