17th International Mass Spectrometry Conference :: Prague, 2006
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|Session:||Ion Mobility Mass Spectrometry|
|Presentation date:||Mon, Aug 28, 2006|
|Presentation time:||14:30 – 16:00|
Axel Mie1, Magnus Jornten-Karlsson2, Bengt-Olof Axelsson2, Andrew Ray3, Curt T. Reimann11 Lund University, Lund, Sweden
Correspondence address: Axel Mie, Lund University, Department of Analytical Chemistry, Box 124, Lund, 22100 Sweden.
Keywords: Chiral Recognition; Cluster, Ionic; Enantiomers; Mass Spectrometry, Ion Mobility.
Novel aspect: Enantiomer separation in FAIMS.
We present a method for separating and quantifying enantiomers with field-asymmetric ion mobility spectrometry (FAIMS), using electrospray ionisation (ESI), FAIMS separation and mass spectrometric (MS) detection. Enantiomers are only separable in situations offering suitable asymmetric chemical interactions; neither FAIMS nor ion drift mobility techniques normally present such asymmetries. To a sample of a mixture of enantiomers, we add an enantiopure chiral reference compound, in order to create cluster ions in which the chiral reference compound presents a local asymmetric (chiral) environment. These cluster ions can be regarded as diastereomers, and are thus in principle separable with ion mobility spectrometric techniques.
For example, pairs of amino acid enantiomers in a sample were separated in FAIMS by adding an enantiopure reference amino acid and a divalent metal ion to the sample, in order to create complex ions in the ionisation process, each consisting of one molecule of the analyte amino acid of interest, two molecules of reference compound, and one divalent metal ion: [MII(D/L-analyte)(L-reference)2-H]+.
The separation in FAIMS takes a few hundred milliseconds only. The presented method is thus a very fast method for separation of enantiomers, as the timescale for separation in gas chromatography, liquid chromatography or capillary electrophoresis normally is minutes. The degree of separation was in some cases excellent.
By coupling the FAIMS interface to a mass spectrometer, the presented separation method opens new possibilities for sensitive analysis of one enantiomer in the presence of the other enantiomer; preliminary results show that contamination of one (desired) enantiomer with 0.1% of the other (undesired) enantiomer can be detected. This makes the presented method valuable for applications such as quality control of enantiopure drugs.