ENANTIOSELECTIVE DETERMINATION OF CHLORDANE COMPONENTS, METABOLITES, AND PHOTOCONVERSION PRODUCTS IN ENVIRONMENTAL-SAMPLES USING CHIRAL HIGH-RESOLUTION GAS-CHROMATOGRAPHY AND MASS-SPECTROMETRY
Hr. Buser et Md. Muller, ENANTIOSELECTIVE DETERMINATION OF CHLORDANE COMPONENTS, METABOLITES, AND PHOTOCONVERSION PRODUCTS IN ENVIRONMENTAL-SAMPLES USING CHIRAL HIGH-RESOLUTION GAS-CHROMATOGRAPHY AND MASS-SPECTROMETRY, Environmental science & technology, 27(6), 1993, pp. 1211-1220
Enantiomer separation of various chlordane compounds, including heptac
hlor, the oxygenated metabolites heptachlor epoxide (HEP) and oxychlor
dane (OXY), and photoconversion products was investigated using chiral
high-resolution gas chromatography and detection by electron ionizati
on (EI) and electron-capture, negative ionization (ECNI) mass spectrom
etry (MS). In technical chlordane and in ambient air from Scandinavia,
heptachlor and the chiral octa- and nonachlordanes were present in en
antiomeric ratios of 1:1. The results indicate input of these compound
s via aerial transport into the northern environment as racemic mixtur
es. Laboratory experiments using solid-phase photolysis by natural sun
light yielded caged and half-caged products from heptachlor and cis-ch
lordane, respectively. HEP was identified as a photooxidation product
of heptachlor and formed in an enantiomeric ratio of 1:1. In contrast,
incubation of heptachlor with rat liver homogenate (S9 fraction) yiel
ded predominantly one enantiomer of HEP, likely due to the stereoselec
tivity of the mixed-function oxidase system. Biota from the Baltic (fi
sh, seal), Arctic (seal), and Antarctic (penguin) showed changed isome
ric and enantiomeric compositions of the octa- and nonachlordanes as c
ompared to technical chlordane, and the metabolites HEP and OXY presen
t in enantiomeric ratios differing from 1:1. The finding of photohepta
chlor and photo-cis-chlordanes in these species document that photorea
ctions of chlordane compounds play a role in the transformation of the
se compounds in the environment.