Determination of benzene homologuesin environmental water samplesby hollow-fiber liquid membrane-protected solid-phase microextraction based on Aluminum based metal-organic framework-polymer monolith fiber

A new rapid, simple and effective cleanup procedure is demonstrated for the determination of benzene homologues (Benzene, toluene, chlorobenzene, ethylbenzene, trimethylbenzene, styrene, and p-xylene) in water samples by using hollow-fiber liquid membrane-protected solid-phase microextraction (HFLM-SPME) based aluminum terephthalate metal-organic framework (MIL-53(Al) incorporated capillary monolithic fiber and gas chromatography–flame ionization detector (GC–FID). Main aim this study is fabrication of a novel aluminum terephthalate metal-organic framework (MIL-53(Al)) incorporated capillary monolithic fiber via polymerization for the extraction of benzene homologues in water samples. In this technique, a MIL-53(Al) incorporated monolith fiber was protected with a length of porous polypropylene hollow fiber membrane which was filled with water-immiscible organic phase. Subsequently the whole device was immersed into water sample for extraction. Methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA) and azo (bis)-iso butyronitrile (AIBN) was used as functional monomer, cross-linker and initiator respectively to prepare the MIL-53(Al) incorporated monolith fiber. The Al-MOF-polymer was characterized using fourier transform infrared (FTIR) spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and SEM-energy-dispersive x-ray spectroscopy (SEM-EDS) to clarify the crystalline structure retained as well as the homogeneous dispersion of Al-MOF (MIL-53) in polymer monolith. The developed Al-MOF-polymer (MIL-53) monolithic fiber was evaluated according to its extraction recovery of benzene homologues. Several parameters affecting the extraction recoveries of benzene homologues using fabricated Al-MOF polymer (MIL-53) monolithic fiber including desorption temperature and time, organic solvent, volume organic solvent, sample solution pH, ionic strength ,extraction time and stirring rate were investigated and optimized. Under the optimal conditions, the method detection limits (S/N = 3) were in the range of 0.03–0.07 ng mL−1 and the limits of quantification (S/N = 10) between 0.08 and 0.15 ng mL−1. Relative standard deviations for intra-day and inter-day precisions were 4.8–9.0% and 4.9–8.1%, respectively. Subsequently, this procedure was successfully applied with satisfactory results to the determination six benzene homologues in waters samples. The relative mean recoveries of in waters samples ranged from 92.0% to 101.0%.