Preparation And Extraction Application Of Polyimide Porous Microspheres

Solid phase extraction(SPE)and solid-phase microextraction(SPME)are two most used sample preparation technologies.Polyimide(PI)is a widely used special functional polymer.Because of its high temperature resistance,chemical resistance,good mechanical strength properties,it is widely used in aerospace,fuel cells,electronic equipment,military equipment,and many other industries.In this thesis,porous PI particles and microspheres were prepared,and were successfully applied to the high-efficient extraction and quantitative detection of organic pollution and drug residues in environmental water samples,condiments,and food.There are four chapters in this thesis.The first chapter is the introduction.The basic theory,the main forms of SPE and SPME,the types of extraction materials,and the preparation methods are briefly introduced.Finally,the research ideas and main work of this paper are summarized.In chapter two,PI microparticles were prepared in batches by aerosol spray-precipitation phase transformation method.The surface of the particles had 10-60 nm open pores and a specific surface area of 52 m~2/g.The 250-500μm flake particles were screened and used as the extraction phase of Bar adsorptive microextraction(BAμE)Combined with thermal desorption and gas chromatography-mass spectrometry(TD/GC-MS),Parabens in condiments were determined rapidly.This method has low detection limit(0.005-0.008μg/L),good correlation coefficient,and high enrichment factor.PI particle microextraction rods are very reproducible and can be reused more than 50 times.Compared with conventional PI phase change microextraction rods,the absolute recovery of parabens is increased by 1.9 to 2.7 times.Common condiments like soy sauce,vinegar and cooking wine were tested,and the relative recovery rate is 86.1%-109.0%.It is proved that this method is suitable for the rapid detection of parabens in condiments.In chapter 3,the same method as in Chapter 2 was adopted to prepare PI porous particles in batches,in which 50-75μm spherical microsphereswere sieved out,and were used directly as solid phase extraction adsorbents.Combined with ultra-efficient liquid chromatography-fluorescence detection,fluoroquinolones from water and food samples were extracted and quantitated.The SPE with porous PI microbeads exbibited the good selectivity,and removed most matrix interferences The method has a high extraction capacity(19 L/g),low detection limits(0.002-0.011μg/L for water,0.12-5.54μg/L for eggs and milk).Porous PI microspheres have been successfully demonstrated as one kind of excellent SPE adsorbents for for the high-efficient extraction of fluoroquinolones in environmental water and food samples.In Chapter 4,polyamic acid(PAA)was used as a precursor to prepare layered PI nanosheet microspheres via self-assembling and amidatation by solvothermal method.The microspheres have a larger specific surface area.PI nanosheet microspheres were also used as the extraction phase of BAμE,and then used in series with TD/GC-MS for the quantitative analysis of nitroaromatic compounds in environmental water samples.A wide linear range(0.05-20μg/L or 0.05-50μg/L),high enrichment factor(528-1410),and low detection limit(0.005-0.013μg/L)are obtained.When applied to the analysis of actual water samples,the relative recovery is 72.2-122.6%and the relative standard deviation is between 0.1%and 10.5%,which provides a new method for the quantitative detection of aromatic compounds in environmental water samples.In Chapter 5,brief conclusions and prospects for the research work of this thesis were proposed.