GAS-CHROMATOGRAPHIC DETERMINATION OF OPTICAL ISOMERS OF 2-(4-CHLOROPHENYL)ISOVALERIC ACID

Gas chromatographic methods were developed for the determination of optical isomers of 2-(4-chlorophenyl)isovaleric acid (CPIA) which constituted the acid moiety of the insecticide Fenvalerate molecule. The enantiomers of CPIA were derivatized into diastereoisomeric Amenthyl esters quantitatively via their acid chlorides and separated from each other on a column of 10% silicone DC QF-1 (3 mm i.d.x 2.25 m). They were also derivatized into isopropylamides in the presence of A'-dicyclohexylcarbodiimide and were resolved on an open tubular glass capillary column (0.25 mm i.d. x 40 m) coated with optically active N, N‘'-[2,4-06-ethoxy-1,3,5-triazine)diyl] bis(L-valyl-L-valyl-L-valine isopropyl ester) (OA-300). The ratios of optical isomers were determined from their separated peak areas and analytical values obtained by two methods were in good agreement with each other. The chemical purity of CPIA was also determined by gas chromatography after derivati- zation to its methyl ester on a column of 2% DEGS (3 mm i.d.x 3 m) using /w-nitroanisole as an internal standard. © 1979 Taylor & Francis Group, LLC.