Determination of (+/−) Elution Orders of Chiral Organochlorines by Liquid Chromatography with a Chiral Detector and by Enantioselective Gas Chromatography

Abstract

Abstract Enantioselective gas chromatography (GC) with 5 modified cyclodextrins was applied to chiral organochlorines. A prerequisite for determining GC elution orders of enantiomers is the availability of enantioenriched standard solutions. In addition to compounds reported before (e.g., α-HCH, PCB 174, oxychlordane), we determined the sign of optical rotation of enantioenriched solutions of e-aeee-pentachlorocyclohexene-1 (β-PCCH), perdeuterated α-HCH (α-PDHCH), perdeuterated β-PCCH, and the persistent compound of technical toxaphene—2-exo,3-endo,5-exo,9,9,10,10-heptachlorobornane (B7-1453)—by liquid chromatography (LC) with a chiral detector. An enantioenriched solution of (β-PCCH was obtained by enantioselective degradation of α-HCH with (-)-brucine. In addition to forming an enantiomeric excess of (-)-α- HCH, we formed enantioenriched (+)-(α-PCCH. In a similar study, α-PDHCH showed the same behavior with respect to enantioselectivity. Dextrorotation of an enantioenriched solution of B7-1453 was also confirmed by LC with a chiral detector. Enantioseparation of chiral organochlorines on 5 chiral stationary phases resulted in several reversed elution orders. These results indicate that a careful check of elution orders of organochlorine enantiomers is necessary prior to comparison of literature data for the study of enantioselective processes in the environment.