Chiral HPLC Resolution of Neutral Pesticides

The direct HPLC resolution of two synthetic neutral pesticides, Metolachlor and Ethofumesate, was studied on silica gel coated with cellulose tris-(3,5-dimethylphenylcarbamate) derivative (Chiracel OD-H). The specific composition of the mobile phase has allowed the full separation of the four Metolachlor stereoisomers, which had not previously been resolved on other chiral stationary phases. The isomer elution sequence of both resolved pesticides was determined by 1H NMR and polarimetric analyses. The chromatographic system, coupled with mass-spectrometric detection, was used to determine the isomeric ratio of Metolachlor stereoisomers after incubation in soil.