Hydrophobic covalent organic frameworks for solid-phase microextraction of pyrethroids

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Pesticide residue analysis in food is crucial for public health.
• Developing sensitive and selective extraction materials is essential for accurate detection.
• Covalent Organic Frameworks (COFs) show potential as advanced sorbent materials.

Purpose of the Study:

• To synthesize and characterize novel hydrophobic COFs for pesticide extraction.
• To develop a Solid-Phase Microextraction (SPME) method for pyrethroid detection in tea.
• To evaluate the performance of COF-based SPME for food safety analysis.

Main Methods:

• Synthesis of benzotrithiophene (BTT)-based hydrophobic COFs (BTT-TAPA-COF and BTT-TAPB-COF).
• Coating COFs onto stainless-steel fibers for SPME applications.
• Coupling SPME with Gas Chromatography-Mass Spectrometry (GC-MS) for pyrethroid analysis.
• Optimization of SPME parameters, including direct immersion (DI-SPME) vs. headspace (HS-SPME) and adhesive selection.

Main Results:

• Synthesized COFs exhibited high porosity (up to 1531 m²/g) and strong hydrophobicity (contact angles > 118°).
• DI-SPME with COF-coated fibers achieved 200-fold higher extraction efficiency than HS-SPME.
• The developed method showed excellent linearity (R² > 0.9852), low limits of detection (LODs as low as 0.002 ng·L⁻¹), and good recoveries (81.1%–125.8%).
• Bifenthrin and λ-cyhalothrin were detected in tea samples at environmentally relevant concentrations.

Conclusions:

• Hydrophobic BTT-COFs are effective materials for high-performance SPME.
• The developed COF-based SPME-GC-MS method enables sensitive and reliable determination of pyrethroids in tea.
• This approach holds significant promise for routine food safety monitoring and pesticide residue analysis.