National Repository of Grey Literature 56 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
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 in order to determine trace Cd concentrations by atomic absorption spectrometry (AAS). Several reaction modifiers based on inorganic salts and complexes of CrIII+, CoII+, TiIII+, TiIV+ were tested to improve analytical performance and generation efficiency.
Trapping of volatile cadmium species on gold surfaces for atomic absorption spectrometry
Sagapova, Linda ; Svoboda, Milan ; Matoušek, Tomáš ; Kratzer, Jan
Simple preconcentration step was developed for cadmium determination after chemical vapor generation prior to atomic absorption spectrometric detection. Chemical vapor generation of cadmium was performed in the presence of Cr3+/KCN as modifiers.
Atomization of hydride forming elements in dielectric barrier plasma discharges
Baranová, Barbora ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
The aim of this diploma thesis was to optimize the atomization conditions of two hydride forming elements - bismuth and tellurium in dielectric barrier discharge (DBD) plasma atomizers using atomic absorption spectrometry (AAS) as a detector. Two types of electrode constructions of planar DBD atomizers were studied: glued and sputtered electrodes while two construction of high voltage power supply sources were investigated employing either a sinusoidal or square wave modulation of high voltage function. The effect of the gas phase dryer included in the apparatus upstream the atomizer was also investigated. A nafion membrane tube dryer was identified as the most effective one. Its efficiency was verified using optical emission spectrometry. With the nafion tube included in the apparatus, two main parameters of DBD atomizers were optimized: the voltage of the power supply source and argon flow rate, which served as a discharge gas. Using optimal conditions, analytical characteristics were determined for all atomizers used and these were subsequently compared with those achieved in an externally heated quartz (multi)atomizer (MM)QTA. In the case of bismuth, the optimal argon flow rate was determined to be 75 cm3 min-1 for all atomizers. The optimal value for the power supply source with sinusoidal...
Determination of As2O3 in homeopathic products Arsenicum Album using atomic absorption spectrometry with hydride generation
Cmuntová, Kateřina ; Červený, Václav (advisor) ; Kratzer, Jan (referee)
This bachelor thesis is intent on As determination in various types of homeopathic remedy Arsenicum Album which are available in Czech Republic. The method selected for this determination is atomic absorption spectrometry with hydride generation. The content of As2O3 in recommended daily dose of homeopathic was confronted with toxicologically referred maximal dose and it was discussed if there is any risk of health damage by using Arsenicum Album.
Modular design for in-atomizer preconcentration of hydride forming elements with AAS detection
Novák, Petr ; Kratzer, Jan (advisor) ; Korunová, Vlasta (referee)
Modular design of hydride trap-and-atomizer device for AAS is constructed and tested. Modular design enables to test different preconcentration surfaces easily. Efficient in- atomizer preconcentration allows to reach detection limits of hydride forming elements at ultratrace levels. Bismuth and arsenic were chosen as model analytes and their preconcentration efficiencies were quantified employing quartz and sapphire as preconcentration surfaces. The results reached in the modular design were compared to those found previously in the compact quartz trap-and-atomizer device. The performance of the modular design is fully comparable with that of compact trap-and-atomizer design. Modular design can thus be employed for testing of novel preconcentration surfaces.
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
UV-Photochemical Generation of Volatile Compounds for Determination of Se in Selected Nutrition Supplemets
Kolorosová, Alžběta ; Červený, Václav (advisor) ; Kratzer, Jan (referee)
The option of UV-photochemical generation of volatile compounds coupled with atomic absorption spectrometry for the determination of selenium in the real samples (pills) is described in this work. The optimum conditions of UV-photochemical generation of volatile compounds was investigated. After that the limit of detection as low as 58 ppt for Se+IV and 30 ppt for Se+VI was obtained. The nutrition supplement, which contain selenium, was choosen and analyzed by this method. Iodide and cupric interfere the determination of selenium in the real samples.
A novel AAS atomizer based on a dielectric barrier plasma discharge
Novák, Petr ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
Atomization of arsine in a novel hydride atomizer for atomic absorption spectrometry (HG-AAS) was thoroughly optimized. This plasma atomizer is based on a dielectric barrier discharge (DBD). Sensitivity and detection limit reached 0.48 s ng-1 As and 0.16 ng ml-1 As, respectively, under optimum atomization conditions (Ar discharge using a flow rate of 60 ml min-1 Ar, DBD power 17 W). Analytical figures of merit reached in DBD are comparable to those found in an externally heated quartz tube multiatomizer (MMQTA) that was chosen as a model of conventional approach to hydride atomization in HG-AAS. An extent of interferences (Se, Sb, Bi) during As determination was investigated comparing both MMQTA and DBD atomizers. The later one was found to be more resistant towards interferences. A simple preconcentration of As in a DBD atomizer was reached after oxygen introduction into the Ar plasma in the DBD resulting in analyte retention in the atomizer followed by its volatilization once the oxygen flow is switched off. Preconcentration efficiency of 100 % was reached and detection limit improvement by a factor of ten was achieved (0.01 ng ml-1 As, preconcentration period 300 s).
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)

National Repository of Grey Literature : 56 records found   1 - 10nextend  jump to record:
See also: similar author names
2 Kratzer, J.
6 Krätzer, Jan
Interested in being notified about new results for this query?
Subscribe to the RSS feed.