A Surface‐Initiated Polymerized Microporous Organic Network Film for Efficient Extraction of Okadaic Acid From Seafood

Okadaic acid is a fatty acid polyether biotoxin that poses a significant threat to global human health. In this work, a type of heterogeneous microporous organic network films was synthesized using a surface-initiated polymerization method, which was employed to control the growth of microporous organic network onto the bromine-functionalized surface of a polymer film. The resulting microporous organic network films feature a porous structure, a strong hydrophobic surface, excellent chemical stability, a large specific surface area, and abundant adsorption sites. These films were then applied in film-based solid-phase extraction, and showed outstanding extraction performance for okadaic acid. Under optimized conditions, the film-based solid-phase extraction method was combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to establish a new analytical method with high sensitivity and efficiency. The developed method offers a wide linear range (2.0-1000.0 pg mL^-1) with good linearity (r ≥ 0.9998), a low detection limit (0.5 pg mL^-1), and high precision (RSDs ≤ 5.2%, n = 5). This method was further utilized for the determination of okadaic acid in seafood, successfully detecting trace levels of okadaic acid (5.4 and 13.9 pg mL^-1) with satisfactory recoveries (85.4%-105.8%). The results indicate that the microporous organic network films hold great application potential in sample pretreatment, and provide a novel synthesis strategy for microporous organic network films.