Development of solid-phase microextraction fibers based on hybrid MIL-68(Fe)@MIL-101(Fe) for the analysis of polycyclic aromatic hydrocarbons in surface waters

The development of solid-phase microextraction fibers (SPME) using a MOF-based hybrid material as sorbent is presented. Even though different metal–organic frameworks (MOFs) have been reported as extractant phases, it is the first time that a hybrid material consisting of two iron-based MOFs is used with this purpose. In this work, the synthesis and characterization of the hybrid MIL-68(Fe)@MIL-101(Fe), as well as, the construction and characterization of the SPME fibers, is detailed. The assessment of its analytical performance, was studied by analyzing five polycyclic aromatic hydrocarbons (PAHs) in aqueous solution by means of gas chromatography coupled to flame ionization and mass spectrometry detectors. The developed analytical method exhibited detection limits between 3 to 10 μg·L⁻¹, good linearity (R² > 0.96) and remarkable intra-day (average RSD%=10) and inter-day (average RSD% = 14) precision. Moreover, enrichment factors ranged from 187 to 273-fold while accuracies (expressed as percentage recoveries) ranged from 64 to 111 %, and 84 to 123 % for low and high concentration levels, respectively. The developed method was successfully applied to the determination and quantification of PAHs in surface water samples, collected from two streams located in La Plata (Buenos Aires Province, Argentina).