betadex and bifenthrin

The first CE method enabling the enantiomeric separation of the synthetic pyrethroid cis-bifenthrin (BF) was developed in this work. CD-MEKC was the CE mode employed for this purpose. The influence of several experimental parameters such as temperature, voltage, type and concentration of surfactant (chiral and achiral) and CD was investigated. The use of the bile salt sodium cholate at a concentration of 100 mM in the presence of 20 mM heptakis (2,3,6-tri-O-methyl)-beta-CD enabled the separation of cis-BF enantiomers in less than 10 min and with a resolution of 2.8. The analytical characteristics of the developed methodology were evaluated allowing its application to the quantitation of cis-BF in a polyvalent commercial insecticide formulation.

Topics: beta-Cyclodextrins; Chromatography, Micellar Electrokinetic Capillary; Insecticides; Linear Models; Pyrethrins; Reproducibility of Results; Sodium Cholate; Stereoisomerism; Temperature

Solid phase microextraction (SPME) is an ideal sample preparation technique because of its speed and solvent-free features. Sampling by SPME is selective and only the dissolved concentration is measured, which allows measurement of the bioavailable fraction of a contaminant in aqueous media. One potential application of SPME is for analysis of enantiomers of chiral contaminants in environmental samples. In this study, a method was developed for determining enantiomers of (Z)-cis-bifenthrin and cis-permethrin in water using coupled SPME and enantioselective gas chromatography (GC). Following SPME sampling, enantiomers of (Z)-cis-bifenthrin and cis-permethrin were separated at the baseline on a beta-cyclodextrin-based enantioselective column, and analyte enrichment onto the SPME fiber was not enantioselective. The GC response increased as sampling time was increased from 0 to 240 min, and as sampling temperature was increased from 20 to 40 degrees C. Organic solvents such as methanol, acetone, and acetonitrile enhanced, while soil extracts slightly decreased, the GC response. The integrated SPME-enantioselective GC method was used to analyze surface runoff samples. The analysis showed preferential degradation of the 1S-3S enantiomer over the 1R-3R enantiomer for both (Z)-cis-bifenthrin and cis-permethrin. The concentrations detected by SPME-GC were substantially smaller than those determined following solvent extraction, suggesting that SPME-enantioselective GC analysis selectively measured the dissolved fraction.

Topics: beta-Cyclodextrins; Chromatography, Gas; Cyclodextrins; Permethrin; Pyrethrins; Sensitivity and Specificity; Soil; Stereoisomerism; Water; Water Pollutants