Synthesis of magnetic poly (acrylic acid-menthol deep eutectic solvent) hydrogel: Application for extraction of pesticides

A novel magnetic deep eutectic solvent (DES)-based polymeric hydrogel was synthesized via a facile and rapid (in 4 min) thermal frontal polymerization, using acrylic acid-menthol DES (as a functional monomer), ammonium persulfate (as initiator), and acrylic acid-Fe3O4 nanoparticles (as cross-linker). The hydrogel was characterized by FTIR and FE-SEM techniques and utilized as a sorbent in magnetic solid-phase microextraction coupled with GC–μECD for the determination of 16 pesticides. Significant parameters such as sorbent dosage, desorption conditions, adsorption time, pH, and ionic strength were investigated and optimized. The validation results showed that this polymer could act as an excellent sorbent for pesticides. The LODs were in the range of 0.002–0.120 μg L−1, and the linear range was between 0.003 and 20 μg L−1. The enrichment factors were obtained from 152 to 550. The intra-day (n = 6) and inter-day (n = 4) RSDs were in the ranges of 0.8–6.8% and 2.4–17.3%, respectively. The performance and extraction efficiency of DES hydrogel were compared with those of DES functional monomer. Finally, the optimized method was applied for the determination of pesticides in different real environmental water samples, and the obtained recoveries were in the range of 61.0–120.0%.