ESI/TOF-MS Detection for Microseparation Techniques

The choice of electrospray ionisation/time-of-flight mass spectrometry (ESI/TOF-MS) as mass analyser for combination with microseparation techniques, such as µLC, CE and CEC, may be recommended due to the features that present-day TOF-MS instruments have to offer. Advanced digital electronics, which ensure a fast and accurate data handling over a more or less 'unlimited' mass range, make these mass spectrometers the instruments of choice to sensitively cope with low flow rates, high-speed analyses and often very narrow bandwidths without risking the loss of valuable information. Recent achievements in interfacing microseparation techniques to ESI/TOF-MS will be presented and discussed

Separability of racemates in chiral chromatography: attempts to explain chiral recognition through structure-retention relationships.

With the studies described in this thesis, we intended to make the retention and/or separation behaviour of pharmaceutically relevant racemic compounds on different chiral stationary phases more understandable, if not more predictable. Zie:Summary

Impact of substituents on the enantioseparation of racemic 2-amidotetralins on polysaccharide stationary phases .1. Chiralcel OD

The direct enantiomeric separation of 32 racemic 2-amidotetralins on the commercially available tris-(3,5-dimethylphenylcarbamate) derivative of cellulose, coated on silica gel (Chiralcel OD), is presented. To date, the selection of a column for the chiral separation of a racemic mixture is done empirically. Studying the impact of small changes in the chemical structure of a series of amidotetralins on the separation behavior may help to give an insight in the chiral recognition mechanism. The amidotetralins differed structurally in three of their substituents, which were never directly located on the chiral carbon atom. The enantiomers of 24 out of 32 amidotetralins could be resolved with a resolution >1.5. Hydrogen bonding and pi-pi interactions are supposed to be the major analyte-chiral stationary phase (CSP) interactions. However, the spatial arrangement of the enantiomers may play an important role too. Increasing the bulkiness of the acyl substituent led to an increase in the resolution (R(s)), whereas a more bulky substituent on the aromatic ring resulted in a very low resolution. The introduction of a chlorine atom into the acyl substituent additionally increased the resolving power. (C) 1997 Wiley-Liss, Inc

Preparation of (S)-(+)- and (R)-(-)-8-trifluoromethanesulfonyloxymianserin

8-Trifluoromethanesulfonyloxymianserin (3) was synthesized. Its enantiomers were separated by means of HPLC using a chiral stationary phase in the semipreparative mode (100 mg scale) in greater than or equal to 99% optical purity. Reduction of the enantiomers of 3 under catalytic hydrogenation conditions gave the mianserin enantiomers in high purity. The absolute configuration of the enantiomers of 3 were assigned by comparing their respective optical rotations with those of the mianserin enantiomers