Synthesis and utilization of mixed-metal (Zn/Cd) metal-organic frameworks for ultra-trace determination of diazinon and ethion via ion mobility spectrometry.

A novel mixed-metal (Zn/Cd) metal-organic framework-based dispersive solid-phase microextraction (MM-MOFs-DSPME) method was developed for the efficient extraction of organophosphorus pesticides, diazinon and ethion, from various environmental matrices. The detection of the extracted analytes was performed using ion mobility spectrometry. The synthesized mixed-metal (Zn/Cd) MOF was characterized using a comprehensive array of analytical techniques: Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy (XPS), and zeta potential measurement. This comprehensive characterization provided an in-depth understanding of the material's structural and functional properties. Key parameters influencing the efficiency of the dispersive solid-phase microextraction (DSPME) method were optimized, including pH, type of desorption solvent, buffer type and volume, sorbent amount, and adsorption and desorption time. Under these optimal conditions, the linear dynamic ranges obtained were 0.5 to 300 ng mL for diazinon and 1.0 to 300 ng mL for ethion, with limits of detection of 0.15 ng mL and 0.29 ng mL, respectively. Preconcentration factors of 74% and 78%, with extraction recoveries of 98.4-104.2% and 96.6-103.4%, were achieved for diazinon and ethion, respectively. The relative standard deviations, calculated based on ten replicate measurements, yielded values of 3.8% for diazinon and 3.9% for ethion at a concentration of 10 ng mL, and 2.2% for diazinon, and 1.6% for ethion at a concentration of 150 ng mL, respectively. The developed method was successfully applied to the quantification of the target pesticides in soil, water, and apple samples.