Silica-based magnetic hybrid nanocomposite for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography.

The precise control of pesticide residues in foodstuffs depends significantly on the clean extraction of analytes using specifically designed separation methods. In this study, a one-pot sol-gel process was used for the preparation of a magnetic hybrid silica gel tetraethylortho silicate-cyanopropyltriethoxy silane nanocomposite. The prepared material was characterized using energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, single-point specific surface area, and scanning electron microcopy. The synthesized magnetic hybrid material was used as a solid phase extraction sorbent for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography with a microelectron capture detector. The performance of the proposed magnetic solid-phase extraction technique was validated by linearity (0.05-2 ng/mL), correlation coefficients (r2  = 0.9993-0.9997), limit of detection (0.02-0.06 ng/mL, S/N = 3, n = 3), and intraday (RSD = 1.5-8.7%, n = 3) and interday precision (RSD = 5.5-9.3%, n = 12), while the recovery in real samples and equilibrium adsorption capacity was 72.02-103.84% and 8-20 mg/g, respectively. The magnetic solid-phase extraction based on the hybrid nanocomposite revealed a high enrichment factor, an appropriate dynamic range, and great absorptive ability toward the selected organophosphorus pesticides spiked in real water samples.