Preparation And Applications Of Solid Phase Microextraction Fiber Coated With Single-walled Carbon Nanotubes

Solid-phase microextraction(SPME) has been widely applied in sampling and analysis of environmental samples due to its simplicity,solvent free nature and feature of easy coupling to GC and HPLC.However,the commercial SPME fibers present drawbacks such as relatively low operating temperature,instability and swelling in organic solvents,easy breakage,low extraction efficiency for polar compounds and stripping off of coating.The laboratory-made SPME fibers reported in literatures could only partially overcome the limitations of commercial SPME fibers.Further developments in SPME as a highly efficient extraction technique,will greatly depend on the breakthroughs of new SPME fibers.In this study,a novel SPME Pt fiber coated with single-walled carbon nanotubes(SWCNTs) was prepared for the first time by electrophoretic deposition (EPD) and applied to the determination of phenols and anilines in aqueous samples by direct immersion(DI)-SPME-HPLC-UV.The main experimental contents and results were summarized as follows:(1) Under optimized conditions,a SPME Pt fiber coated with SWCNTs was prepared by EPD.This technique was proved to be simple and reproducible.The obtained SWCNTs coating was uniform and dense,and possessed advantages such as high organic solvent stability,high mechanical strength and unbreakable.In addition, the novel fiber is conductive.(2) The prepared SWCNTs fiber was applied to the determination of 6 phenols,i.e., phenol,p-nitrophenol,m-methylphenol,bisphenol A,2-chlorophenol and 2,4-dichllorophenol,in aqueous samples by SPME-HPLC method.The results showed that the SWCNTs fiber was effective and superior to commercially PA fiber in extracting the studied phenols in aqueous sample.A durability of more than 80 analyses was achieved for one unique fiber.Under optimized conditions, the detection limits for the phenols varied between 0.9 and 3.8μg/L,the precisions were in the range of 0.7-3.2%(n=3),and linear ranges were within 10 and 300μg/L.(3) The prepared SWCNTs fiber was treated with H₂ at 550°C.The obtained fiber was used to determine 6 anilines,i.e.,p-nitroaniline,aniline,2,4-dinitroaniline, 2-chloroaniline,3,4-cichloroaniline,in aqueous samples by SPME-HPLC method.The results showed that the extraction efficiency of the fiber increased after the H₂ treatment.The treated SWCNTs fiber was superior to commercial PDMS/DVB fiber in extracting the studied anilines in aqueous sample.The extraction efficiency of the treated fiber for anilines kept constant after it was immersed in solutions with a pH of 1 or 13 for 2 h.The linear range,LODs and LOQs of the established method were 1.0-150.0μg/L(1.0-100.0μg/L for aniline),0.06～0.31μg/L and 0.27-1.05μg/L,respectively.