Novel Matarials Coupled With Solid Phase Extraction Pretreatment Technique For Separation And Detection Of Polar Organic Pollutants In Food Samples

Wide varieties of polar organic pollutants are common contaminants in water and food,and water is a kind of solvent with high polarity,so these polar compounds are very hydrophilic due to the principle of"like dissolves like".As a result,it is difficult for these polar compounds to be adsorbed and detected in water and food.These polar compounds are highly toxic and can be enriched in the food chain or enter the human body through skin contact,etc.,thereby endangering human health.And because of their low concentration in food and water samples as well as the matrix effects,they are very difficult to detect.Trace analysis and detection of polar organics in water and food samples has been given rise to wide concern of the public in the field of food safety.In this study,three emerging functional materials were used:bamboo charcoal,Zr-based metal organic framework material PCN-224 and magnetic covalent organic framework material Fe₃O₄@COFs,which were used as solid phase extraction packing materials and magnetic solid phase extraction adsorbents,respectively.A new method for the determination of perfluorinated compounds,sulfonamides and phenolic endocrine disruptors in water and food samples was established,and different environmental water samples,drinking water and food samples were analyzed to verify the applicability and precision of the method.Possible adsorption mechanisms of different materials for the target pollutants were explored.The main results of this paper are as follows:1.Bamboo charcoal was used as solid-phase extraction adsorbent for the enrichment of six perfluoroalkyl acids（PFAAs）in environmental water samples before liquid chromatography–tandem mass spectrometry analysis.The specific porous structure,high specific surface area,high porosity,and stability of bamboo charcoal were characterized.Several experimental parameters which considerably affect extraction efficiency were investigated and optimized in detail.The experimental data exhibited low limits of detection（LODs）(0.01-1.15 ng·L^-1),wide linear range（2-3 orders of magnitude and R≥0.993）within the concentration range of 0.1-1000 ng·L^-1,and good repeatability（2.7-5.0%,n=5 intraday and 4.8-8.3%,n=5 interday）and reproducibility（5.3-8.0%,n=3）.Bamboo charcoal was successfully used for the enrichment and determination of PFAAs in real environmental water samples.The bamboo charcoal-based solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry analysis possessed great potential in the determination of trace PFAA levels in environmental water samples.2.A porphyrinic metal–organic framework（PCN-224）was fabricated and used as an adsorbent for solid-phase extraction of ultratrace levels of polar sulfonamide antibiotics from food and drinking waters.The PCN-224 was characterized by scanning electron microscopy,Fourier transform infrared spectroscopy,and powder X-ray diffraction analyses.Parameters affecting the extraction efficiency were optimized.The sulfonamides were quantified by liquid chromatography-tandem mass spectrometry.Figures of merit include（a）low limits of detection（0.07–0.47 ng·L-1）,（b）wide linear ranges（0.5–2000 ng·L-1）,and（c）good repeatabilities（2.8%–6.7%）and reproducibilities（1.7%–5.1%）.The method was successfully applied to the determination of sulfonamides in food and drinking water samples.3.A magnetic covalent organic framework（Fe₃O₄@COF）with core–shell structure was fabricated at room temperature and used as an adsorbent for magnetic solid-phase extraction of polar endocrine-disrupting phenols（4-n-nonylphenol,4-n-octylphenol,bisphenol A and bisphenol AF）.The sorbent was characterized by transmission electron microscopy,FTIR,powder X-ray diffraction and other techniques.The main parameters governing the extraction efficiency were optimized.The phenols were quantified by HPLC with fluorometric detection.The method has attractive features such as low limits of detection(0.08-0.21 ng·mL^-1),wide linear ranges(0.5-000 ng·mL^-1),and good repeatability（intra-day:0.39%–4.99%;inter-day:1.57%-5.21%）.Satisfactory results were obtained when the developed method was applied to determine the four target pollutants in real world drink samples with spiked recoveries over the range of 81.3¹18.0%.This indicates that the method is a powerful tool for the enrichment and determination of endocrine-disrupting phenols in drink samples.