US 12,253,532 B2
Mass spectrometric quantitation assay for metabolites of leflunomide
Karin O. Thomassian, Tujunga, CA (US)
Assigned to Quest Diagnostics Investments LLC, Secaucus, NJ (US)
Filed by Quest Diagnostics Investments LLC, Secaucus, NJ (US)
Filed on Dec. 18, 2023, as Appl. No. 18/543,588.
Application 18/543,588 is a continuation of application No. 17/745,551, filed on May 16, 2022, granted, now 11,879,900.
Application 17/745,551 is a continuation of application No. 16/827,539, filed on Mar. 23, 2020, granted, now 11,333,673.
Application 16/827,539 is a continuation of application No. 15/730,150, filed on Oct. 11, 2017, granted, now 10,598,676.
Application 15/730,150 is a continuation of application No. 14/930,025, filed on Nov. 2, 2015, granted, now 9,817,005.
Application 14/930,025 is a continuation of application No. 13/314,093, filed on Dec. 7, 2011, granted, now 9,177,766.
Claims priority of provisional application 61/428,551, filed on Dec. 30, 2010.
Prior Publication US 2024/0118294 A1, Apr. 11, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G01N 33/94 (2006.01); A61K 31/785 (2006.01); H01J 49/00 (2006.01)
CPC G01N 33/94 (2013.01) [A61K 31/785 (2013.01); G01N 33/9493 (2013.01); H01J 49/0036 (2013.01); G01N 2560/00 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for determining an amount of teriflunomide in a sample by mass spectrometry, said method comprising:
a. adding an internal standard to the sample;
b. subjecting the sample to solid phase extraction;
c. purifying the sample by high turbulence liquid chromatography;
d. ionizing the sample to produce one or more teriflunomide ions detectable by tandem mass spectrometry;
e. determining the amount of the one or more teriflunomide ions by tandem mass spectrometry, wherein the tandem mass spectrometry comprises fragmenting a precursor ion with a mass to charge ratio (m/z) of 271.3±0.50 into one or more fragment ions comprising ions with m/z of 162.1±0.50; and
f. using the amount of the one or more teriflunomide ions determined in step (e) to determine the amount of teriflunomide in the sample.