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Modelling, optimisation and control of selectivity in the separation of aromatic bases by electrokinetic chromatography using a neutral cyclodextrin as a pseudostationary phase
Author(s) -
Zakaria Philip,
Macka Miroslav,
Haddad Paul R.
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200206)23:12<1844::aid-elps1844>3.0.co;2-9
Subject(s) - electrokinetic phenomena , cyclodextrin , selectivity , chemistry , chromatography , micellar electrokinetic chromatography , phase (matter) , electrophoresis , organic chemistry , catalysis
A simple mathematical model describing the separation of a series of aromatic bases by electrokinetic chromatography using β‐cyclodextrin (β‐CD) as a pseudostationary phase is described. The model takes into account changes in electrolyte pH and the different formation constants between the neutral and charged forms of the analytes with the CD. Constants in the model were obtained within the two‐dimensional experimental space defined by pH and [β‐CD] with nonlinear regression using only five experimental points. These constants agreed with expected trends in analyte‐CD interactions and predicted much higher formation constants for the neutral analyte‐CD complex than for the charged analyte‐CD complex. Correlation between predicted and observed mobilities using additional 20 points within the experimental space gave r 2 = 0.995. Optimisation of the pH and [β‐CD] was performed using both the normalised resolution product and minimum resolution product criteria and provided two optimum separations which exhibited different selectivities. Differences between predicted and observed migration times at these optima were less than 2.5 and 5% for the normalised resolution product and the minimum resolution criteria, respectively. In both cases the correct migration order was predicted. The model was also applied successfully to the optimisation of conditions for the separation of a specific mixture of analytes or for conditions under which particular analytes migrated in a desired order.