Preparation of garlic-straw biochar-based surface molecularly imprinted polymers for solid-phase extraction of neonicotinoid insecticides from agricultural products

In this study, novel garlic-straw biochar-based surface molecularly imprinted polymer (GSBC@MIP) hybrid materials were prepared <i>via</i> a surface imprinting technology. The imprinted polymers were confirmed to polymerize on the surface of GSBC with an alveolate structure using a series of characterization instruments. Based on the beneficial synergistic effect, the hybrid materials presented fast adsorbing equilibrium (5 min), large adsorption capacity (48.8 mg g^-1) and selective recognition performance towards neonicotinoid insecticides. The obtained GSBC@MIP hybrid materials were applied in a solid phase extraction process, and their effectiveness was carefully investigated using various adsorption and desorption parameters. Under optimal conditions, an SPE process based on GSBC@MIP adsorbents coupled with high-performance liquid chromatography for extracting and determining targeted insecticides in agricultural samples was established. A good linear range (0.1-20 µg g^-1) with <i>R</i>² ≥ 0.9917 and limits of detection in the range of 8.1-45.0 ng g^-1 were obtained. The spiked satisfactory recoveries were in the range of 71.0-98.7% with the RSDs of 0.3-4.7% from fruits and vegetables (tomato, apple, pear, cucumber, grape, and cabbage). The developed method was validated to be sensitive, convenient and specific in analyzing neonicotinoid insecticides from complex agricultural samples based on the synergistic effect of imprinted polymers and garlic-straw biochar. More importantly, this study provides a tremendous potential adsorbent, which will be a reference for further broadening more selective biochar hybrid materials from agricultural wastes into the sample pretreatment process.