Evaluation of the potential of a quinidine-based monolithic column on the enantiomeric separation of herbicides by nano-liquid chromatography

• Poly(MQD-co-HEMA-co-EDMA) monolithic column was prepared for its use in nano-LC.
• Enantiomers of seven phenoxy acid herbicides were separated.
• Mecoprop enantiomers were separated from other three achiral herbicides.
• R-Mecoprop was quantified in commercial herbicide formulations.
• Enantiomeric impurity of R-mecoprop commercial formulation was below the LOQ.

The use of agrochemicals as pure enantiomers avoids the presence of non-active pesticide compounds in the environment. The quality control of these agrochemicals requires the development of new chiral methodologies. In this work, the performance of the monolithic column named poly(O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine-co-2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (poly(MQD-co-HEMA-co-EDMA)) was assessed as stationary phase for the enantiomeric separation of seven phenoxy acid herbicides (dichlorprop, 2-(4-chlorophenoxy)propionic acid, 2-(3-chlorophenoxy)propionic acid, mecoprop, fenoprop, 2-phenoxypropionic acid, and fenoxaprop) in a nano-liquid chromatography (nano-LC) system. Under optimized conditions (60/40 (v/v) ACN/0.1 M ammonium acetate (pH 6.0) at a flow rate of 20 μL/min), it was possible to obtain baseline separation for most of the studied compounds. The analysis of an enantiomerically pure mecoprop commercial herbicide sample which also contained three achiral phenoxy acid herbicides (MCPA, 2,4-D and dicamba) commonly present in these kinds of formulations showed that the use of a 80/20 (v/v) ACN/0.1 M ammonium acetate (pH 5.3) enabled the simultaneous separation of these compounds and mecoprop enantiomers in less than 8 min. The analytical characteristics of the methodology were evaluated in terms of selectivity, linearity, precision, accuracy, LOD, and LOQ. Results demonstrated that determined amounts of R-mecoprop in commercial formulations were in agreement with the labeled content and the enantiomeric impurity was below the LOQ. The poly(MQD-co-HEMA-co-EDMA) capillary monolithic column exhibits great potential as a useful and environmental-friendly tool for the quality control of agrochemicals by nano-LC.