Trifluoroacetic acid modified MOF-808 composite coating for solid-phase microextraction of six phenols followed by gas chromatography analysis

The development of adsorption materials with good stability and high efficiency is significant in solid-phase microextraction (SPME). In this work, metal–organic framework MOF-808 (Zr) was modified by trifluoroacetic acid (TFA) to improve its hydrophobicity. MOF-808-TFA was electrochemically deposited on stainless steel wire with poly (3, 4-ethylenedioxthiophene) (PEDOT) to increase its extraction efficiency. The main parameters in the synthesis and extraction procedure were optimized. The prepared MOF-808-TFA@PEDOT nanocomposite coating was characterized by scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, Fourier transform infrared spectrometry and thermogravimetric analysis. A direct immersion solid-phase microextraction (DI-SPME) method for six phenols was developed based on the nanocomposite coating which had good service life (150 times). The extraction efficiency was 12 times higher than the commercial PDMS coating. Combined with gas chromatography-flame ionization detector (GC-FID), a simultaneous determination method for the six phenols was established, which exhibited wide linear range with 0.05–50 μg L⁻¹ (R² > 0.99). The limit of detection was 0.01–0.08 μg L⁻¹ (S/N = 3), and the limit of quantification was 0.05–0.25 μg L⁻¹. The method was applied to determine the migration quantity of phenols from four metal cans with recovery rate between 85.6–116.8 % (RSD < 13.9 %), and it was verified by standard GC–MS method and SPSS statistical analysis. These results indicated the DI-SPME-GC-FID method had reliability and potential application in security testing for food contact materials.