CHIRAL CONVENTIONAL VS. MICRO HPLC
681
phase flow with smaller particles.21 Nonetheless, due to insuffi-
cient baseline separations on the capillary column, conclusions
about peak efficiency cannot be drawn.
conventional HPLC and capillary-LC under normal phase chro-
matographic conditions. Baseline separation was achieved
for 1-acenaphthenol, 4-bromogluthethimide, carprofen, celiprolol,
1-(2-chlorophenyl)ethanol, cizolirtine carbinol, flavanone,
6-hydroxyflavanone, 4-hydroxy-3-methoxymandelic acid, 1-indanol,
miconazole, pentobarbital, 1-phenyl-2-propanol, and tebuconazole
on the conventional column and for aminoglutethimide,
naftopidil, and thalidomide on the capillary counterpart.
Parameters such as the content and conformation of the CS
in both column formats need to be considered. Further
studies on different CSs/solid support combinations is recom-
mended so that conclusions can be drawn regarding columns
performance. The complexity of the chiral recognition
mechanisms could be simplified using miniaturized models
to study the mechanism on the molecular level and explore
the possibilities of scaling up the results.
It is evident that direct method transfer between the con-
ventional column Chiralpak ID and its antipode Chiralpak
ID-3 was not applicable in this study. However, this sheds
light on the potential use of miniaturized techniques to study
the interactions between the CS and the analytes from a ther-
modynamics point of view and trying to maintain the interac-
tions on the larger scale. The use of miniaturized techniques
might help in better understanding the CS-analyte interaction
on the molecular level when the chiral selector is firmly
immobilized on a solid support.
Miniaturization of Chiral Separations: A Future Perspective
Downscaling of the chromatographic techniques from con-
ventional to micro to nano- HPLC is considered a green anal-
ysis approach. Miniaturization of instrumentation results in
small solvent consumption and reduced waste production
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a
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and capillary electrophoresis (CE). Baseline separation of
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24
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1
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CONCLUSIONS
This study demonstrates that the prediction of column per-
formance when miniaturized cannot be based on the
performance of its conventional antipode. Amylose tris-(3-
chlorophenylcarbamate) immobilized on silica gel was
investigated for the enantioselective separation of a set of 13
different classes of racemic pharmaceuticals using
1
Chirality DOI 10.1002/chir