Hydroxyl group-enriched microporous organic network for high-performance solid-phase extraction of triazine herbicides: Experiment and DFT calculation on adsorption behavior

High-efficiency monitoring of triazine herbicides residues is vital in the evaluation of environmental and agro-food safety. Herein, we fabricated a spherical hydroxylated microporous organic network (OH–MON) with high surface area, high stability and rich hydrogen-bonding affinity sites suitable as an advanced solid-phase extraction (SPE) adsorbent for efficient adsorption of triazine herbicides. Density–functional theory calculations and competitive enrichment tests confirmed that hydrogen bonding played a vital role to the enrichment of triazine herbicides by OH–MON. This OH–MON SPE cartridge showed satisfactory reproducibility, maintaining its adsorption capacity after 10 adsorption–desorption cycles. Furthermore, we developed a sensitive analytical approach for determining triazine herbicides residues in water and fruit juice samples. Desirable linear correlations within 0.50–250 ng⋅L-1, an ultra-low detection limit (0.03–0.15 ng⋅L-1 for water; 0.04–0.21 ng⋅L-1 for fruit juice), good precision and high enrichment factor for triazine herbicides were achieved. A preliminary practical application of the developed method was proved by the efficient detection of triazine herbicides in water and fruit samples with good recoveries (72.8%−100.4% and 72.0%−97.7% for water and juice samples, respectively). This study serves as a good reference for designing the high-functionalized MON to capture contaminants and address environmental and agro-food safety issues.