Amino‐Rich Microporous Organic Network Composite Membranes for Efficient Extraction of Domoic Acid From Complex Matrices

Microporous organic networks (MONs) have attracted considerable attention because of their high porosity, modifiable structure and excellent stability. However, their rigid structure makes it difficult to form membranes, leading to limited separation applications. MONs’ powder suffers from issues of dusting and severe aggregation, leading to difficulties in separation and recycling. Herein, MONs’ powder was converted into flexible and reusable membranes via phase inversion. The membranes were applied to enrich and extract domoic acid (DA, an algal toxin) from complex matrices. The adsorption performance and mechanism of three MONs membranes with different amino content were investigated and compared. The results indicate that the adsorption energy of the membranes for DA is positively correlated with the number of amino groups. Under optimized conditions, by combining syringe filter‐based membrane micro‐solid‐phase extraction (SF‐M‐µSPE), with high‐performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS), the developed method showed a low detection limit (0.5 pg mL −1 ), a wide linear range (1.5∼1000.0 pg mL −1 , R ≥ 0.9999) and good repeatability (RSD ≤ 3.8%, n = 6). The membranes were successfully used to extract DA from seafood. There was trace DA (9.4 pg mL −1 ) found in oyster samples. This work demonstrates the great potential of MONs membranes in sample pretreatment.