Promoting capillary microextraction of six organic nitrogen pesticides in water samples using versatile ZIF-8 hybrid monolithic column.

Because of rapid industrialization and agriculturalization, solving the pressing problems of environment pollution, especially water and food quality, requires innovative solutions. In this paper, a novel and versatile metal-organic framework (ZIF-8)-hybrid monolithic column (ZIF-HMC) was prepared for in-tube solid-phase microextraction (IT-SPME) of organic nitrogen pesticides (ONPs). The prepared monolithic columns had superior adsorption sites, high porosity, excellent permeability, and ideal specific surface area based on Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Thermal Field Emission Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), X-ray Photoelectron Spectroscopy (XPS), and N2 adsorption-desorption. The ZIF-HMC contained a large number of nitrogen and oxygen atoms, benzene rings and ZIF-8, which could synergistically promote the adsorption efficiency of ONPs through multiple interactions, such as hydrogen bonding, π-π accumulation, hydrophobic interactions, cation-π interactions, and pore adsorption by MOFs. Under the optimal conditions, a simple, efficient, and sensitive method for the analysis of six organic pesticides in environmental water samples was developed by using the ZIF-HMC as the extraction medium coupled with high performance liquid chromatography-ultraviolet (HPLC-UV). The method had a wide linear range (0.63-1000 μg L-1), a low detection limit (0.19-1.91 μg L-1) and satisfactory recoveries (87.4 %-110.2 %), the linear correlation coefficient was (R2) 0.9972-0.9995 and the relative standard deviation (RSD) was less than 2.64 %. The study had demonstrated the potential application of the developed method for the enrichment and analysis of organic pesticides in complex matrices of environmental samples, as well as the feasibility of MOFs materials for IT-SPME sample preparation.