| The content of pollutants to be tested in environmental water samples is relatively low and the sample matrix is complex.Sample pretreatment has become a key part of analysis.Solid phase microextraction is a sample pretreatment technology that integrates extraction,separation and enrichment.The emergence of solid phase microextraction in the tube has broadened the application range of solid phase microextraction and can achieve higher extraction capacity and accuracy.Fiber in-tube solid phase microextraction is a unique form of tube solid phase microextraction.It has the obvious advantages of large coating area,high extraction efficiency,and easier use with analytical instruments.However,the limited types of coatings and the complicated preparation process are the main factors restricting the in fiber in-tube solid phase microextraction.In this paper,aramid fiber and polytetrafluoroethylene fiber are used as basic materials,and their application in fiber in-tube solid phase microextraction is studied.They are simply processed to prepare an in-tube solid-phase micro-extraction device,which is combined with liquid chromatography to realize online enrichment and analysis of environmental estrogens that are common in the environment.The main contents are as follows:1.The aramid fiber is directly filled into the stainless steel tube to coupled with HPLC for in-tube solid phase microextraction.The surface of aramid fiber was characterized by scanning electron microscope.The extraction performance of the solid phase microextraction tube for five environmental estrogens was investigated.The sample volume,extraction sampling rate,NaCl content and desorption time were optimized.Under the optimized conditions,an online analytical method with a wide linear range(0.2-20 μg/L)and low detection limit(0.016-0.13 μg/L)was established.The relative standard deviations of intra-day and inter-day reproducibility were less than 4.8%and 8.8%,respectively,which proved that the extraction reproducibility was good.The enrichment factor reaches 93-811,indicating that the aramid fiber has a certain extraction capacity.2.The aramid fiber is carbonized by a simple method to improve the extraction efficiency.The surface structure,chemical composition and graphitization degree of the fibers before and after carbonization were measured and characterized by scanning electron microscopy,X-ray photoelectron spectroscopy and Raman spectroscopy.They were filled in a stainless steel tube,combined with HPLCto investigated five environmental estrogens.Under the best conditions,the linear range of each substance was 0.5-10.0 μg/L,the detection limit was 0.011-0.13 μg/L,and the RSDs of extraction reproducibility is less than 4.8%.It is successfully applied to the actual sample.It was detected that the concentration of bisphenol A released from the polycarbonate bottle was 8.3 μg/L.3.After simple chemical treatment,the PTFE fiber was filled into a stainless steel tube.The surface of the material was characterized by scanning electron microscope and contact angle measuring instrument.A fully automatic,simple and sensitive online analysis method was developed to determine five estrogens.The correlation coefficient of bisphenol A in the linear range of 0.02-20.0 μg/L is 0.9933,the linear range of the other four estrogens is 0.05-20.0μg/L,and the correlation coefficient is 0.9989 to 0.9994.LODs(S/N=3)and LOQs(S/N=10)were in the range of 0.028-0.98 μg/L and 0.092-0.12μg/L,respectively.The RSDs of intra-day and inter-day were less than 0.2%and 3.4%,respectively,and the enrichment multiples for the five estrogens reached 1549-2260.Finally,the bisphenol A released from the polycarbonate bottle was quantitatively detected at a concentration of 5.86μg/L. |
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