Nanostructured metal–organic frameworks, TMU-4, TMU-5, and TMU-6, as novel adsorbents for solid phase microextraction of polycyclic aromatic hydrocarbons†
In the current study, three zinc(II) based metal–organic frameworks with different ligands, namely, TMU-4, TMU-5, and TMU-6, were prepared and coated onto the surface of stainless steel (SS) wire. Their applications were evaluated for the headspace solid phase microextraction (HS-SPME) of polycyclic aromatic hydrocarbons (PAHs) from water and soil samples. Due to the large surface area and unique porous structure of the MOFs as well as hydrophobic effects and π–π stacking interactions between the analytes and the MOF ligands, the prepared coated fibers showed a high affinity towards the PAHs. Among the three MOF coatings, the TMU-6 was the best candidate for the preconcentration of the PAHs. The TMU-6 coated fiber exhibited a long lifetime and high reusability for the analysis of PAHs; a single fiber could be used for about 60 consecutive extraction/desorption cycles without any significant loss of its extraction performance. Under the optimized conditions, low limits of detection (0.005–0.008 μg L−1) and a wide linear range (0.02–50 μg L−1) were obtained for the determination of PAHs in aqueous samples. Finally, the method was applied to the trace analysis of the PAHs in river water, hookah water, and soil samples, and relative recoveries in the range of 89–105% with relative standard deviations (RSDs) ranging from 5.3% to 9.6% (n = 3) were obtained. Single fiber repeatability and fiber-to-fiber reproducibility values expressed as RSDs were in the ranges of 5.9–7.9% and 8.6–10.4%, respectively.