An ionic liquid-magnetic graphene composite for magnet dispersive solid-phase extraction of triazine herbicides in surface water followed by high performance liquid chromatography

Abstract

A new ionic liquid-magnetic graphene (IL-MG) composite was used as the adsorbent in magnetic dispersive solid-phase extraction to rapidly extract and isolate triazine herbicides from surface water. IL-MG was synthesized by a simple and time-saving one-pot strategy where the synthesis of magnetic Fe₃O₄, the modification with an IL, and the reduction of graphene oxide to graphene were conducted at the same time. An IL was applied to enrich the interaction mechanism between IL-MG and analytes (π–π, hydrophobic interaction, and electrostatic interaction). Moreover, the IL and Fe₃O₄ nanoparticles acted as spacers, inserting between the layers of graphene to prevent the aggregation of graphene, which improved the adsorption ability because of the large specific surface area of IL-MG. The resultant IL-MG had hierarchical flake structures and showed a high adsorption capacity (8266.0–12 324.1 μg g⁻¹) toward triazine herbicides. Under suitable conditions, the linearity for triazine herbicides was achieved in the range of 0.55–500 ng mL⁻¹ with a detection limit of 0.09–0.15 ng mL⁻¹ and a quantitation limit of 0.31–0.51 ng mL⁻¹, and the enrichment factor was 83-fold, which indicated that the proposed method could be successfully applied for the determination of triazine herbicides in surface water.