SummaryThe enantiomers of phenoxypropionic acid type herbicides have been resolved by capillary gas chromatography employing modified cyclodextrins as chiral stationary phases. Excellent separations were obtained with columns containing a 1 :I mixture of per-0-pentylated and per-0-methylated 6-cyclodextrin.pesticides and herbicides may differ by orders of magnitude, but little is known about their selective action. It has been found that the activity of the D( +) forms of some chiralphenoxypropionic acid derivatives (1-3; Figure 1) which are used as herbicides is about twice as high as that of the racemates.The enantiomers of the methyl esters of mecoprop and dichlorprop were also resolved on octakis(3-O-butyryl-2,6-di-O-penty1)y-cyclodextrin. On this phase the order of elution of the enantiomers was temperature-dependent, the elution order being reversed as the temperature passed through the isoenantioselective temperature. This is the first time such behavior has been observed with cyclodextrin derivatives.The enantiomers of the polychlorinated polycyclic pesticides cis-and trans-chlordane, oxychlordane, heptachlor, heptachlorepoxide, and three chiral organophosphorus pesticides could be resolved using selectively derivatiied cyclodextrin derivatives.

Enantiomeric ratios of 11 chiral environmental pollutants determined in different compartments of the marine ecosystem by chiral capillary gas chromatography and chiral high-performance liquid chromatography allow discrimination between the following processes: enantioselective decomposition of both enantiomers with different velocities by marine microorganisms (alpha-HCH, beta-PCCH, gamma-PCCH); enantioselective decomposition of one enantiomer only by marine microorganisms (DCPP); enantioselective decomposition by enzymatic processes in marine biota (alpha-HCH, beta-PCCH, trans-chlordane, cis-chlordane, octachlordane MC4, octachlordane MC5, octachlordane MC7, oxychlordane, heptachlor epoxide); enantioselective active transport through the "blood-brain barrier" (alpha-HCH); nonenantioselective photochemical degradation (alpha-HCH, beta-PCCH).

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SUMMARY Background and AimThe outcome of gastro-oesophageal reflux disease treatment is traditionally assessed by measuring endoscopically confirmed healing and symptom relief separately. Both terms together, indicating complete remission, are intuitively a more realistic clinical endpoint but are assessed less often.

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