Fabrication and evaluation of a fluorophilic adsorbent for multiple monolithic fiber solid-phase microextraction of fluorobenzenes

A new type of highly fluorinated monolith (HFM) was fabricated and used as adsorbent of multiple monolithic fiber solid-phase microextraction (MMF-SPME). To prepare the HFM, a fluorinated monomer, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate was in situ copolymerized with dual cross-linkers (divinylbenzene and ethylenedimethacrylate). The fabrication parameters including the content of monomer and porogenic solvent in the polymerization mixture were optimized to obtain expected extraction performance and life span. The physicochemical properties of the HFM were systematically investigated with elemental analysis, infrared spectroscopy, scanning electron microscopy and mercury intrusion porosimetry. The effective extraction of six fluorobenzenes was selected as a paradigm to demonstrate the fluorophilic characteristic of HFM/MMF-SPME. At the same time, a convenient and effective method for the determination of trace fluorobenzenes in environmental water samples was developed by coupling HFM/MMF-SPME with high performance liquid chromatography/diode array detection (HFM/MMF-SPME-HPLC/DAD). Results indicated that the limits of detection (S/N = 3) for targeted compounds were in the range of 1.09-5.88 μg/L. The intra-day and inter-day precision (relative standard deviations, n = 4, %) at two spiked concentrations were 4.2-10.6% and 6.1-10.8%, respectively. Finally, the developed method was successfully applied to the analysis of fluorobenzenes in spiked real water samples with satisfactory recoveries and repeatability.