Innovative ferrofluid-based vortex-assisted dispersive liquid-liquid microextraction of cadmium and nickel using novel and natural hydrophobic deep eutectic solvent and 2-methylimidazole-coated magnetic nanoparticles

Abstract

This study presents a novel, natural, and cost-effective ferrofluid based on a deep eutectic solvent (DES), utilizing a new hydrophobic DES composed of menthol and octylamine as the carrier medium and magnetic nanoparticles with novel surface modification using 2-methylimidazole (2-MIM). The produced ferrofluid was characterized using FTIR, XRD, SEM, and SEM-EDX techniques. This ferrofluid served as an effective extraction solvent for the fast preconcentration and extraction of Cd(II) and Ni(II) from diverse actual samples utilizing vortex-assisted dispersive liquid–liquid microextraction (VA-DLLME) followed by flame atomic absorption spectrometry (FAAS). The optimization of key extraction parameters, such as pH, ferrofluid quantity, adsorption duration, and eluent characteristics, was conducted utilizing the one-variable-at-a-time (OVAT) approach. Under ideal conditions, the method exhibited a linear calibration range of 0.05–5.0 μg mL⁻¹, with determination coefficients (R²) of 0.9893 for Cd(II) and 0.9936 for Ni(II). The limits of detection (LOD) were 0.015 μg mL⁻¹, with relative standard deviations (RSDs) of 2.9 % (Cd(II)) and 2.6 % (Ni(II)) for intra-day precision, and 3.1 % (Cd(II)) and 4.9 % (Ni(II)) for inter-day precision. The approach attained preconcentration factors of 5.0, enrichment factors of 4.8 and 4.7, and extraction recoveries of 96 % and 94 % for Cd(II) and Ni(II), respectively. The methodology was corroborated utilizing certified reference materials (BCR-505, NCS ZC73032, and NIST 1573a). The DES-FF/VA-DLLME technique exhibited effective and swift extraction of Cd(II) and Ni(II) from aqueous and food matrices, providing a speedy, eco-friendly, and sustainable approach to analytical chemistry.