Preparation Of Several Nanomaterials And Its Application In Solid-phase Microextraction

Since the introduction of solid-phase microextraction?SPME?in the 1990s,differe nt types of coating have shown their crucial role in extraction efficiency.SPME is based on the partitioning of target analyte?s?between the sample matrix and a stationary phase,which is typically immobilized on a fiber or wire.The coating type of SPME plays a crucial role in the efficiency of the extraction,as it is the main factor affecting the distribution constant between the sample matrix and the immobilized phase.The chemical and physical properties of the sorbent material have a great impact on the overall extraction performance,including method sensitivity,selectivity and reproducibility.In recent years,nanomaterials have been attractive for extraction techniques because of their high porosity,which improves the extraction efficiency.The remarkable thermal,mechanical and chemical stability of nanomaterials ha ve resulted in their usage as SPME coatings.In present,many inorganic nano-metal compounds have been developed as SPME coatings,such as Al₂O₃,TiO₂,Fe₂O₃,ZnO,Li₂O and ZrO₂,Co₃O₄ nano-coatings and so on.The current work introduced the new development and preparation methods of nanomaterials briefly,but put an emphasis on the development of carbon nanomaterials,MOF materials and inorganic non-metallic nanomaterials in SPME coating applications.The main study work included as follows:1.A new bonding method was developed in which molybdenum oxide was coated on a steel wire substrate to use as a solid-phase microextraction fiber coating and combined with gas chromatography to analyze environmental pollutants.It was found that the prepared molybdenum oxide material exhibited nanobelt structure with uniform size and good dispersion.In addition,there are a large number of small protrusions on the surface of the nanobelt.These features provide a large specific surface area for extraction.Molybdenum oxide exhibits high extraction selectivity for polycyclic aromatic hydrocarbons due to its modest coordination effect.After optimizing the extraction influence factor,the extraction method with detection limit as low as 1.25?g L^-1 was achieved,and the calibration curve was linearly correlated in the range of 2.0-600?g L^-1.In addition,the method was verified for repeatition with an RSD value below 6.4%.The molybdenum oxide coating has high scratch resistance and is effective in preventing coating wear and failure.Due to its high thermal and chemical stability,the service life of the coating is improved and can be used up to 150 times without significantly reducing the extraction performance.Finally,the prepared fibers have comparable extraction capacity and higher distribution coefficient as commercial polyacrylate fibers.2.We have developed a solid phase micro-extraction fiber absorbent:zinc acetate,thiourea,and silver nitrate for the determination of polycyclic aromatic hydrocarbons in environmental water samples.The results illustrated that the adsorbent is rich in spherical protrusions,provides a large specific surface area,and is uniformly dispersed.The new solid phase microextraction fiber converts the extraction and preconcentration of the target analyte into a single step.The development and evaluation of the method was carried out with four polycyclic aromatic hydrocarbons as the target analytes.Some key parameters affecting the extraction efficiency were optimized,including extraction time,extraction temperature,desorption time,desorption temperature and salting out effect.Under the optimal conditions,the obtained analytical coefficients showed a good linear correlation function with values ranging from 0.9965 to 0.9993 and limit of detection range from 0.05 to 0.2?g L^-1.The method showed satisfying reproducibility with a relative standard deviation ranging from4.2%to 6.4%.Finally,the new development method was applied to the determination of polycyclic aromatic hydrocarbon compounds in water samples of Yellow River,and good separation and analysis results were obtained.3.A novel method for preparing a titanium dioxide nanotube array,a secondary anodization method was developed.Porous TiO₂ nanotube array was used as template to prepare TiO₂ nanotube array by secondary anodic oxidation.After repeated ly experiments,the conditions were optimized:reaction time,HF concentration,reaction temperature and voltage to control the growth of TiO₂ nanotubes.A TiO₂ nanotube array system with uniform diameter and adjustable pore size was prepared.TiO₂ nanotubes with good thermal and chemical stability were obtained by effective stripping method,which solved the defects of traditional TiO₂ nanotubes agglomerating agglomeration or nozzle irregularity.