The Electrical Preparation Of Carbon-doped Polythiophene Coatings And Application In Solid Phase Microextraction

Polycyclic aromatic hydrocarbons(PAHs)comprising two or more fused benzene rings would be produced as long as the organic materials are exposed to high temperature under hypoxic or anaerobic conditions.PAHs exist in aqueous,air and solid samples,and they are considered as main environmental pollutants because of their properties of toxicity,mutagenicity and carcinogenicity.People exposed to PAHs directly or indirectly will result in higher rates of DNA adducts and carcinogenesis.The transfer of PAHs from food contact materials into food is a direct way for human exposure to PAHs.Another nonnegligible way for humans to contact PAHs is that PAHs can biomagnify in the food chain through bioaccumulation.PAHs can be concentrated in soil and transfer from soil to water or farming products,thus entering the food chain.The determination of the migration of food contact materials and the PAHs in soil needs cumbersome preprocessing because of their low concentration and complex substrates.Hence,searching for a simple,fast and effective sample pretreatment has always been an important issue for the determination of PAHs.Integrating sampling,sample purification and preconcentration,head space solid-phase microextraction(HS-SPME)is widely used because the operation is simple and the coating is not easily damaged and smeared.Poly(3,4-ethylenedioxythiophene)(PEDOT)derived from polythiophene containing a conjugated bond system has an uniform film formation,low oxidation potential and good conductivity,which has drown much attention.Carbon materials are one of the most popular materials for SPME because of its large specific area,high electrical conductivity and good thermal stability.The focus of this work is to prepare carbon/PEDOT composite coating on stainless steel wire,which is used as adsorbent for HS-SPME,and combined with gas chromatography to analyze the PAHs of soil and the migration of food contact materials.Details are as follows:1.The MWCNTs/Mn O₂/PEDOT nanocomposite coating was prepared by sequentially depositing multi-walled carbon nanotubes(MWCNTs),manganese dioxide(Mn O₂)and PEDOT on stainless steel wire.By coupling with gas chromatography(GC),the coating was applied to the determination of PAHs.The effects of preparation conditions such as deposition time,number of deposition cycles and scanning speed on the extraction of coatings were investigated.The coating was characterized by thermogravimetry,scanning electron microscopy and X-ray photoelectron spectroscopy.The extraction conditions such as extraction temperature,extraction time,stirring speed and ionic strength of the coating were optimized.The extraction efficiency of MWCNTs/Mn O₂/PEDOT composite coatings is nearly 100 times higher than that of pure PEDOT coatings and nearly 20%higher than MWCNTs/PEDOT coatings.The proposed HS-SPME-GC-FID analysis method with good linearity and low detection limit has been successfully applied in the determination of polycyclic aromatic hydrocarbons in real soil samples.2.EDOT-GO was synthesized by a reflux technique,and PEDOT-GO polymer fiber coating was prepared on the surface of stainless steel wire by electrodeposition.The coating was applied to headspace solid phase microextraction(HS-SPME)and combined with gas chromatography(GC)for the detection of PAHs.The influences of preparation conditions,such as the ratio of EDOT to GO,the type of acid,and the number of deposition cycles were investigated.The coating was characterized by thermogravimetry,scanning electron microscopy and UV-visible spectroscopy.The extraction conditions,such as extraction temperature,extraction time,stirring speed and ionic strength were optimized.The proposed HS-SPME-GC-FID method was applied to detect the migration of PAHs in food packaging materials.