Patent ID: 8257977
Filing Date: 2012-09-04
Classification: G01N,Y10T

Abstract:
1. A method for determining an amount of an analyte selected from a secosteroid metabolite and a steroid metabolite in a test sample, the method comprising: (a) providing a set of calibrator samples, each calibrator sample comprising a different amount of a first isotopically-labeled standard in a biological matrix; (b) providing to each calibrator sample a selected constant amount of a second isotopically labeled standard, the first and second isotopically labeled standards having distinct isotope content, and wherein the first and second isotopically labeled standards are isotopically-labeled analyte derivatives; (c) subjecting the calibrator samples comprising the first and second isotopically-labeled standards to mass spectrometry to determine signal intensities corresponding to the first and second isotopically-labeled standards; (d) generating a calibration curve based on ratios of the determined signal intensities of the first and second isotopically-labeled standards as a function of the amount of the first isotopically-labeled standard in the calibrator samples; (e) contacting a test sample with the selected constant amount of the second isotopically-labeled standard; (f) subjecting the test sample comprising the second isotopically-labeled standard to mass spectrometry to determine signal intensities corresponding to the second isotopically labeled standard and the analyte; and (g) using the calibration curve and the determined signal intensities corresponding to the second isotopically labeled standard and the analyte to determine the amount of the analyte in the test sample.