Quantification of cardiac troponin I in human plasma by immunoaffinity enrichment and targeted mass spectrometry

Published

September 30, 2016

Author(s)

Nicole A. Schneck, Karen W. Phinney, Sang Bok Lee, Mark S. Lowenthal

Abstract

Quantification of cardiac troponin I (cTnI), a protein biomarker used for diagnosing myocardial infarction, has been achieved in native patient plasma based on an immunoaffinity enrichment strategy and isotope dilution (ID) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The key steps in the workflow involved isolating cTnI from plasma using anti-cTnI antibody coupled to magnetic nanoparticles, followed by an enzymatic digestion with trypsin. Three tryptic peptides from cTnI were monitored and used for quantification by ID-LC-MS/MS via multiple reaction monitoring (MRM). Measurements were performed using a matrix-matched calibration system. NIST SRM 2921 Human Cardiac Troponin Complex acted as the calibrant and a full-length isotopically labeled protein analog of cTnI was used as an internal standard. The method was successfully demonstrated on five patient plasma samples, with cTnI concentrations measuring between 4.86 μg/L and 11.3 μg/L (signifying moderate myocardial infarctions). LC- MS/MS measurement precision was validated by three unique peptides from cTnI and two MRM transitions per peptide. Relative standard deviation (CV) from the five plasma samples was determined to be ≤14.3%. This study has demonstrated that quantification of cTnI in native plasma from myocardial infarction patients can be achieved based on an ID-LC-MS/MS method. The development of an ID-LC-MS/MS method for cTnI in plasma is a first step for future certification of matrix-based reference materials, which may be used to help harmonize discordant cTnI clinical assays.

Citation

Analytical and Bioanalytical Chemistry

Pub Type

Journals

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DOI Link

Keywords

antibody, magnetic particles, immunoaffinity, magnetic separation, LC-MS

Citation

Schneck, N. , Phinney, K. , Lee, S. and Lowenthal, M. (2016), Quantification of cardiac troponin I in human plasma by immunoaffinity enrichment and targeted mass spectrometry, Analytical and Bioanalytical Chemistry, [online], https://doi.org/10.1007/s00216-016-9948-3 (Accessed April 24, 2024)