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Study On The Synthesis And Performances Of Novel Separate Medium

Posted on:2006-10-18Degree:MasterType:Thesis
Country:ChinaCandidate:M CaiFull Text:PDF
GTID:2121360182967943Subject:Analytical Chemistry
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Solid-phase microextraction (SPME) is a new sample pretreatment technique, which can integrate sampling, extraction, preconcentration and sample introduction into one step. It has advantages of simplicity, fast, solvent free, portable. This method has been successfully applied to the environmental, food, pharmaceutical, clinical, biological and forensic science areas.The key to SPME technique lies in the coating materials of the fiber. However, only few coatings for polar compounds are commercially available, which are low thermal, chemical stability. All these limit its application.. It is very important for SPME to develop novel coatings with polarity, thermal ability, higher sensitivity and longer life.Sol-gel chemistry provided with an applicable and convenient way to improve the thermo- and solvent stability of coating. This kind of coating was porous and could reach extraction equilibrium within less time relative to the commercials.PEG is commonly used as stationary phase in gas chromatography to separate polar analytes, easy to be modified and the elements of stationary phase are similar to that of fiber coating in SPME. In this paper, PEG silicate was synthesized from MeSiCl3 and PEG and used to prepare the SPME fiber coating and stationary phase by sol-gel technology. Then, their performances in gas chromatography were investigated. In addition, the extraction performance also had been investigated in order to get further knowledge of the novel coating.On the other hand, a novel superamolcule cucurbituril was used to prepare another SPME fiber through sol-gel method.The main contents in this thesis are described as follows. 1.ReviewIn this thesis, some aspects on SPME technique were reviewed, including its history, device, fundmental theory, effects on extraction performance, application etc. Here, the development of coating material was summed up in detail. 2.Preparation of PEG silicate SPME fiberThree kinds of PEG silicates were synthesized from MeSiCl3 and PEG with different molecule weight. Then, the PEG silicates were used to prepare three kinds of fiber coatings by sol-gel technology. 3.Evaluation and application of the homemade SPME coatingComparing the extraction amount of three fibers on chlorophenols at each optimal condition, PEG 2000 silicate fiber was selected for further study.The coating has a high thermal stability (340°C), long lifetime and solvent stability (organic solvent). Without derivitation, chlorophenols (especially pentachloropphenol), aromatic amines and PAEs were analyzed using this fiber by HS-SPME-GC-FID method. Good linearity and limits of detection were obtained. For three types of compounds, the linear ranges were 0.1-103, 10"3103, 0.005-50 /ig/L, respectively. The limits of detection varied from 0.11 to 0.183 ng/L, 6.33 to 76.3 pg.L"1, 0.00136 to 0.238 ng/L. All the results are better than those reported in the literature. These pollutants in soil samples were all obtained good recoveries. Compared with commercially available SPME fibers polyacrylate (PA) and poly (dimethylsiloxane) (PDMS), the PEG silicate coating exhibited greater extraction capacity. 4.1nvestigation of the extraction mechanism of the PEG silicate fiber coatingThe homemade coating possesses simikir character to mixed coating PDMS/DVB, but its extraction to analyte was less influenced by interfering and it had both broader linear range and higher recoveries compared with PDMS/DVB. Meanwhile, the extraction capacity of the PEG silicate coating were significantly greater than that of PA and when concentration was not high, and interfering compound had less effect on the extraction amount of analyte for homemade coating than for PA. In a word, novel coating had higher extraction capacity than PA and a broader linear range than PDMS/DVB under the same condition.5.Studies on the preparation and performance of the gel stationary phase containing modified PEG in gas chromatographyAs a stationary phase, PEG 2000 silicate was applied to prepare a gel column through sol-gel technology. Its performance in gas chromatography has been investigated. The results showed its high thermal stability, polarity and goodselectivity for aromatic positional isomers, polycyclic aromatic hydrocarbons ect.. The selectivity was dominated by hydron-bond and dipole-dipole interaction. 6. A novel coating for determination of the phthalate esters migrated from plastic samples by Headspace Solid-phase MicroextractionA novel fiber containing cucurbituril was firstly prepared through sol-gel technology and evaluated. In order to investigate the potential hazards to children, determination of the migration of PAEs from plastic toy products into simulant sweat, was carried out. The method showed good linearity (three or four orders of magnitude), low limits of detection (at ng.l"1 level). The relative standard derivations (RSD) were below 5.5% (n=5). The concentrations of PAEs in simulant sweat were at the level of //g.l"1 and RSD were in the range between 4.6% and 9.7% (n=3).
Keywords/Search Tags:Solid-phase Microextraction, Stationary phase, Sol-gel method, Polyethylene glycol silicate, Cucurbituril
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