| Solid-phase microextraction (SPME) is a novel solvent-free extraction technique thatintegrates extraction, concentration and sample introduction in a single step. It is simple,convenient, rapid and highly sensitive. Therefore, SPME has been successfully applied topreconcentration and determination of various analytes from different matrixes involvedenvironmental, foods, biological and pharmaceutical samples coupled to gas chromatography(GC), high performance liquid chromatography (HPLC) or capillary electrophoresis (CE).The fiber coating is its active site contacting analytes of interest. The property of the coatingdetermines the extraction capacity, sensitivity, selectivity and analytical results. For thesereasons, the hot issues of SPME are currently concentrated on the investigation of novel fibercoatings to improve the extraction efficiency and extend the applications of SPME. With thedevelopment of these novel coatings, SPME has found a wide applications in extraction andseparation. The fiber coating is the key factor of SPME because the extraction performanceprimarily depends on the coating properties. Currently, the general applications for SPME aredevoted to fused silica fibers coated with various polymeric coatings although thesecommercial coating could meet with the requirement for extraction. However, they possesssuch disadvantages as short lifetime, low thermal stablility, swelling in organic solvent, littleselectivity for general-purpose polymers. Meanwhile most of them are expensive. As a result,new fiber coatings with high stablility, high mechanical strength and good selectivity areneeded to prepare and investigate in order to improve the extraction behavior of SPME,extend their applications and prolong the lifetime of the fiber coating. It is of great importanceto develop novel fiber coatings for special demand in SPME.Bisphenol A (BPA) is widely used in the production of polycarbonate plastics and epoxyresin. There is plenty of evidence that many consumer products contain and release BPA. Inrecent years, in order to assess the health risks of BPA exposure and related health concern,much attention has been paid to improving the sensitivity and accurate determination of BPAin aquatic environment, food and biological media. Since the real sample is a complex matrix,and the concentration of BPA was reported in micrograms per milliliter, the detection method must have certain selectivity and high sensitivity. So far, researchers have successfullyanalyzed quantitative and qualitative of BPA. However, only a few studies dealt with thepreparation of PANI-SPME fiber in sulfuric acid used for detection of BPA.Since the PANI films, made with electrochemical methods, have been used in SPME ofphenol and4-chlorine phenol in sewage, the study and application of PANI-SPME becomepopular. Currently, it has been used in the highly efficient extraction of aromatic amines,polycyclic aromatic hydrocarbons, fatty alcohols, phenolic compounds, polychlorinatedbiphenyls, phthalate esters and benzene series. In the previous studies, solid phase coating andwire were combined by chemical bond when electrochemically deposited. Thus it had higherphysical stablility than commercial fiber. The stainless steel wire was etched withhydrofluoric acid before it was electrodeposited. The substrate surface becomes rough andporous and chemical etching could make the PANI coating firm and increase the specificsurface area of PANI coating. Also, the dense net structure and large specific surface areadetermined that the novel PANI had more absorption capacity and quicker extraction balancefor BPA than conventional commercial fiber. PANI, a conductive macromolecule, has largeconjugate π-π structure. Therefore it has a strong thermostablility and anti-solubility. Itsextraction efficiency won’t be affected with the repeated use and long-time use. As to thepollutant analysis, this new PANI-SPME fiber can adsorb and separate the organic pollutantwith polarity, non-polarity, volatility and non-volatility. Because of its conjugated π-πstructure, PANI could be adsorbed BPA via hydrogen bonding and electrostatic interactionbeyond the limit of like dissolves like.The thesis consists of four parts:Chapter1, The environmental pollution and effect of bisphenol A, chlorophenolcompounds and benzopyrene are introduced in life. The applications of SPME and newresearch progress of SPME coating are reviewed.Chapter2, The substrate in the study was chemically etched stainless steel wire. SPMEfiber with polyaniline (PANI) coating and HPLC were combined to measure BPA in waterand drink samples. The experiment conditions such as extraction time, desorption time,extraction temperature and salting-out effect were optimized The SPME-HPLC method was esTablelished to measure the trace amount of BPA in liquid samples. The prepared SPMEfiber with electrodeposition has high mechanical strength, long service time, good stablility,low production cost, high efficiency and sensitivity.Chapter3, Porous polyaniline (PANI) coatings doped with different counter ions wereprepared onto the surface of stainless steel wires using controlled potentiostatic coulometry.The results demonstrated that the PANI coating with perchlorate dopant (PANI-ClO4)exhibited the greatest extraction efficiency of Chlorophenols (CPs), indicating that theextraction capability could be modified by introducing different counter ions into the PANIcoatings.Chapter4, A novel metal fiber for SPME was developed for the determination of traceBenzo[a]pyrene (B[a]p) in environmental water samples using an anodic oxidation ofstainless steel wire coupled with HPLC. Several important parameters influencing theextraction efficiency of B[a]p were investigated and optimized. The SPME-HPLC methodwas establelished to concentration and determination of B[a]p in environmental watersamples. The proposed method has good precision and satisfactory recovery. |
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