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Optimization of microextraction technique for analysis of water by chromatographic methods
Otrubová, Lucie ; Čabala, Radomír (advisor) ; Sobotníková, Jana (referee)
New liquid phase microextraction (LPME) has been optimized. Plastic adapter with tapered tip was used as extraction device. Concentration of analytes was determined by GC-MS. Face centered design was used to optimize LPME and the results were evaluated by Minitab 16 programme. Volume of sample, volume of extraction solvent, stirring rate, extraction time, ionic strength and time after microextraction were optimized. Response of system was defined as the sum of the peak relative areas. Toluene, tetrachlorethylene, ethylbenzene, xylenes, mesitylene and naphthalene were the studied analytes. Methylhexadecanoate was used as an internal standard. Optimal system conditions were as follows: 20 mL sample volume, 300 μL extraction solvent volume, 20 minutes, stirring speed 700 rpm, no addition of salt, and time after microextraction 3.5 minutes. Determination coefficient was 0.9700 and the lack-of-fit was insignificant which indicated good agreement of the model with the experimental data. The preconcentration factor ranged from 26 (tetrachlorethylene) to 39 (xylenes). The microextraction yield was varied from 39.5% (tetrachlorethylene) to 59.1% (p-xylene and m-xylene). The new method was tested by analyzing real samples of tap water, river water and water from the sewage treatment plant. The samples were...
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Optimization of microextraction technique for analysis of water by chromatographic methods
Otrubová, Lucie ; Čabala, Radomír (advisor) ; Sobotníková, Jana (referee)
New liquid phase microextraction (LPME) has been optimized. Plastic adapter with tapered tip was used as extraction device. Concentration of analytes was determined by GC-MS. Face centered design was used to optimize LPME and the results were evaluated by Minitab 16 programme. Volume of sample, volume of extraction solvent, stirring rate, extraction time, ionic strength and time after microextraction were optimized. Response of system was defined as the sum of the peak relative areas. Toluene, tetrachlorethylene, ethylbenzene, xylenes, mesitylene and naphthalene were the studied analytes. Methylhexadecanoate was used as an internal standard. Optimal system conditions were as follows: 20 mL sample volume, 300 μL extraction solvent volume, 20 minutes, stirring speed 700 rpm, no addition of salt, and time after microextraction 3.5 minutes. Determination coefficient was 0.9700 and the lack-of-fit was insignificant which indicated good agreement of the model with the experimental data. The preconcentration factor ranged from 26 (tetrachlorethylene) to 39 (xylenes). The microextraction yield was varied from 39.5% (tetrachlorethylene) to 59.1% (p-xylene and m-xylene). The new method was tested by analyzing real samples of tap water, river water and water from the sewage treatment plant. The samples were...
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Toxicity determination of polyfluorinated and perfluorinated organic substances
Otrubová, Lucie ; Čabala, Radomír (advisor) ; Rucki, Marian (referee)
The goal of the bachelor thesis was the determination of toxicity of fluorotelomer alcohols. The toxicity was measured as ET50 by the oligochaete Tubifex tubifex. This test belongs to group of alternative methods which are faster and cheaper but they provide reliable data as well as the presently used classical methods. ET50 is the exposure time when 50 % of Tubifex tubifex individuals stop moving. EC50 of magnese chloride dihydrate was measured for the control of its correctness of determination and its acute toxicity indice is equal to log (EC50) = -0,845 ± 0,033 [log (mmol/l)]. EC50 is the concentration of the tested substance when 50 % of Tubifex tubifex individuals stop moving. 1H,1H,2H,2H-perfluorooctan-1-ol and 1H,1H,2H,2H-perfluorodecan-1-ol were the tested substances. Destilled water and solution of dimethyl sulfoxide in water (5 %) were used to prepare the saturated solutions of the tested substances. The conncentrations of the saturated solutions were determined on GC-MS by absolute calibration method. The value of log (EC50) for dimethyl sulfoxide solution was measured to determine how it influences Tubifex tubifex during exposure time of 2,5 hours. KEY WORDS: fluorotelomer alcohols, alternative method, Tubifex tubifex
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