Development and Evaluation of an Isotope Dilution LC/MS Method for the Determination of Total Homocysteine in Human Plasma

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• 作者：Bryant C. Nelson ; Christine M. Pfeiffer ; Lorna T. Sniegoski ; and Mary B. Satterfield
• 刊名：Analytical Chemistry
• 出版年：2003
• 出版时间：February 15, 2003
• 年：2003
• 卷：75
• 期：4
• 页码：775 - 784
• 全文大小：149K
• 年卷期：v.75,no.4(February 15, 2003)
• ISSN：1520-6882

文摘

Elevated plasma homocysteine has been identified as astrong and independent risk factor for cardiovasculardiseases, and recently, it has been associated with thedevelopment of dementia in older adults. Selected ion-monitoring isotope-dilution LC/MS (electrospray) hasbeen developed and evaluated as a reference method forthe accurate determination of total homocysteine in human plasma. Homocysteine is quantitatively isolated fromplasma via the use of anion-exchange resins and thendetected and quantified in stabilized plasma extracts withselected ion-monitoring LC/MS. This method is shown tobe highly comparable to LC/MS/MS determinations interms of its analytical accuracy and precision, yet thisalternative measurement approach does not necessitatethe enhanced instrumentation or added expense requiredof tandem MS/MS determinations. LC/MS detection ofhomocysteine was linear (standard error of the estimatefor the regression line was 0.0323) over 3 orders ofmagnitude, and the calculated limits of detection andquantification were 0.06 tities/mgr.gif">mol/L (0.12 ng on column) and0.6 tities/mgr.gif">mol/L (1.2 ng on column), respectively. Independent calibration curves showed excellent linearity (r² tities/ge.gif">0.996) between 0 and 25 tities/mgr.gif">mol/L homocysteine over a3-day period. The accuracy and precision of total homocysteine measurements for patient samples and qualitycontrol pools using LC/MS were compared to total homocysteine measurements using LC/MS/MS, GC/MS, FPIA,and LC-FD. LC/MS performed well in relation to the otherhomocysteine methods in terms of its capability to accurately quantify plasma homocysteine over the normalrange (5-15 tities/mgr.gif">mol/L).