A green miniaturized QuEChERS based on an electrospun nanofibrous polymeric deep eutectic solvent coupled to gas chromatography-mass spectrometry for analysis of multiclass pesticide residues in cereal flour samples

A new polymeric deep eutectic solvent (DES) composed of poly (2-hydroxyethyl methacrylate):1-tetradecanol ([PHEMA]:[TD]) was prepared through thermally-induced free-radical polymerization using azobisisobutyronitrile (AIBN) as initiator. The [PHEMA]:[TD] DES was mixed with polyamide 6 (PA6) and electrospun into a composite fibrous scaffold for the first time. The PA6/[HEMA]:[TD] nanofibers were characterized by ATR-FTIR, SEM, BET, and BJH techniques and applied as a sorbent in the micro-solid phase extraction (µSPE) step of pesticide residues from cereal flour samples. The analyses were carried out with the GC–MS technique. The effect of sorbent mass, desorption solvent (kind and volume), pH, and ionic strength was investigated to establish the optimal conditions. Besides, the factors influencing the performance of the electrospinning process, such as electrospinning voltage, polymer solution feed rate, syringe needle tip-to-collector distance, and electrospinning duration, were also optimized. Matrix-matched calibration curves showed good linearity (r2 = 0.9803–0.9984) in the concentration range of 0.016–250 μg kg−1. The obtained limits of quantification (0.016–1.805 μg kg−1) were lower than the maximum residue levels (MRLs) established by the European Union and the Food and Agriculture Organization (0.01–0.05 mg kg−1) for the pesticide residues in cereal samples. The intra-day and inter-day precision based on relative standard deviation (RSD) were obtained as 1.1–5.8% and 2.4–8.5%, respectively. The method was applied to the detection of multiclass pesticide residues in maize, rice, wheat, and pastry flour samples, and the obtained relative recoveries were in the range of 71–118% (RSD%<7.5). Finally, the procedure greenness was evaluated based on Complex Green Analytical Procedure Index (Complex GAPI) and the Analytical Eco-Scale (AEC) approaches. This paper also suggests the first application of green hydrophobic PA6/[PHEMA]:[TD] electrospun nanofibers as sorbent for analyzing pesticides in different cereal samples.