SEPARATION AND ANALYSIS OF THE DIASTEREOMERS AND ENANTIOMERS OF CYPERMETHRIN AND RELATED-COMPOUNDS

The diastereomers of cypermethrin and permethrin have been resolved on an irregular silica column. Complete separation of three of the four enantiomeric pairs of cypermethrin was achieved with reasonable retent ion times (<50 min) by direct injection of the separated diastereomers onto a cellulose based chiral HPLC column. The order of elution was e stablished; structures were confirmed by NMR and comparison with the r etention times of authentic enantiomeric standards. For the unseparate d pair, improved resolution was achieved with a slightly longer retent ion time (80 min). injection of alpha-cypermethrin onto the chiral sys tem under the same conditions gave excellent separation of the two ena ntiomers. (C) 1997 Elsevier Science B.V.