Fast and precise determination of .alpha.-hexachlorocyclohexane enantiomers in environmental samples using chiral high-resolution gas chromatography

Abstract

A high-resolution gas chromatographic method is described which allows the determination of the enantiomeric ratio of a-hexachlorohexane (HCH) in environmental samples within 18 min. A stationary phase with low bleeding was obtained by diluting permethylated heptakis(2,3,6-tri-O-methyl)-~-cyclodextrin in a OH-terminated polysiloxane. It allowed temperature programming with detection in the low-picogram range using electron capture detection and high-resolution mass spectrometry. The separation method is compatible with standard sample cleanup procedures, which facilitate the reanalysis of stored sample extracts. Detailed information is given about the preparation of the separation capillary, the analytical parameters, and the reproducibility of the quantification. Furthermore, the applicability of the method to different environmental samples is demonstrated. First results, which showed an excess of a(+)-HCH in all analyzed sample matrices, are discussed.

Environmental occurrence, analysis, and toxicology of toxaphene compounds.

“…The peak area/height of the (+)-enantiomer is divided by that of the (-)-enantiomer (120)(121)(122)(123). When the conformation of the enantiomers eluting from a chromatographic system is not known, as with enantiomers present in toxaphene, the ER is often expressed as the peak area/height of the first eluting enantiomer divided by that of the second (124).…”

Enantioselective Transformation of α-Hexachlorocyclohexane by the Dehydrochlorinases LinA1 and LinA2 from the Soil Bacterium Sphingomonas paucimobilis B90A

“…In technical HCH, ␣-HCH is present as a racemic (1:1) mixture of the two enantiomers (1). Enantiomer-specific analyses have revealed various enantiomer compositions of ␣-HCH in environmental and biological samples (5,9,10,16). Molecular details of enantioselectivity are known for a limited selection of chiral pollutants, but not very much is known about the mechanisms of the enantioselective metabolism of ␣-HCH or about the organisms and enzymes involved (17).…”

Enantiomeric separation by GC on chirasil‐dex: Systematic study of cyclodextrin concentration, polarity, immobilization, and column stability

“…1701 [28,29], but according to our experiments [30], film stabilities, coating properties, and minimal operating temperatures are extremely unfavorable under such conditions.) The previously reported Chirasil-Dex [7,12] corresponds to phase 2.…”