Simultaneous separation of the enantiomers of six anticoagulant rodenticides using chiral supercritical fluid chromatography-mass spectrometry.

The simultaneous separation of the enantiomers of six anticoagulant rodenticides, derived from 4-hydroxycoumarin, has been studied in this work. Ten different stationary phases (zwitterionic, Pirkle-type, polysaccharides and macrocyclic antibiotics derivatives) were evaluated by using supercritical fluid chromatography coupled to two different detectors (circular dichroism and mass spectrometry-single quadrupole). The effect of the type of organic modifier and temperature on the chiral separation was investigated, and the best results were obtained with the column Regis S,S-Whelk-O1 at 25 °C when using a gradient elution program with methanol as organic modifier. Considering detection, the highest sensitivity was obtained with the single quadrupole mass spectrometry detector. Under these conditions, eighteen stereoisomers were baseline resolved within 18 min. It should be also mentioned that the columns Chiralpak AS-H, Lux Cellulose-2, Chiralpak AD and Chiralpak Zwix (+) provided also good results for the enantiomeric separation of some individual compounds.