| Solid phase microextraction (SPME) is a new sample pretreatment technique. It has attracted much attention because of its high efficiency, low solvent consumption, and easy combination with other instruments. Although some commercial coatings are available now for pretreatment of samples, they show some shortcomings such as low extraction efficiency and low stability. As the coatings determine the stability, selectivity and extraction efficiency of SPME, the preparation of new coatings suitable for different analtyes is very important.Polyaniline (PANI) prepared by electrochemical method generally has large specific surface and high extraction capacity, so it is a good material for constructing SPME coatings. But its stability is not high enough and its suitable objects are limited. Ionic liquids (ILs), known as molten salts, are a class of nonmolecular solvents. They have been widely used in separation and analysis due to their advantages of non-flammable, non-volatile and stable etc. Therefore, by combining with ILs the resulting PANI based composite coatings should show improved performance. Thus they can be more widely applied in environment and food analysis, etc.In this dissertation, a systemic study on the electrochemical fabrication and application of IL-PANI based SPME coatings is carried out. The main content and results are as follows:1. A hydrophobic ionic liquid was coated on a stainless steel wire, then polyaniline was electrodeposited on it to fabricate a IL-PANI composite coating. The coating showed net-like structure, having large specific space and high adsorption capacity for phenol derivatives. By coupling with GC the phenol derivatives were determined, and it showed good performance. Compared with PANI coating, the IL-PANI coating had higher extraction efficiency and thermal stability. The developed method was successfully applied to the determination of phenol derivatives in environmental water samples.2. PANI-supported ionic liquid coatings were fabricated by two-steps. The PANI was electrodeposited on stainless steel wires, then IL was coated on it. The influence of IL and other conditions were explored and the extraction ability of the resulting coatings for different analytes (i.e. benzols, aryl halide, alcohols, phenols and amines) was compared. For the determination of fatty alcohols in drinks a suitable coating was selected. By Coupling with GC, the proposed method presented high sensitivity, low detection limits and good repeatability. In addition, the coating showed good durability.3. An acidic ionic liquid (i.e 1-sulfobutyl-3-methylimidazolium hydrosulfate) was used as supporting electrolyte and dopant, and a novel proton-type ionic liquid doped polyaniline (HIL-doped PANI) coating was prepared. The HIL-doped PANI coating showed granular nanostructure and had large specific surface. When it was applied to the headspace solid-phase microextraction of several amines, it showed high extraction efficiency. The enrichment factors were 191.8-343.9 for different amines, much higher than those of common PANI and commercial polydimethylsiloxane/divinylbenzene coatings.4. By shrinking reaction, multi-walled carbon nanotube (MWCNT) was functionalized with ionic liquid 1-(3-aminopropyl)-3-methylimidazolium bromide. Then the resulting MWCNT@IL was doped into the electrodeposited polyaniline to prepare an MWCNT@IL/PANI coating. The MWCNT@IL showed good dispersity in polyaniline. The enrichment capability of the coating was investigated for amine, benzene, fatty alcohols, polycyclic aromatic hydrocarbon, phenols and benzoic acid ester compounds. Among them it showed high selectivity and extraction efficiency for benzoic acid ester compounds. Through coupling with GC a method was developed for the determination of benzoic acid ester compounds. The method presented high sensitivity and low detection limit (1.5-6.1 ng/L). This work expanded the application range of ionic liquids in solid-phase microextraction.5. A novel nanostructured polyaniline-poly (propylene oxide) (PANI-PPO) composite coating was electrochemically synthesized on a stainless steel wire, by using acidic ionic liquid 1-sulfobutyl-3-methylimidazolium hydrosulfate as supporting electrolyte. The coating showed good hydrophobicity and allowed for the direct immersion solid-phase microextraction (DI-SPME) in complex matrices and gas chromatographic analysis of poorly-volatile carbamate pesticides. The practical feasibility of the method was evaluated by measuring carbamate pesticides in vegetable samples. This technology provided a new way for the preparation of hydrophobic coating.6. A novel polyaniline-poly(m-aminobenzoic acid)-IL composite coating was prepared for the head-space solid phase microextraction (HS-SPME) of aryl halides. The coating showed high mechanical stability, thermal stability (up to 330?) and durability (repetitively used for more than 120 times). In addition, the coating had good chemical stability, it could tolerate organic solvents, alkali and acid to some extent. The coating was applied to the determination of real samples. |
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