An alginate-based eutectogel impregnated with polyvinylpyrrolidone/benzoic acid deep eutectic solvent and magnetic carboxylated multiwalled carbon nanotubes: Evaluated as sorbent in green microextraction of pesticides

This article presents the synthesis and application of a novel magnetic eutectogel constituting a polymeric deep eutectic solvent (PDES), carboxylated multiwall carbon nanotube (MWCNT-COOH), and super-dispersible/super-paramagnetic polyvinylpyrrolidone coated-Fe₃O₄ nanocrystals incorporated in alginate gel. Different methods were used for the characterization of novel polymeric based DES gel including FT-NMR, ATR-FTIR, and SEM were used. The novel DES eutectogel was used for the extraction of pesticides from honey. The modified eutectogel with PDES, MWCNT, and PDES-MWCNT showed 1.8-, 1.4-, and 2.5-fold enhancement in the sorption efficiency under green magnetic micro-solid-phase extraction (MSPE) method before GC–MS analysis. Important factors including the acidity of the samples, adsorption and desorption conditions, and the ionic strength of the preparation solution were investigated. The matrix effect, specificity, the quantification limits (0.023–1.023 μg kg⁻¹), linear dynamic range (0.023–500 µg kg⁻¹ with R² of 0.9845–0.9986), relative standard deviations (<8.4%), were evaluated. In addition, the method was used to analyze 12 pesticides in four samples of honey. In the spiked concentration range of 0.1 to 10 μg kg^-, the obtained recoveries were between 73.2 and 110.8% (RSD% = 8.1%, n = 3).