Simultaneous chiral separation of triadimefon and triadimenol by sulfated β-cyclodextrin-mediated capillary electrophoresis

Abstract

Enantiomeric separation of two triazole fungicides, triadimefon, was investigated in sulfated β-cyclodextrin (sulfated β-CD)-mediated capillary electrophoresis (CE) systems. It was found that, at pH 2-4, sulfated β-CD exhibited strong chiral recognition towards both triadimefon and triadimenol. The enantiorecognition was believed to result from the multiple interactions between sulfated β-CD and the analytes, which included inclusion effect, electrostatic interaction, and hydrogen bonding. Under optimal conditions (phosphate buffer with 2% sulfated β-CD, pH 2.5), simultaneous resolution of all chiral isomers of triadimefon and triadimenol was achieved in less than half an hour. In conjunction with solvent extraction and subsequent enrichment by solid-phase extraction (SPE), this new enantioseparation method was applied successfully in the study of stereoselectivity associated with the biotransformation of triadimefon to triadimenol by soil microorganisms. The present methodology was superior to the commonly adopted chiral gas chromatography (GO) approach in that a very mild procedure was involved from sample extraction to the ultimate chiral separation. Thus, the disturbance of the enantiomeric distribution patterns of the original soil samples by heat stress was an unlikely scenario. Furthermore, it was discovered that, owing to the unique selectivity of the present separation strategy, there was virtually no interference from the soil matrix, which led to improvements in both sensitivity and selectivity in real sample determination.