Biomedical Engineering Reference
In-Depth Information
5.6.3 C
APILLARY
E
LECTROPHORESIS
This relatively new method of enantioseparation involves the use of capillary electromigration
techniques. In common with chiral GC and HPLC the origin of the enantioseparation lies in the
noncovalent intermolecular interactions between the analyte and the chiral selector and is not based
on electrophoretic mobility, as enantiomers possess the same charge densities. Capillary electrophoresis
is usually carried out with bare silica capillaries. For this reason the chiral selector is added to the
electrolyte in order to form diastereomeric complexes with the analyte thereby effecting chiral
discrimination. In common with HPLC a number of chiral selectors have been used to effect enanti-
oseparation such as cyclodextrins, polysaccharides, macrocyclic antibiotics, and proteins.
5.6.4 M
ASS
S
PECTROMETRY
A newly emerging technology is the use of mass spectroscopy for the rapid analysis of chiral drugs.
Mass spectroscopy methods are generally based on the formation of diastereomeric adducts, which
can be mass resolved via different techniques.
5.7 CONCLUDINGREMARKS
Chiral drugs have been in use in medicine throughout history. However, it is only in recent times
that the importance of chirality in drug design and development has come to light. The tragic case
of thalidomide highlighted the importance of testing the individual enantiomers of chiral drugs.
This has spurred on the development of a range of methods for obtaining individual enantiomers of
chiral drugs and for assessing their purity. There is no doubt that the proportion of drugs marketed
as individual enantiomers will continue to rise as technological advances emerge to produce single
enantiomers in bulk quantities.
FURTHER READINGS
Aitken, R.A. and Kilenyi, S.N. 1994.
Asymmetric Synthesis
, 1st edn. London: Chapman & Hall.
Eliel, E.L., Wilen, S.H., and Doyle, M.P. 2001.
Basic Organic Stereochemistry
. New York: John Wiley & Sons,
Inc.
Francotte, E. and Linder, W. 2006.
Chirality in Drug Research
. Germany: Wiley-VCH.
Sheldon, R.A. 1993.
Chirotechnology, Industrial Synthesis of Optically Active Compounds
. New York: Marcel
Decker.
