In Situ Fabrication Of Nanostructured Ni Ti Solid-phase Microextraction Fibers And Their Applications In Environmental Analysis

Solid-phase microextraction?SPME?is an environment-friendly sample preparation technique.In SPME,the fiber consists of a supporting substrate and a sorbent.The mechanical stability of the fiber substrate greatly influence its durability.However,most commercially available SPME fibers are used with fused-silica fibers as substrates,which are easily broken,and the organic coating is easily peeled off.In this thesis,NiTi wires were empolyed as SPME fibers,and fabricated with different methods.The treated fibers were studied and used for the analysis of trace PAHs in environmental water samples.The advantages and disadvantages of the different preparation methods were described.This thesis mainly consists of four chapters:Chapter 1:The source and crisis of PAHs were briefly introduced.The principles and methods of SPME were reviewed in detail.Excellent properties and applications of metal nanomaterials in SPME were summarized.Chapter 2:PAHs in the water samples were enriched by annealing NiTi fibers coupled with HPLC-UV.Under the optimized conditions,the linear range of the analyte concentration was 0.2-300?g·L^-1.The linear correlation coefficient?R?was more than0.9990,the relative standard deviation was less than 9.36%.Ni Ti fibers have higher extraction efficiency and selectivity than other fibers,and they have been used more than300 times and can be successfully used for enrichment,separation and quantitative analysis of water samples in the Yellow River.Chapter 3:Porous nanostructured coating was successfully prepared by in situ oxidation on the surface of a Ni Ti wire for several times with H₂O₂.The optimized conditions for the extraction of Nap,Phe,Flu,Pyr,B[a]p in the water samples of the Yellow River in Lanzhou section were studied by using the coating coupled with HPLC.The linear range was between 0.1-400?g·L^-1.The relative standard deviations?RSDs?were less than 8.42%and the range of LODs was between 0.026-0.056?g·L^-1.The fiber surface exhibits large area and can be used for enriching PAHs in environmental water samples.Chapter 4:SPME fibers with nanostructured metal oxide as the coating were prepared by Fenton oxidation for the first time.The novel fiber was used for enrichment of PAHs in the environmental water samples coupled with HPLC under optimized extraction conditions.The linear range of the analyte concentration was 0.2-300?g·L^-1 and the linear correlation coefficient?R?was more than 0.9995.The range of LODs was between0.006-0.093?g·L^-1,and the average recovery was 97.64-105.5%.The RSD of repeatability for the same fiber ranged from 4.69 to 6.32%,and for different fibers was6.19 to 8.35%.In addition,the Ni Ti fiber prepared using this new method has excellent extraction selectivity for PAHs,long service life and simple operation,and can be used to replace the conventional quartz fiber in SPME.