Preparation And Application Of Polypyrrole Composite Solid Phase Microextraction Coating

A novel solvent-free solid-phase microextraction（SPME）technique was developed in 1990.The technique uses polymer-coated fused quartz fibers or stainless steel wires such as adsorbent materials to extract analytes from the sample matrix.It integrates sampling,extraction,enrichment,purification and sample into one step.The properties of fiber coatings have the greatest influence on extraction efficiency.However,the currently available SPME fibers show some drawbacks.For example,common silicon dioxide（Si O₂）based fiber is easy to break,the thermal stability of the coating is not enough and poor selectivity and so on.In order to overcome these shortcomings,many research groups prepared Covalent Organic Frameworks（COFs）,Metal Organic Frameworks（MOFs）,conducting polymers and their derivatives,molecularly imprinted materials and other new coatings.Polypyrrole conductive polymer has advantages of good stability,high conductivity and simple synthesis,etc.It is one of the most important and widely used conductive materials at present.At the same time,dipole-dipole,π-πand hydrogen bond can be produced between polypyrrole coating and other polar molecules.Therefore,it is suitable for extraction and enrichment of polar aromatic substances.In this work,pyrrole as the base extraction material,through doping modification to improve its extraction performance,the extraction head has a good extraction effect on aromatic substances,and used in the detection of environmental water,perfume and other samples.Specific research contents and results are as follows:1.Preparation of poly（pyrrole）solid phase microextraction coating doped with gold nanoparticles and barium coordination polymer and detection of nitro polycyclic aromatic hydrocarbonsPolypyrrole composite solid phase microextraction coating（Ppy-Au-Ba CP）doped with gold nanoparticles and barium coordination polymer was prepared by electrochemical deposition in aqueous solution of sodium dodecyl sulfate.At the same time,the concentration of dopant and the conditions of electropolymerization were optimized.The experimental results show that a large number of particles are attached to the surface of the composite coating,which is beneficial to the increase of its effective specific surface area.At the same time,the thermal stability of the composite is improved due to the doping of barium complex（>300℃）.The composite coating was combined with gas chromatography to detect five kinds of nitropolycyclic aromatic hydrocarbons（NPAHs）.Under the optimal conditions,the linear range of the composite coating is 10～3500 ng L^-1,and the detection limit is 0.92～4.16 ng L^-1（S/N=3）.The method has been applied to the detection of environmental water samples and satisfactory experimental results have also been obtained.2.Preparation of functionalized graphene and ionic liquid co-doped polypyrrole solid phase microextraction coating and determination of benzoate preservatives by gas chromatographyA novel composite coating of Ppy/Mn O₂-f Gr/[AVIm]NTf₂was prepared by doping functional graphene and ionic liquid modified by manganese dioxide into polypyrrole by cyclic voltammetry and deposited on the surface of stainless steel wire.Scanning electron microscopy（SEM）and thermogravimetric analysis（TGA）showed that the coating surface was rough and porous,with large specific surface area and good thermal stability（>400℃）.Combined with gas chromatography,it was used for the determination of four kinds of benzoic acid esters,the linear correlation is good（>0.9965）,with a linear range of 25 to 60,000 ng L^-1and a detection limit of 2.84to 6.42 ng L^-1（S/N=3）.Compared with commercial coating（PDMS）,the composite coating showed a certain extraction advantage.3.Preparation of porous boron nitride doped polypyrrole-2,3,3-trimethylindole coating and highly sensitive detection of polycyclic aromatic hydrocarbonsIn the electrochemical copolymerization of pyrrole and 2,3,3-trimethylindole,porous boron nitride（BN）was doped into them to prepare Ppy/P2,3,3-TMe@In/BN composite coatings,which exhibited all kinds of structures.The thermal stability test shows that the composite coating has good thermal stability（>320℃）.Under the optimal conditions,the composite coating was used for the determination of three kinds of polycyclic aromatic hydrocarbons（naphthalene,acenaphthene,fluorene）.It was found that the linear range of the composite coating was wide(1～80μg L^-1)and the detection limit was low(12.3～18.6 ng L^-1,S/N=3).It has been applied to the determination of polycyclic aromatic hydrocarbons in complex water samples by headspace solid phase microextraction and gas chromatography with good results.