<p>In this work, the synthesis of molecularly imprinted polymers was carried out using allyl alcohol as functional monomer. The developed materials were characterized morphologically using confocal microscopy and electron microscopy (scanning and transmission). Furthermore, a chemical characterization of the polymers was performed using Fourier transform infrared spectroscopy (FTIR) and BET analysis with the intent of verifying the presence of functional groups and determining the specific surface areas. Aiming to prove that the developed polymer has selective and sensitive adsorption to 3,4-DCA, it was proposed an electrochemical sensor modified with Fe₃O₄@MIP. Under optimal analysis conditions using square wave voltammetry (SWV), the sensor showed a linear response range from 5.0 × 10⁻⁷ to 1.6 × 10⁻⁵&#xa0;mol L⁻¹ and a detection limit of 3.2 × 10⁻⁸&#xa0;mol L⁻¹. The selectivity of the sensor was confirmed when compared with various chemical compounds. Finally, the sensor was applied to real environmental samples, where the results obtained were similar to the results obtained in the HPLC–UV (comparative method), demonstrating the viability of the proposed method.</p> Graphical abstract <p></p>