Chiral separation of phenoxypropionic acid herbicides via capillary electrochromatography based on dummy template-chiral molecularly imprinted polymers.

BACKGROUND: Chiral molecularly imprinted polymers (CMIPs) represent highly promising stationary phases for capillary electrochromatography (CEC), particularly in the field of chiral separation. However, current CMIPs-CEC chiral separation systems are still limited by the "one template, one target" recognition mode, which fails to meet the practical demand for broad applicability in modern chromatographic techniques. The dummy template (DT) strategy is a highly promising direction to expand the recognition scope of molecularly imprinted polymers, and holds potential for achieving wider application of CMIPs-CEC systems. Notably, DT-CMIPs based CEC chiral separation systems have not yet been reported, and thus in-depth investigations are urgently needed.

RESULTS: In this work, a typical class of phenoxypropionic acid herbicides (PAHs) commonly used in agricultural production was selected as the target analytes. Using R-2-phenoxypropionic acid as the dummy template and itaconic acid as the functional monomer, a CEC monolithic column capable of chiral recognition of multiple PAHs was prepared via in situ radical polymerization inside a capillary. The developed CEC chiral separation system successfully achieved enantioseparation of ten PAHs (Rs = 0.58∼5.31). Although baseline separation was not fully accomplished for all analytes, this work represents an important attempt at a DT-CMIPs-CEC system. In addition, the relationship between the chiral selective adsorption performance of the stationary phase and the separation efficiency of the CEC system was preliminarily explored through static adsorption experiments.

SIGNIFICANCE: This work demonstrates the promising application of DT-CMIPs in CEC chiral separation systems, providing new insights and innovative attempts for the development of novel stationary phases and chiral separation methods in CEC. The results provide a robust and efficient platform for the rapid screening of chiral herbicide families and offer new insights into the rational design of advanced materials for complex enantioseparations in environmental and food analysis.