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Determination of enantiomeric compositions of DOPA by tandem mass spectrometry using the kinetic method with fixed ligands
Author(s) -
Lee MinKwon,
Kumar Avvaru Praveen,
Jin Dongri,
Lee YongIll
Publication year - 2008
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.3437
Subject(s) - chemistry , enantiomer , electrospray ionization , analyte , mass spectrometry , ligand (biochemistry) , tandem mass spectrometry , ion , selectivity , chromatography , analytical chemistry (journal) , stereochemistry , organic chemistry , catalysis , biochemistry , receptor
A fixed ligand (FL) version of the kinetic method was applied to rapid, simple, and accurate chiral analysis of DOPA, which is an important drug used for treatment of Parkinson's disease. Singly charged clusters containing the transition metal ion Cu II , pyridyl ligands which serve as a fixed ligand, some amino acid as a reference, and the analyte DOPA were generated by electrospray ionization. The cluster ion of interest was mass‐selected, and the kinetics of its competitive unimolecular dissociations was investigated in an ion trap mass spectrometer. The chiral selectivity (R chiral ), the ratio of the two fragment ion abundances when the cluster contains one pure enantiomer of the analyte expressed relative to that for the other enantiomer, varies with fixed ligands, references, and transition metals. Chiral discrimination was optimized in 1,10‐phenanthroline as a FL, L‐Phe and L‐Pro as a reference, and Cu(II) as a central metal ion. Quantitative determinations of the enantiomeric composition of DOPA were achieved using two‐point calibration curves. The linear relationship between the logarithm of the fragment ion abundance ratio (ln R) and enantiomeric compositions (ee%) of the DOPA allows the determination of the chiral purity of enantiomeric mixtures. Copyright © 2008 John Wiley & Sons, Ltd.

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