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Stereoselective analysis of herbicides by capillary electrophoresis using sulfobutyl ether β‐cyclodextrin as chiral selector
Author(s) -
Desiderio Claudia,
Polcaro Chiara M.,
Fanali Salvatore
Publication year - 1997
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/elps.1150180209
Subject(s) - capillary electrophoresis , cyclodextrin , chromatography , stereoselectivity , chemistry , ether , electrophoresis , organic chemistry , catalysis
Capillary zone electrophoresis has been used for the enantiomeric separation of several herbicides. Different β‐cyclodextrin (CD) derivatives have been investigated for chiral separations and among them the negatively charged sulfobutyl ether β‐cyclodextrin (SBE‐β‐CD) proved to be effective for the stereoselective resolutions of the investigated herbicides. The effect of CD concentration, buffer pH and organic modifier on effective mobilities, resolution and selectivity of the analytes have been studied. Addition of SBE‐β‐CD (5–50 mg/mL) to the buffer at pH 9 resulted in a general increase of migration times as well as resolution. A CD concentration as low as 5 mg/mL was effective to completely resolve napropamide and ethofumesate enantiomers. Buffer solutions containing 40 mg/mL of SBE‐β‐CD were chosen to study the effect of buffer pH (7, 8, and 9) on chiral separation of the herbicides. No great differences in resolution and effective mobilities have been found in the pH 7–9 range. The addition of different organic modifiers to the background electrolyte at pH 9, containing 20 mg/mL of SBE‐β‐CD, showed different effects. Methanol was the most effective in improving resolution but in some cases total loss in enantiomeric separation was observed. The qualitative analysis of an enantiomerically pure herbicide (flamprop isopropyl) commercial preparation is also shown.