Polydopamine-based immobilization of a hydrazone covalent organic framework for headspace solid-phase microextraction of pyrethroids in vegetables and fruits

• Synthesis of a novel hydrazone covalent organic framework with a simple method.
• Application of the fiber to preconcentration of pyrethroids combined with GC-ECD.
• Optimization of synthesis and preconcentration processes.
• Validation of the method and application to real sample analysis.

We designed a novel hydrazone covalent organic framework (COF) and developed a polydopamine (PDA) method to immobilize COF on a stainless steel fiber for headspace solid-phase microextraction (HS-SPME). A series of characterization studies was performed to validate the structure and property of the prepared fiber. The COF-PDA fiber was applied for the extraction of pyrethroids coupled with gas chromatography equipped with an electron capture detector (GC-ECD). Under the optimum experimental conditions, high enhancement factors of 307–2327 were achieved, indicating that the hydrazone COF possessed good extraction efficiency for pyrethroids. The detection limits ranged from 0.11 to 0.23 μg kg−1 with relative standard deviations varying in the range of 3.6–9.2% (intra-batch) and 6.9–12.1% (inter-batch), respectively. The developed method was applied to the determination of pyrethroids in fruit and vegetable samples and the accuracy was assessed through recovery experiments.