Thiol-Yne Click Postsynthesis of a Sulfonate Group-Enriched Magnetic Microporous Organic Network for Efficient Extraction of Benzimidazole Fungicides

The lack of functional groups or binding sites largely hindered the broad application of microporous organic networks (MONs). Herein, we report the fabrication of the sulfonate group-enriched magnetic MON composite (MMON-SO3H@SO3Na) via the combination of the sulfonic acid group containing the monomer and thiol-yne click postmodification for efficient magnetic solid-phase extraction (MSPE) of benzimidazole fungicides (BZDs) from complex sample matrices. The well-defined core-shell-structured MMON-SO3H@SO3Na was obtained and served as an advanced adsorbent for MSPE for concentrating and monitoring trace BZDs. The MMON-SO3H@SO3Na with numerous sulfonate groups provides plenty of ion-exchange, hydrogen-bonding, and p-p sites, leading to the favorable affinity to BZDs via multiple interaction mechanisms. The MMON-SO3H@SO3Na-based MSPE-high-performance liquid chromatography method afforded a wide linear range, low limits of detection, large enrichment factors, good precisions, and reusability for BZDs. Trace BZDs in complex vegetables and fruit samples were successfully detected by the established method. The MMON-SO3H@SO3Na also exhibited good selectivity toward multiple types of polar contaminants containing hydrogen-bonding sites and aromatic structures. This work provided a new postsynthesis strategy for constructing novel and multifunctioned magnetic MONs for preconcentration of trace analytes in a complex matrix.