Electrospun poly(ST-Co-AC)/Co-ZIF-67@Chitosan composite nanofibers as a sorbent with superior reusability for pesticide residues analysis in food samples

Pollution caused by pesticides have attracted huge attention, and it is of a great significance to develop sensitive methods for trace monitoring these analytes in complicated matrices. Herein, the composite of styrene acrylonitrile copolymer p(St-Co-AC)/zeolitic based metal–organic frameworks (Co-ZIF-67)/Chitosan (CS) electrospun nanofibers was fabricated by using an electrospinning approach. The resultant composite nanofibers were characterized to apply as a novel adsorbent for pipette tip micro solid-phase extraction (PT- μSPE) of four pesticides prior to GC-FID analysis. Incorporating Co-ZIF-67@Chitosan into p(ST-Co-AC) results in increasing the porosity features and surface area of the nanofibers. The effect of different main parameters on extraction efficiency was evaluated. Under the optimal conditions, linearity ranges were 1.5–2000.0 ng mL−1 for ethofumasate, 2.0–2000.0 ng mL−1 for ametryn and propazine, and 3.0–2000.0 ng mL−1 for tribenuron-methyl (R2 = 0.9951–0.9997). The LODs (according to S/N = 3) were calculated in the range of 0.5 to 1.0 ng mL−1.The relative standard deviations (RSDs) were obtained between 5.1 % – 6.1 % (intra-day, n = 5) and 5.6 %–6.4 % (inter-day, n = 3) for three sequential days. The developed method was investigated in food samples including apple, tomato, honey, and milk, and achieved recoveries (88.1–95.2 %) indicated that the fabricated sorbent could be a promising composite for the pre-concentration of pesticides in various matrices.