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HG-AAS with atomization in a dielectric barrier plasma discharge: method optimization and analytical applications
Zurynková, Pavla ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
The aim of this diploma thesis was to optimize in detail atomization conditions for antimony hydride in a novel plasma atomizer based on a dielectric barrier discharge (DBD) with atomic absorption spetrometric detection. Argon was found as the best DBD discharge gas employing a flow rate of 50 ml min-1 Ar while the DBD power was optimized at 30 W. Analytical figures of merit including interference study of As, Se and Bi have been subsequently investigated and the results compared to those found in an externally heated quartz tube atomizer (QTA). The limit of detection reached in DBD (0.15 ng ml-1 Sb) is comparable to that observed in QTA (0.14 ng ml-1 Sb). Finally, possibility of stibane preconcentration in a DBD atomizer was studied. Preconcentration efficiency of 102 ± 6 % was found under optimized conditions.
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Spectrometric determination of selected metals in the samples from old ecological burden area
Zurynková, Pavla ; Kratzer, Jan (advisor) ; Spěváčková, Věra (referee)
This bachelor thesis is focused on heavy metals pollution in the Králíky town and its vicinity, located in the Pardubice region. This region was selected because there had been a Tesla factory producing fluorescent lamps. Moreover, there is also a waste disposal of the fluorescent lamps wasters and other dangerous waste located about two kilometers far from the former factory. Soil samples from the waste disposal area as well as river sediment, samples taken in the Tichá Orlice river and the Králický brook have been analyzed Mercury, cadmium, lead, chromium, nickel, copper and arsenic levels in the samples were measured by inductively coupled plasma - mass spectrometry. The total mercury content has also been measured with single-purpose atomic absorption spectrometer AMA-254. An optimization of leaching conditions of the elements was performed prior the analysis of the samples employing certified reference material. High levels of mercury, cadmium, lead, chromium, nickel and copper have been found in the waste disposal area. Regarding the sediment samples the highest levels of pollution have been detected near outfall of the sewage water from the industrial area in the Králíky town (former Tesla factory and recent metal plating industry). The concentration of heavy metals in other sediment...
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Next generation of hydride atomizers based on dielectric barrier plasma discharge
Kráľová, Zuzana ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for selenium and lead hydrides in a dielectric barrier discharge (DBD) plasma atomizer with detection by atomic absorption spectrometry (AAS) were investigated in this work. Two designs of DBD atomizers were studied, the first one with glued electrodes and the second one with sputtered electrodes. The main experimental parameters were optimized, including supplied power and discharge gas (argon) flow rate. Additionally, the effect of several dryers was studied. Analytical figures of merit were determined for both plasma atomizers under the optimized conditions and compared to multiatomizer (MMQTA) as the most common hydride atomizer. The optimum flow rate for selenium determination was 75 cm3 min-1 Ar for both DBD atomizer designs as well as for MMQTA. In case of lead hydride atomization, ideal flow rate of argon was 175 cm3 min-1 for DBD atomizer with glued electrodes and 150 cm3 min-1 with DBD atomizer with sputtered electrodes, while MMQTA required only 100 cm3 min-1 Ar. The optimal power supply for DBD with sputtered electrodes was found significantly lower at 7.3 W for selenium and 13.3 W for lead. A dryer based on nafion membrane was found as the most effective for both analytes studied. Its efficacy was verified by optical emission spectrometry. As for analytical...
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Chemical vapor generation of cadmium for analytical atomic spectrometry
Sagapova, Linda ; Kodríková, Barbora ; Svoboda, Milan ; Musil, Stanislav ; Kratzer, Jan
Chemical vapor generation of cadmium volatile compounds was optimized, several reaction modifiers based on inorganic salts and complexes of CrIII+, CoII+, TiIII+, TiIV+ were tested. Their use resulted in 4-5 times enhancement in sensitivity, reflected also in corresponding increase of generation efficiency and better repeatability. Generation efficiency was determined from a comparison between sensitivities obtained with chemical vapor generation and conventional solution nebulization, both simultaneously coupled with inductively coupled plasma mass spectrometry. The identity of the generated cadmium compounds was identified.
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Information System Assessment and Proposal of ICT Modification
Krätzer, Jan ; Novák, Lukáš (referee) ; Koch, Miloš (advisor)
This diploma thesis is focused on the appraisal of the current state and the proposal for changes of the selected company Masaryk University that serves as a supporting element for the employees who deal with the actions of legally compulsory service. The appraisal of the current state of the information system is based on the analysis; the change proposals were sumbitted to the employees who are responsible for the operation and development of the information system.
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Optimization of chemical generation and subsequent atomization of volatile cadmium species for atomic absorption spectrometry
Sagapova, Linda ; Kratzer, Jan (advisor) ; Marschner, Karel (referee)
Generation and atomization of cadmium volatile compounds was optimized in this work in order to determine trace Cd concentration levels by volatile compound generation (VCG) with subsequent detection by atomic absorption spectrometry (AAS). Three designs of volatile compound generators have been tested including a conventional hydride generator in flow injection analysis (FIA) mode, a batch generator as well as a generator of volatile compounds of transition metals. The generation efficiency of Cd species was quantified as low as 4 % in the conventional hydride generator. Providing that dissolved oxygen was removed from the reaction solutions, the generation efficiency of Cd increased to 12 % in the same experimental arrangement. The highest Cd generation efficiency of 54 % was reached in the generator of volatile compounds of transition metals. In this set up a detection limit of 0.07 ng ml-1 Cd and a sensitivity of 3.2 s ng-1 Cd, respectively, were reached. Moreover, the structure of the volatile Cd species generated was identified as free atoms in all experimental arrangements of the generators investigated. Keywords atomic absorption spectrometry, cadmium, generation of volatile compounds, atomization of volatile compounds
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Mechanism of atomization of selected hydride forming elements in an externally heated quartz tube atomizer and a dielectric barrier discharge atomizer
Juhászová, Lucie ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for tin hydride in the planar dielectric barrier discharge (DBD) plasma atomizer were optimized with detection by atomic absorption spectrometry (AAS). The effects of apparatus arrangement such as the shape of a waveform function of the high voltage power supply source, DBD atomizer design as well as presence of a dryer tube filled with NaOH pellets to prevent residual aerosol and moisture transport into the DBD were investigated in detail. The optimal experimental setup consisted of a square wave high voltage power supply source coupled to a DBD with vapor-deposited electrodes in the presence of NaOH dryer upstream the DBD atomizer. Argon was found as the best discharge gas under a flow rate of 120 mL min-1 while the DBD optimum high voltage supply rate was 7 kV. A sensitivity of 0.05 s ng-1 Sn and a limit of detection of 1.1 ng mL-1 Sn were reached under optimized conditions. Optimization of the whole experimental setup resulted in 7-fold improvement of sensitivity compared to the original arrangement consisting of a sinusoidal source coupled to a DBD atomizer with glued electrodes in absence of the dryer. Keywords atomic absorption spectrometry, hydride generation, hydride atomization, quart tube atomizer, dielectric barrier discharge (DBD)
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Speciation analysis of mercury in liquid and gaseous samples
Žídek, Radek ; Kratzer, Jan (advisor) ; Spěváčková, Věra (referee)
Generation efficiency of four mercury species, namely elemental mercury and hydrides of methyl-, ethyl- and phenylmercury from liquid samples was quantified. The species chemically generated were quantitatively trapped on a gold-coated amalgamator to be subsequently determined by AMA-254 technique. Three types of construction of volatile species generators were compared. Generation effciciency among the species was comparable, fluctuating around 60% in the conventional flow injection generator equipped with a gas liquid separator with forced outlet. Better results were reached for elemental mercury and methylmercury hydride in an automated batch generator system. Generation efficiency was higher than 90% for these two species and between 60 to 80% for ethyl- and phenylmercury hydrides, respectively. Speciation analysis of elemental mercury and sublimate in gaseous samples was optimized. These two species dominate in flue gases produced during coal combustion or waste incineration. Combination of two sorbent tubes packed with alumina and gold-coated alumina enables selective and quantitative retention of both species. Sublimate is trapped on a column packed with alumina while elemental mercury is retained on gold-coated alumina. The capacity of both sorbents was investigated as well as the effect of...
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Miniature plasma DBD atomizer for AAS and AFS
Straka, Marek ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Five designs of dielectric barrier discharge (DBD) atomizers have been constructed and optimized employing arsane as a model analyte. The individual DBD designs differed from each other in the style of electrode attachment, electrode shape and area. An externally heated quartz tube atomizer and another DBD atomizer design that have been studied before were used as reference. All the atomizer designs studied including the reference atomizers were found compatible with detection by atomic absorption spectrometry (AAS) giving comparable sensitivity of 0.44 s ng-1 As and detection limit around 0.2 ng ml-1 As under optimum atomization conditions. However, significant differences in optimum operation conditions were found among the DBD designs in terms of the applied voltage depending strongly on the style of electrode attachment. The design with metal strip electrodes glued to a quartz body requires more than 14 kV to be operated. The design with sputtered electrodes of the same shape can reach the same sensitivity with 8.5 kV. Selected DBD designs have been proven to be compatible also with other spectrometric detectors such as atomic fluorescence spectrometry (AFS) reaching detection limit 0.05 ng ml-1 As or atomic emission spectrometry (AES) with detection limit of 30 ng ml-1 As showing the...
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