Evaluation of dispersive liquid–liquid microextraction in the stereoselective determination of cetirizine following the fungal biotransformation of hydroxyzine and analysis by capillary electrophoresis

Abstract

We developed a capillary electrophoresis (CE) and dispersive liquid–liquid microextraction (DLLME) method to stereoselectively analyze hydroxyzine (HZ) and cetirizine (CTZ) in liquid culture media. The CE analyses were performed on an uncoated fused-silica capillary; 50mmolL−1 sodium borate buffer (pH 9.0) containing 0.8% (w/v) S-β-CD was used as the background electrolyte. The applied voltage and temperature were +6kV and 15°C, respectively, and the UV detector was set to 214nm. Chloroform (300µL) and ethanol (400µL) were used as the extraction and disperser solvents, respectively, for the DLLME. Following the formation of a cloudy solution, the samples were subjected to vortex agitation at 2000rpm for 30s and to centrifugation at 3000rpm for 5min. The recoveries ranged from 87.4 to 91.7%. The method was linear over a concentration range of 250–12,500ngmL−1 for each HZ enantiomer (r>0.998) and 125–6250ngmL−1 for each CTZ enantiomer (r>0.998). The limits of quantification were 125 and 250ngmL−1 for CTZ and HZ, respectively. Among the six fungi studied, three species were able to convert HZ to CTZ enantioselectively, particularly the fungus Cunninghamella elegans ATCC 10028B, which converted 19% of (S)-HZ to (S)-CTZ with 65% enantiomeric excess.