Cypermethrin is a widely used pesticide. Theoretically, it has 4 pairs of stereo isomers or 8 enantiomers. Based on the route of synthesis, the products could contain some particular isomers only. EPA registered alpha, beta, theta and zeta Cypermethrins for different usage and tolerance.  Most GCMS and LC-MS/MS methods for multi-residue analysis can cover Cypermethrin as a summary of all isomers. If it is necessary to quantitate some particular isomers, some chiral chromatography separation methods were available. Although these methods can get good separation, the isomers were identified wrong from literature due to lacking of pure isomer standards of Cypermethrins.  This study analyzed pure alpha, beta, theta and zeta Cypermethrins with LC-MS/MS and GCMS. The purity of each standard was 95% or higher. Because alpha, beta and theta Cypermethrins are pairs of stereo isomers, the methods did not use chiral columns. The separation and sensitivity were good for regulatory analysis. The methods could be used for Cypermethrin residues, the mix of pyrethroids' residues or together with other multi-residues' analysis.

Cypermethrin isomers separation and quantitation with LC-MS/MS

248th National Meeting (2014)

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