Enantioselective Analysis of Chiral Agrochemicals with High-Performance Liquid Chromatography

This chapter illustrates the versatility of high-performance liquid chromatography (HPLC) chiral separation techniques to analyze chiral agrochemicals, often applied as racemic mixtures, and useful mathematical tools for the evaluation of stereoisomer degradation routes in the environment. Among the several chiral stationary phases, polysaccharide-based carbamate- or ester-functionalized ones are the most popular and effective, both in terms of enantioselectivity and chemoselectivity, proving to be potent analytical tools for studying chiral pesticides. In recent years, the tendency promoted by the European policies has led to the development of agrochemical formulations containing a single active enantiomer. The actual purity of such preparations and the degradation pathways of the involved chiral species can be studied through the procedures described here. In this perspective, enantioselective analyses allow one to verify the quality of the commercialized products and the degradation processes of involved stereoisomers in environmental and food samples. As a model analytical workflow, an enantioselective chromatographic method for the detection and quantitative assessment of quizalofop-ethyl and quizalofop, a post-emergence herbicide and its main metabolite, respectively, is presented here. The analytical procedure aims at following the chiral signature of these contaminants in the environmental sector, giving tools for the investigation of dispersive dynamics and natural degradation pathways of chiral species.