Ultra-fast ultrasound-assisted synthesis of pyridine-based microporous organic network for pipette-tip solid-phase extraction of triazine herbicides in water: An experimental and adsorption mechanism study

Microporous organic networks (MONs) are an emerging class of adsorption materials with promising application prospects in sample pretreatment. However, their extensive application is frequently restricted by their traditional synthesis methods and limited variety. In this work, a pyridine-based microporous organic network (PMON) was synthesized using an ultra-fast ultrasonic synthesis (US), employing 3,5-dibromopyridin-2-amine and 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine as monomers. Characterization results from X-ray photoelectron spectroscopy, density functional theory, and independent gradient model evaluations confirmed that hydrogen bonding plays a significant role in the interaction between US-PMON and triazine herbicides. The prepared US-PMON was utilized as a pipette-tip solid phase extraction adsorbent in conjunction with gas chromatography-mass spectrometry for the determination of 10 triazine herbicides in water samples. Under optimal conditions, good linearities were obtained in the range of 0.5–100 ng/L, with low detection and quantification limits for the 10 triazine herbicides ranging from 0.02 to 0.20 ng/L and 0.07 to 0.66 ng/L, respectively. Satisfactory method recoveries, ranging from 78.2% to 110.4% were obtained after a 6 min extraction. This study provided a feasible sample pretreatment method for monitoring triazine herbicides in environmental water samples.