Use of 6-O-tert.-butyldimethylsilylated beta-cyclodextrins for the enantioseparation of chiral organochlorine compounds

Enantioseparations of 26 chiral organochlorine compounds (alpha-hexachloroc yclohexane, toxaphene, chlordane, atropisomeric polychlorinated biphenyls) were studied with GC-electron-capture detection. The chiral stationary phas es (CSPs) consisted of 35% heptakis (6-0-tert.-butyldimethylsilyl-2,3-di-O- methyl)-beta-cyclodextrin (beta-TBDM) diluted in OV1701. One CSP was made o f pure beta-TBDM (purity>99%) while the other was randomly silylated beta-T BDM. High-temperature gas chromatography showed that this CSP contained fiv e products in almost equal amounts. Both beta-TBDM columns were installed i n parallel in the same GC system. On the randomly silylated beta-TBDM, arom atic compounds had shorter and aliphatic compounds had longer retention tim es than on the purified beta-TBDM. The randomly silylated beta-TBDM resolve d the enantiomers of 24 compounds (16 of them were baseline separated) and the purified beta-TBDM only six (four of them were baseline separated). Thu s, the purification of beta-TBDM decreased the efficiency of the chiral res olution of organochlorine compounds on beta-TBDM. The results clearly demon strate that the randomly silylated beta-TBDM contains one or more side prod ucts more suitable for the enantioseparation of organochlorine compounds th an the purified beta-TBDM. (C) 1999 Elsevier Science B.V. All rights reserv ed.