Detection of S-metolachlor herbicide in water samples using new molecularly imprinted polymer for solid-phase extraction

The application of herbicides has been proven to enhance crop yield. Nevertheless, the use of plant protection products has been associated with the migration of chemicals into water systems, thereby reducing their quality. The present study proposes a novel methodology for the detection of S-metolachlor within water samples, utilizing pH-sensitive molecularly imprinted polymers (MIPs) as highly selective and sensitive sorbents. The MIPs demonstrated a higher absorption capacity of S-metolachlor (0.75 ± 0.34 mg × g −1 ) in comparison to the non-imprinted polymers (0.17 ± 0.04 mg × g −1 ). The adsorption isotherms were analyzed using the Freundlich, Langmuir, Dubinin-Radushkevich, and Scatchard models. The Scatchard model was found to be the best fit, as the parameters obtained were closest to the experimental values, confirming the heterogeneity of the binding sites present on the MIP surface. The data obtained from the kinetic study were fitted to the pseudo-first-order and pseudo-second-order models. The pseudo-second-order model provided the most appropriate fit (R 2 = 0.998). The obtained sorbent exhibited high selectivity for S-metolachlor, absorbing it approximately 3 times better than atrazine, 2,4-dichlorophenoxyoctic acid (2,4-D), and mesotrione. The results indicate that pH-sensitive molecularly imprinted polymers, exhibit excellent sensitivity and selectivity towards S-metolachlor, making them a novel material for preconcentrating and determining the concentration of sample. • SPE columns with smart green MIPs for selective determination of S-metolachlor • The sensor was employed in the analysis in model and tap water metolachlor solutions. • Sorbents can be recycled 2 times with an average recycling rate of 96 %.