Determination of Total Plasma Homocysteine by Stable Isotope Dilution LC-MS and LC-MS/MS

Mary B. Satterfield1, Christine M. Pfeiffer2, Lorna T. Sniegoski1 and Bryant C. Nelson1 

1Analytical Chemistry Division, CSTL, National Institute of Standards and Technology,  Gaithersburg, MD 20899, USA
2 Division of Laboratory Sciences, Centers for Disease Control and Prevention,  Atlanta, GA 30341-3724, USA


Abstract An increased level of the amino acid, homocysteine (Hcy), in the circulating blood system of humans has been strongly correlated with an enhanced risk of coronary artery disease, cerebrovascular disease and peripheral vascular disease. Many different analytical methods including liquid chromatography (LC), fluorescence polarization immunoassay (FPIA), gas chromatography directly combined with mass spectrometry (GC/MS), and most recently, LC directly combined with isotope dilution tandem mass spectrometry (LC-MS/MS) have been developed for the determination of Hcy in plasma. But as of yet, no single method has been shown by interlaboratory comparisons to be selective and accurate enough to yield reproducible values in different laboratories. There exists a critical need for Hcy standard reference method(s) and the Analytical Chemistry Division has developed LC-MS and LC-MS/MS methods in an attempt to address this need. Each method has been evaluated in terms of analytical precision, recovery, accuracy, reproducibility, stability, etc., for the determination of Hcy in human plasma. Preliminary analysis and comparison of the data suggest that both methods could function as Hcy reference methods.

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