Magnetic dispersive solid-phase microextraction for determination of two organophosphorus pesticides in cucumber and orange samples

In this study, a magnetic dispersive solid-phase microextraction technique based on chitosan–iron oxide magnetic nanocomposite (CS@Fe3O4) as sensitive and inexpensive sorbent was developed for the preconcentration and simultaneous determination of malathion and fenitrothion in fruit and vegetable samples before determining with GC–FID. The structures, morphologies, and properties of the nanocomposite were characterized by Fourier transform infrared, transmission electron microscopy, and scanning electron microscopy. The significant factors such as pH, sample solution volumes, extraction time, the type and amount of nanocomposites, type and volume of desorption solvent, and desorption time were investigated and optimized. One factor at the time and an experimental design approach were utilized to optimize the selected factors. In the optimal conditions, the linear range for malathion and fenitrothion was 1.0–400.0 and 3.4–600.0 µg L−1 with a suitable R2 (≥ 0.992), respectively. The intra-day and inter-day relative standard divisions (RSDs) were lower than 4.83 and 4.90 for both analytes, respectively. Limit of detection for the determination of malathion and fenitrothion was 0.3 and 1.0 ng mL−1, respectively. The proposed method showed a high recovery percentage in the range of 95.8–106.0 and low RSDs (≤ 5.0) for the determination of malathion and fenitrothion in the cucumber and orange samples.