Evaluation of 2‐hydroxyethyl methacrylate as comonomer in the preparation of water‐compatible molecularly imprinted polymers for triazinic herbicides

Abstract

In this work, the preparation and evaluation of water‐compatible molecularly imprinted polymers for triazines using 2‐hydroxyethyl methacrylate and methacrylic acid as comonomers is described. Four sets of molecularly imprinted and non‐imprinted polymers for propazine were prepared at varying monomer molar ratios (from 4:0 to 1:3), and evaluated for the recognition of several triazines directly in aqueous media. The evaluation was performed by loading 1 mL of an aqueous solution containing 500 ng of each selected triazine, washing with 500 μL of acetonitrile, and eluting with 500 μL of methanol followed by 2 × 500 μL of a solution of methanol containing 10% of acetic acid. Final determinations were performed by high‐performance liquid chromatography‐ultraviolet detection. Improvement in molecular recognition of triazines in water was obtained on those molecularly imprinted polymers incorporating 2‐hydroxyethyl methacrylate in 3:1 or 2:2 molar ratios, being the former selected as optimum providing recoveries for propazine up to 80%. A molecularly imprinted solid‐phase extraction protocol was developed to ensure that triazines‐selective recognition takes place inside selective binding sites in pure water media. Finally, the developed method was successfully applied to the determination of the selected triazines in environmental waters providing limits of detection from 0.16 and the 0.5 μg/L concentration range.

Recent advances and future trends in molecularly imprinted polymers‐based sample preparation

“…Obtained results suggested that the inclusion of HEMA contributed to defining the imprinted sites and, in parallel, to create a more hydrophilic polymer matrix leading to the reduction of hydrophobic non‐specific interactions. Such conclusions were recently confirmed by the synthesis of a water‐compatible MIP, using HEMA as a co‐monomer, for the extraction of triazines from environmental waters [54]. By careful optimization of the HEMA:MAA ratio, a water‐compatible MIP is able to selectively extract 7 triazines from environmental waters with quantitative recoveries (>80%), whereas they drop to about 20% (depending upon the triazine under study) for conventional MIP using only MAA as functional monomer.…”

“…Peak assignment: (1) desisopropylatrazine; (2) desethylatrazine; (3) simazine; (4) cyanazine; (5) atrazine;(6) propazine; (7) terbuthylazine. Reproduced[54] with permission from John Wiley and Sons.…”