Chiral separation of conazole pesticides using supercritical fluid chromatography

Supercritical fluid chromatographic methods for enantiomer separation of six conazole-type antifungal pesticides (bromuconazole, cyproconazole, prothioconazole, tebuconazole, ipconazole, triticonazole) are presented in this work. Screening tests on six different chiral analytical columns (Chiralpak IA, Chiralpak IB, Chiralpak IC, Chiralpak AS, Chiracel OJ and Kromasil Cellucoat) were carried out using methanol as organic modifier. Cellulose-based stationary phases were found to be better for separation of each tested conazole, than the amylose-based columns. The influence of the most commonly used co-solvents (methanol, ethanol and 2-propanol) on the separation was also studied on selected columns. Suitable analytical methods were found for enantiomer separations for all studied conazoles; moreover, the methods are good starting points to semi-preparative separation. The importance of sample solvent selection in the semi-preparative separation of triticonazole isomers was proved. Acetonitrile as sample solvent resulted in a narrow, nice peaks compared to those obtained with methanol or dichloromethane. Twenty milligrams of each enantiomer of triticonazole was collected for ecotoxicity testing using the analytical size column.