Abstract

A porous magnetic composite adsorbent was developed by incorporating hyper-crosslinked polymer-decorated graphene oxide (Fe<inf>3</inf>O<inf>4</inf>@HCP-GO) into alginate hydrogel beads, forming Fe<inf>3</inf>O<inf>4</inf>@HCP-GO alginate beads. For the first time, this unique hierarchical structure combining magnetic responsiveness, high surface area, and multiple adsorption mechanisms was engineered for the efficient extraction of phenylurea herbicides (PUHs). The material was applied in a dispersive liquid-solid phase extraction (DLSPE) process, enabling the simultaneous adsorption of six PUHs through hydrogen bonding, hydrophobic, and π-π interactions. The extracted PUHs were determined by high performance liquid chromatography. The fabricated porous adsorbent was characterized, and the extraction conditions were optimized. Under optimal conditions, the developed method exhibited linearity from 5.0 to 100 μg L⁻¹ for metoxuron, monuron, chlortoluron and buturon, and from 10 to 100 μg L⁻¹ for isoproturon and monolinuron. The limits of detection were between 1.0 and 3.0 μg L⁻¹. The developed adsorbent was utilized to extract PUHs from rice, cucumber and tomato, achieving recoveries ranging from 70.2 to 96.7 % with RSDs below 9.0 %. The fabricated porous magnetic composite hydrogel bead exhibited good stability and efficiency for up to 6 cycles of extraction and desorption.