A green aloeemodin-based covalent organic polymer as SPME coating for efficient enrichment of organochlorine pesticides in aquatic products.

Organochlorine pesticides (OCPs) are persistent organic pollutants, and detecting them at trace-levels in complex aquatic products remains challenging. Herein, a novel natural product derived covalent organic polymer was synthesized via a mild diazo-coupling reaction between aloeemodin and 4,4'-diaminodiphenylmethane. As a solid phase microextraction (SPME) coating, it exhibited excellent adsorption affinity for OCPs due to multiple interactions (hydrogen bonding, π-π stacking, and halogen bonding), which was confirmed by density functional theory calculations, X-ray photoelectron spectroscopy and Hirshfeld partition-based independent gradient model analyses. Coupled with gas chromatography-mass spectrometry, a reliable method was developed and validated for trace OCPs quantification in aquatic products (carp, grass carp, basa fish, cod, shrimp, and clam). Under optimized conditions, low limits of detection (0.005-0.50 ng g-1, S/N = 3), dependent on analytes and matrices, and satisfactory recoveries (92.5%-110%, RSDs ≤ 9.6%) were obtained. This work presents a sensitive analytical method for OCPs determination in aquatic products.