Determination of acylanilide fungicides in aquatic products using molecular imprinting solid-phase extraction combined with UPLC–MS/MS

Acylanilide fungicides are widely used in agricultural and aquaculture, so the determination of their residues is crucial for ensuring the quality and safety of agricultural products. In this work, a molecularly imprinted polymer (MIP) for the selective extraction of acylanilide fungicides was synthesized using oxadixyl as a dummy template, with methacrylic acid and acrylamide as functional monomers. The synthesis conditions were optimized, and the resulting MIP exhibited excellent adsorption capacity (Q ≥ 50.3 mg·g −1 ) and high selectivity (IF > 5.5). The morphology and structure of the MIP were characterized, and its adsorption performance and mechanism were investigated. After optimizing the molecularly imprinted solid-phase extraction (MISPE) procedure, an MISPE-UPLC–MS/MS method was developed for the determination of benalaxyl, furalaxyl, metalaxyl and its metabolite metalaxyl acid in aquatic products. The method demonstrated good linearity ( r  > 0.995), and limits of detection and quantification for the four analytes were 0.1–0.3 μg·kg −1 and 0.3–1.0 μg·kg −1 , respectively. Average recoveries of metalaxyl, metalaxyl acid, benalaxyl, and furalaxyl in six aquatic products (grass carp, snakehead, bullfrog, pond loach, dongfeng snail, and red swamp crayfish) were 95.2–103.4 %, 86.7–101.5 %, 94.6–103.7 %, and 92.7–106.9 %, respectively, with relative standard deviations below 11.2 %. This highly sensitive and selective method effectively eliminates matrix interferences from various complex samples, thereby offering a robust strategy for monitoring acylanilide fungicide residues.