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PH07 Environmental Chemistry and Toxicology of Chiral Pollutants
(PH071) Separation and isolation of enantiomers of current chiral insecticides by HPLC.
Liu, Weiping 1, Qin, Sujie1, Gan, Jay1, 1 University of California-Riverside, Riverside, California, USA
ABSTRACT- The significance of molecular chirality in life sciences has long been recognized. About 25% of currently used pesticides are chiral, and this ratio is increasing as pesticides with more complex structures are introduced. Because of a general lack of enantiomer standards, one of the biggest challenges in studying enantioselective behavior of pesticides has been separation and identification of enantiomers. In this paper, a number of currently used chiral pesticides, including synthetic pyrethroids and organophosphates, were separated by high-performance liquid chromatography using enantioselective columns. Separation of (Z)-cis-bifenthrin (BF) and permethrin (PM) was achieved on a SUMICHCHIRAL OA-2500I column and using 0.2-0.5% 1,2-dichloroethane in hexane as the mobile phase. Enantiomers in both cis-BF and cis-PM were separated at the baseline, while enantiomers in trans-PM were partially separated. Enantiomers in cypermethrin (CP) and cyfluthrin (CF) were perfectly separated on two CHIREX OOG-3019-DO columns chained together using different ratios of hexane, 1,2-dichloroethane and ethanol. Enantiomers in five organophosphate insecticides (fonofos, malathion, crotoxyphos, trichoronate and profenofos) were completely separated on a CHIRALCEL OJ column using 0.5-5% denatured ethanol (5% methanol and 5% 2-propanol) in n-hexane as mobile phase. The adequate separation allowed the resolved enantiomers to be isolated and recovered for use in assessment of enantioselectivity in aquatic toxicity. Reanalysis of the isolated enantiomers under the same conditions indicted (enantiomer) purities of >99% for cis-BF, cis-PM, CP, CF and OPs and >97% for trans-PM. The obtained enantiomer may be used as analytical standards.
Key words: synthetic pyrethroids, chiral insecticide, organophosphates, separation
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