Covalent organic framework/layered double hydroxide composite–coated poly(ether ether ketone) jacket for stir bar sorptive extraction of Sudan dyes

A novel coating for stir bar sorptive extraction was developed by growing a covalent organic framework, TpPa‐1 (derived from phenylenediamine and 1,3,5‐trimethylphloroglucinol), onto the surface of Ni‐Al layered double hydroxide. Using a poly(ether ether ketone) tube as the supporting substrate, a TpPa‐1/layered double hydroxide–coated stir bar was fabricated and demonstrated excellent extraction performance for Sudan dyes. Notably, its extraction efficiency significantly exceeded that of stir bars modified with only TpPa‐1 or Ni‐Al layered double hydroxide. Based on this innovative coating, a stir bar sorptive extraction‐high performance liquid chromatography method was established. This method exhibited low limits of detection (0.04–0.08 ng/mL) for the analysis of Sudan dyes. It also featured a wide linear range (0.25–100 or 200 ng/mL) and demonstrated good repeatability with relative standard deviations ≤6.22%. The recoveries obtained for spiked lake water and chili powder samples were 93.5%–105.2% and 87.8%–100.6%, respectively, demonstrating the practical potential of the developed method for detecting trace Sudan dyes in real samples.