Quizalofop-P-Ethyl, a selective post-emergence herbicide registered for use in controlling annual and perennial grassy weeds in a variety of crops, is a compound with a single chiral carbon that is sold as the purified R enamtiomer. Like many other pesticides or plant protection products with chiral centers, residue methods for this compound are generally achiral. However, regulatory requirements for active ingredients with chiral centers have shifted in the European Union. New guidelines include chiral analysis during environmental fate, metabolism and potentially residue analysis to demonstrate lack of interconversion of a chiral active ingredient / metabolite and a less or non-active enantiomer.<br/>This presentation will focus on a case study development of two orthogonal approaches to separate and quantify the enantiomers of quizalofop-p-ethyl and its metabolite quizalofop acid. A structured chiral screening approach with routine mobile phase conditions was implemented on a variety of polysaccharide HPLC column chemistries functionalized with chiral selecting groups to rapidly target the best conditions for separation of the quizalofop-p-ethyl and quizalofop acid enantiomers. This structured chiral screening process was performed in reversed phase and polar organic conditions on 5 Lux® polysaccharide with general mass spectrometric compatibility, and then the optimal chemistry and conditions were run successfully with the previously optimized mass spectrometric parameters. In addition, chiral separation of the quizalofop-p-ethyl and quizalofop acid enantiomers was explored using SelexION® differential mobility spectrometry (DMS) which separates compounds based on their dipole moment influence on gas phase mobility in ion-source before Q1. An achiral C18 HPLC column was coupled with SelexION® DMS to simultaneously resolve their respective enantiomers.

Advanced Environmental Safety Assessments using Rapid Chiral Separation and Differential Mobility Spectrometry (DMS)

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.