Gas-liquid Chromatographic Determination of a New Pyrethroid, Permethrin (S-3151) and Its Optical Isomers

Abstract

Gas-liquid chromatographic (GLC) methods were developed for the determination of 3-phenoxybenzyl dl-cis, traps-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropane-1-carboxylate (S-3151, permethrin or Exmin ^®), its geometrical and optical isomers and its impurities. dl-Trans and dl-cis isomers were separated from each other on a 2% LAC-2 R-446 column and determined by using dioctyl phthalate as an internal standard, and the overall content of S-3151 was obtained by the sum of them. Optical isomers, namely, d-cis, l-cis, d-trans and l-trans forms were hydrolysed to the corresponding acids, which were derivatized to the diastereoisomer esters with d- or l-2-octanol and separated from one another on a 10% silicone DC QF-1 column. The optical isomer ratios were determined by the peak area ratios. The impurities of S-3151 were identified by mass spectrometer combined with GLC on a 2% PEG-20M column and they were determined by programmed temperature GLC.