The establishment of EVISA is funded by the EU through
the Fifth Framework Programme (G7RT- CT- 2002- 05112).
Supporters of EVISA includes:
chiral HPLC column
Chiral HPLC columns are made by immobilising single enantiomers onto
the stationary phase. Resolution relies on the formation of transient
diastereoisomers on the surface of the column packing. The compound
which forms the most stable diastereoisomer will be most retained,
whereas the opposite enantiomer will form a less stable diastereoisomer
and will elute first.
The forces that lead to this interaction are very weak and require
careful optimisation by adjustment of the mobile phase and temperature
to maximise selectivity. Typically a free energy of interaction
difference of only 0.03 kJ/mol between the enantiomers and the
stationary phase will lead to resolution.
The effect of temperature is important in chiral HPLC. Lower
temperature will increase chiral recognition, but as it alters the
kinetics of mass transfer, it may actually make the chromatography
worse by broadening peaks. There is often an optimum temperature for a
separation and knowledge of this gives the analyst another factor to
exploit in the method development process
The type of column used for separating a class of enantiomer is often
very specific, this combined with the high cost of chiral columns,
makes the choice of which column to use very critical.