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The Nanocomposite Material-based Sorbents for Analysis of Environmental and Biological Samples

Roostaie, Ali | 2014

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 46675 (03)
  4. University: Sharif University Technology
  5. Department: Chemistry
  6. Advisor(s): Bagheri, Habib
  7. Abstract:
  8. This thesis contains two major sections. The first section is dealing with the preparation of conductive polymers-based sorbents while the second section is mostly focused on the synthesizing nanocomposites by electrospinning. All the prepared sorbents and nanofibers have been utilized to isolate some organic compounds in environmental and biological samples. Section I:In the first chapter, an unbreakable solid phase microextraction fiber coating based on aniline-silica nanocomposite was electrodeposited on a stainless steel wire. The electropolymerization process was carried out at a constant deposition potential, applied to the corresponding aqueous electrolyte containing aniline and silica nanoparticles. The applicability of the fiber coating was examined by headspace-solid phase microextraction of some environmentally important polycyclic aromatic hydrocarbons, as model compounds, from aqueous samples. At the optimum conditions, the relative standard deviation values for a double distilled water spiked with the selected compounds at 40 ng L-1 were 6–13% (n = 3) while the limit of detection results were between 1 and 3 ng L-1. In the second chapter, an extracting medium based on chitosan-polypyrrole magnetic nanocomposite was synthesized by chemical polymerization for micro-solid phase extraction for the determination of naproxen in aqueous samples. Influencing parameters on the morphology of chitosan-polypyrrole magnetic nanocomposite and different parameters influencing the extraction efficiency of naproxen were investigated and optimized. The limits of detection (3Sb) of the method were 0.015 mg L−1 (n=3) and the relative standard deviation for water sample spiked with 0.1 mg L−1 of naproxen was 3% (n= 5).In the third chapter, a polypyrrole film containing dodecyl sulfonate and H2PO4- as organic and inorganic counter ions was electrodeposited on a stainless steel wire to be used for insulating purposes. The applicability of this unbreakable fiber coating was examined by headspace solid phase microextraction of some selected chlorobenzenes, as model compounds, from aqueous samples. The results show that at constant concentration (0.05 %) of dodecyl sulfonate, extraction efficiency was enhanced as the H2PO4- content raised to 3 mg. The relative standard deviation values for the selected chlorobenzenes at 30 ngL-1 were 3–8% (n = 3) and the limit of detection for the studied compounds were between 0.5 and 1 ng L-1. Section II: In the first chapter, solid phase microextraction fiber coating based on modified silica-polyamide nanocomposite was electrospun on a stainless steel wire. The applicability of the new fiber coating was examined by headspace solid phase microextraction of some selected chlorobenzenes, as model compounds, from aqueous samples. For synthesis of modified silica-polyamide nanocomposite coating, first, polyamide was dissolved in formic acid and various amounts of different silica nanoparticles were added. Then this solution was withdrawn into a syringe which was eventually located in a syringe pump and a voltage of 16 kV was applied between the needle and the collector for the nanofibers production. At the optimum conditions, the relative standard deviation values for a double distilled water spiked with the selected compounds at 100 ng L-1 were 4–12% (n = 3) and the limit of detection for the studied compounds were between 5 and 30 ng L-1.
    In the second chapter, a magnetic polyurethane nanocomposite was synthesized by electrospinning technique and applied for isolation and preconcentration of fluoxetine form aquatic and biological samples. By embedding magnetic nanoparticles into polyurethane nanofibres, they can be easily removed by application of an external magnetic field with no need to perform any additional centrifugation or filtration of the sample, making the extraction/desorption processes more convenient and faster. The detection limit of the developed method under optimized conditions and the use of a fluorescence spectrometry was 1 µgL−1. The relative standard deviation (n = 5) at a concentration level of 150 µgL−1 was 2 %.
    In the third chapter, a type of nanocomposite material based on polybutylene terephthalate and NiO nanoparticles was prepared by electrospining technique and used as coating for solid phase microextraction. The applicability of the synthesized new coating was examined by headspace solid phase micro extraction and gas chromatography mass spectrometry detection for the determination of volatile organic compound in aqueous samples. The use of NiO nanoparticles in polybutylene terephthalate polymer structure is an efficient way to the enhancement of surface area and porosity of fiber coating and surly improves the extraction efficiency. Under the optimized conditions, the detection limits of the method were < 5 ng L−1 using selected ion monitoring mode.
    In the fourth chapter, an extensive study on the roles of inorganic oxide nanoparticles on the extraction efficiency of four polyethylene terephthalate -based nanocomposites was carried out. The applicability of new fiber coatings were examined by headspace-solid phase microextraction of some environmentally important volatile organic compound, as model compounds, from aqueous samples. Parameters affecting the morphology and capability of the prepared nanocomposites including the type of nanoparticles, effect of the nanoparticle doping levels and the coating time were optimized. Among the synthesized nanocomposites, the one with SiO2 nanoparticles exhibited prominent extraction efficiency. At the optimum conditions, the relative standard deviation values for a double distilled water spiked with the selected compounds at 50 ng L-1 were 2–6% (n = 3) while the limits of detection results were between 0.7 and 0.9 ng L-1
  9. Keywords:
  10. Conductive Polymer ; Solid Phase Microextraction ; Fluoxetine ; Gas Chromatography ; Electrospinning ; Magnetic Solid Phase Extraction ; Gas Chromatography/Mass Spectrometry (GC/MS) ; Water Samples ; Biological Sample ; Polymer Nanocomposits ; Inorganic Nanoparticles ; Naproxen

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