DEVELOPMENT AND OPTIMIZATION OF HPLC METHODS FOR THE CHIRAL SEPARATION OF ARYLPYRAZOLE, CHLOROACETANILIDE AND ORGANOCHLORINE PESTICIDES: CASE STUDIES OF BENZOBICYCLON, ACETOCHLOR AND CHLORDANE.

Abstract

This work is centered on the development and optimization of High-Performance Liquid Chromatographic methods for the separation of chiral pesticides, particularly benzobicyclon, chlordane and acetochlor employing Agilent Technologies Infinity II chiral HPLC system equipped with a UV – 2000 detector. The stereoisomers were successively separated using a standard analytical column of dimensions 250 mm X 4.6 mm. The Cis– stereoisomers of chlordane exhibited partial baseline separation while the Trans – enantiomers were fully separated. Benzobicyclon and acetochlor enantiomers attained full baseline separation under optimized conditions. Chlordane and benzobicyclon were analyzed using normal phase chromatography [NP]c with a mobile phase of 90% Normal hexane and 10% Isopropanol, while acetochlor was analyzed by reverse phase chromatography [RP] c using 70% methanol and 30% water. Benzobicyclon was later spiked into soil sample and subsequently extracted using Environmental Protection Agency (EPA) methods and the extracts were further analyzed with a shorter analytical column of dimensions 75 mm X 4.6 mm. The HPLC separation revealed that the longer column provided more efficient separation for the benzobicyclon stereoisomers than the shorter column as reflected by high separation factors (?). The high recovery rate of the stereoisomers of benzobicyclon and the internal standard from the soil extracts confirmed the effectiveness of the method of extraction and the HPLC system employed.