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Analysis of 25 underivatized amino acids in human plasma using ion‐pairing reversed‐phase liquid chromatography/time‐of‐flight mass spectrometry
Author(s) -
Armstrong Michael,
Jonscher Karen,
Reisdorph Nichole A.
Publication year - 2007
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3124
Subject(s) - chemistry , chromatography , amino acid , electrospray ionization , mass spectrometry , tandem mass spectrometry , isobaric labeling , dipeptide , calibration curve , electrospray , protein mass spectrometry , analytical chemistry (journal) , detection limit , biochemistry
Amino acids in biological fluids have previously been shown to be detectable using liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS) with perfluorinated acids as ion‐pairing agents. To date, these studies have used precursor mass, retention time and tandem mass spectrometry (MS/MS) to identify and quantify amino acids. While this is a potentially powerful technique, we sought to adapt the method to time‐of‐flight (TOF)MS. A new application of a recently described liquid chromatographic separation method was coupled with TOFMS to employ accurate mass for qualitative identification; resulting in additional qualitative data not available with standard single quadrupole data. In the current study, we evaluated 25 physiological amino acids and one dipeptide that are routinely quantified in human plasma. Accuracy and precision of the method was evaluated by spiking human plasma with a mix of the 25 amino acids; in addition, the inclusion of a cation‐exchange cleanup step was evaluated. The calibration curves were linear over a range from 1.56 to 400 µM. The dynamic range was found to be within physiological levels for all amino acids analyzed. Accuracy and precision for most of the amino acids was between 80–120% spike recovery and <10% relative standard deviation (RSD). The LC/MS technique described in this study relies on mass accuracy and is suitable for the quantitation of free amino acids in plasma. Copyright © 2007 John Wiley & Sons, Ltd.