National Repository of Grey Literature 83 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Study of properties of UV-photochemical generation of volatile compounds od antimony
Adámková, Dominika ; Červený, Václav (advisor) ; Hraníček, Jakub (referee)
The master thesis deals with comparison of atomic fluorescence spektrometry and high resolution continuum source atomic absorption spektrometry for three methods generation of volatile compounds Antimony. In both methods of atomic antimony detection, it compares the most common chemical generation of volatile compounds (hydrides) with two alternative methods - electrochemical and UV - photochemical. The values of performance parameters for the determination of Sb(III) and Sb(V) were determined for all the above combinations. In the case of chemical generation, a surprisingly almost four times higher limit of detection of Sb(III) was found in connection with AFS detection than AAS detection. The final part was devoted to UV - photochemical vapor generation, with AAS detection for Sb(III) reaching limit of detection 4,96 ppb, for Sb(V) 8,63 ppb. Although UV - photochemical generation of volatile antimony compounds did not reach such performance parameters as chemical or electrochemical generation, it was observed that the sensitivity of antimony determination increased greatly when introducing oxygen into the apparatus. The interference study also found a significant positive effect of Fe(II) on the generation efficiency, and this modification partially persisted without further introduction of these...
Analysis of fruits and vegetables extracts by atomic spectrometry methods
Petráňová, Karolína ; Hraníček, Jakub (advisor) ; Kozlík, Petr (referee)
EN The aim of this thesis was to determine selected elements - chromium, manganese, copper, iron and zinc - in fruit and vegetable extracts. The method used for measurement was atomic absorption spectrometry with flame atomization. First, the optimal conditions for the measurement were found. Then the basic characteristics of the determination of each element under optimal conditions were determined. The determined optimal conditions were used in the analysis of real samples of extracts. The samples were appropriately diluted before measurement. The content of all 4 selected elements was determined in all 36 extracts from fruits and vegetables. All results were provided with statistical evaluation.
Optimization of experimental setup for chemiluminescent determination of cobalt ions
Pastrňáková, Aneta ; Hraníček, Jakub (advisor) ; Dian, Juraj (referee)
The presented thesis deals with finding the optimal experimental setup for the chemiluminescent determination of cobalt ions by the technique of flow injection analysis (FIA) and sequential injection analysis (SIA) and comparing the achieved results of the determination. The determination is based on a chemiluminescent reaction, essence of which is oxidation of luminol with hydrogen peroxide in an alkaline solution in a flow system in the presence of cobalt ions, which acts as a catalyst of the reaction. In the experimental part of the work, a suitable setup for the detection of chemiluminescent light emission was found, followed by a suitable setup of the FIA and SIA systems for the determination of cobalt ions. For the detection of radiation, a glass spiral tube was selected, which was the most suitable for chemiluminescent measurement, compared to other experiments performed with different. In the next part of the work, optimal conditions for cobalt ions determination were experimentally found. As for the FIA technique, the volume flow rate of hydrogen peroxide, luminol and cobalt ions solutions was optimized. Furthermore, the concentration of the hydrogen peroxide solution and luminol. Last but not least, the dosing volume of the cobalt ions solution and the pH of the luminol solution were...
Electrochemical generation of tellurium volatile compounds with atomic absorption spectrometry
Labancová, Katarína ; Hraníček, Jakub (advisor) ; Jelínek, Ivan (referee)
EN The present diploma thesis deals with the electrochemical generation of volatile tellurium compounds in connection with atomic absorption spectrometry with the main goal to increase the response of the tellurium signals and thus expand the existing knowledge about this element. Tellurium is one of the heavier elements that forms less stable volatile compounds. The reason for choosing these elements was the fact that its concentration increases mainly in landfills where it is released into the environment, which can have an ecological impact and an impact on human health. In the first step, two types of electrochemical cells were constructed - a thin-film flow electrochemical cell with and without an ion exchange membrane and an apparatus with a flow injection arrangement. The choice of cell types, cathode and anode material and apparatus design was chosen based on a literature research. Attention was paid to the optimization of reaction conditions for electrochemical generation of volatile tellurium compounds, which significantly affect the efficiency of generation using a heated quartz tube atomizer. The optimized parameters were electrolyte concentration, carrier gas volume flow rate, electrolyte volume flow rate and generation current. In the second step, the effect of the temperature of the...
Determination of Copper in Food Supplements by AAS
Hadbavníková, Alexandra ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
EN This bachelor thesis deals with the determination of copper in the form of copper ions in selected food supplements by atomic absorption spectrometry. The first step of the experiment was to find the optimal measurement conditions for the parameters: beam height above the burner edge, burner horizontal position, fuel flow rate, burner angle and spectral interval width. Subsequently, the calibration dependence was determined and the basic measurement characteristics were calculated: repeatability, sensitivity, limit of detection (0.019 mg dm−3 ) and limit of quantification (0.065 mg dm−3 ) at the burner position 0 ř. Interference studies were performed for the presence of iron, manganese and sodium elements in selected food supplements because of theirs increased concentrations. These selected food supplements were analysed: Spektrum 50, Supradyn Energy Complex, Center from A to iron, GS Extra Strong Multivitamin, Caltrate Plus, DAS Gesunde Plus, A-Z Multispektrum and Calibrum 50 Plus. Selected samples were converted to solutions using three procedures: decomposition in water at room temperature, decomposition in nitric acid at room temperature and decomposition in nitric acid at high temperature. The determination of copper itself was performed using a GBC 933 AA spectrometer and the results...
Determination of iron and potassium in honey samples
Česká, Miroslava ; Hraníček, Jakub (advisor) ; Teplý, Pavel (referee)
This bachelor thesis was focused on the determination of potassium and iron content in the selected samples of honey. These elements have been determined by the atomic absorption spectrometry with flame atomization. The samples used in the analysis were representing the species of flower, honeydew, and mixed honeys. In most of the cases, the samples came from small private beekeepers. For comparison, there were also some samples of purchased honey included. At first, with using the standard solutions, there were optimized the height of the beam above the burner and the acetylene flow rate used as a fuel. The optimal conditions for the determination of iron content were: the height was 6 mm and the flow rate was 3.0 L min-1 . For the determination of the potassium content, the optimal conditions were: the height was 7 mm and the flow rate was 2.5 L min-1 . To check the accuracy of the measurements, a series of iron solutions with a concentration of 10.0 mg L-1 were prepared and the obtained signals were compared. Under the optimal conditions for each element there was calculate the limits of detection and quantification and repeatability of measurements. Last but not least, the measurement of selected elements followed. Honey sample solutions were prepared by dissolving of 6.0 g of honey in 50 mL of...
Determination of selected elements in potato tubers by atomic absorption spectrometry
Fořtová, Lucie ; Hraníček, Jakub (advisor) ; Kozlík, Petr (referee)
The main aim of this bachelor thesis was a determination of the elements K, Mg, Ca, Na, Zn and Fe in the potato tubers and in their boiled solution using the method of flame atomic absorption spectrometry. The chosen samples were late consumer potato tubers of Granada cultivar (boiling type B). It was necessary to optimize working conditions before the sample analysis. The optimal flow rate of acetylene ranged from 2.0 to 2.5 l/min using the flame acetylene-air. The flame acetylene-nitrous oxide was used only for calcium with flow rate 6.0 l/min. The optimal height of a beam above the burner edge was measured in interval 5 to 7 pieces of defined scale mentioned in a manual for spectrometer GBC 933 AA. Using the optimal conditions, the basic characteristics for individual methods of determination were characterized (LOD, LOQ, LDR, sensitivity, repeatability). Limits of quantification were following: 78, 31, 7.0, 8.0, 190 and 71 μg/l for K, Na, Mg, Ca, Fe and Zn, respectively. The optimal conditions were used for the determination of the selected elements in samples. The solutions were prepared from diversely processed potato tubers (whole, whole without skin, chopped without skin, skin) by boiling into deionized water. After the samples had cooled down, the concentrated nitric acid was added...
Determination of lead and cadmium in fruits and vegetables extracts by atomic absorption spectrometry
Záškodová, Terezie ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The content of this thesis was to analyse fruit and vegetable extracts. In the samples, the concentration of lead and cadmium was determine by atomic absorption spectrometry. First, it was necessary to conduct an optimalization study to find the optimal conditions of the method and select the appropriate method of atomization of the sample. It was chosen between flame and electrothermal atomization. For optimization, the following parameters were studied for atomization in flame: beam height above the burner, fuel flow rate, horizontal burner position, spectral interval width and lamp supply current. An optimization study for electrothermal atomization included the effect of atomization a pyrolysis temperature on signal size. Standard lead and cadmium solutions were used to determine the detection limits of the instruments used. The limit of detection in flame atomization was for lead respectively cadmium 0,002 mg/l, resp. 0,003 mg/l. In electrothermal atomization the detection limit was for lead, resp. cadmium 0,026 μg/l, resp. 0,029 μg/l. The experimentally determined values were statistically processed and the lead and cadmium contents were compared with the lead and cadmium limit values that may be contained in a sample of fruit and vegetables according to Commission Regulation (EC) No...

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