|
| |
|
|
Influence of interfering elements on the electrochemical antimony hydride generation
Vacek, Tomáš ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
This thesis is focused on the study of different interfering elements during antimony electrochemical hydride generation. Interferences were studied for electrochemical hydride generation with electrolytic cell and also for chemical hydride generation using sodium tetrahydroborate as a reduction agent. The study included the comparison with oxygen influences. Hydride-forming elements (selenium and arsenic), transition metals (zinc, copper and nickel), different anions (chlorides, sulfates and nitrates) and sodium were tested as interferents. The most serious interferents were hydride-forming elements and nickel, where 100 % signal supression was observed in high interferent concentrations. As opposed to sodium and nickel, where almost none signal supression was observed at all concentrations. Keywords Interferences, electrochemical hydride generation, atomic absorption spectrometry, antimony, electrolytic cell, atomization, hydrides
|
|
|
Antimony determination by electrochemical hydride generation
Suchá, Lenka ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
The aim of the presented bachelor thesis is to study the possibilities of the electrochemical hydride generation of volatile antimony hydride, using two newly constructed electrolytic cells. In this work, the properties of the cells were studied and consequently the basic characteristics of antimony determination obtained using new cells were compared with the chemical hydride generation method. At the beginning of the work, the relevant working parameters of both electrolytic cells were optimized. Under the optimal working conditions the calibration and other characteristics were carried out for antimony determination. Using the electrochemical hydride generation with thin-layer electrolytic cell and tubular cell and chemical hydride generation the sensitivity 3.40·10-3 l·μg-1 , 6.10·10-3 l·μg-1 and 2.10·10-3 l·μg-1 respectively were obtained. Finally, the influence of oxygen introduction in the different part of experimental setup was studied. This oxygen addition caused the characteristic and well-reproducible absorption peak. Key words Atomic absorption spectrometry, electrochemical generation of volatile compounds, quartz tube atomizer, thin-layer and tubular electrolytic cell, antimony
|
|
|
Reducing of Transport Loses by the Determination of Cadmium Using Electrochemical Generation of Volatile Compounds
Kováčová, Darina ; Červený, Václav (advisor) ; Rychlovský, Petr (referee)
The aim of this work was to reduce transport loses during the determination of Cd by using electrochemical generation of volatile compounds connected to AAS. Firstly, optimum experimental conditions were found for analytical determination of Cd using electrochemical generation of its volatile form. The second part of this work was focused on avoiding of cadmium condensation on cold inner walls of inlet tube of the quartz atomizer. The two successful devices connecting directly the separator of gas from the liquid phase and the quartz atomizer were constructed. Thus, the transporting way for volatile form of Cd was made as short as possible. Better results were achieved using the device which contains sintered glass in the bottom part of the gas-liquid separator for further inlet of carrier gas (Ar). Further reducing of transport loses of the volatile form of Cd was achieved using a heating of the inlet tube of the atomizer on 310řC. Thanks to these two improvements of the apparatus ca three times higher sensitivity was reached using the technique of electrochemical generation of volatile form of Cd and AAS detection. Also corresponding depression of the limit of detection (0,064 µg·cm-3 ) was got. Keywords: Determination of Cd, atomic absorption spectrometry, elektrochemical generation of volatile...
|
|
|
Construction of miniature flow-through cells for electrochemical generation of volatile compounds
Hraníček, Jakub ; Rychlovský, Petr (advisor) ; Spěváčková, Věra (referee) ; Komárek, Josef (referee)
(EN) The presented dissertation thesis summarizes the new results of electrochemical generation of volatile compounds usable in atomic spectral methods. The main aim of this work is to develop and to characterize new types of electrolytic flow-through cells and to examine their possibilities of determination of arsenic, selenium and antimony by using the electrochemical hydride generation technique coupled with atomic absorption spectrometry with a quartz tube atomizer. Individual electrolytic cells were designed and constructed to comply with two important requirements. The cathode chamber of the electrolytic cell should have a minimal volume and a high efficiency of analyte conversion to the volatile hydride. Constructed electrolytic cells are divided into the construction groups and described in the experimental part. Selenium was chosen as the first analyte. The relevant working parameters (such as type, concentration and flow rate of electrolytes, generation current and carrier gas flow rate) were optimized for each newly constructed electrolytic cell. Under the optimal working parameters, the basic characteristics of selenium determination were found out by using electrochemical hydride generation. The electrolytic cells were compared to each other and with the classical electrolytic cell...
|
|
|
Laser Ablation of FOX-7: Proposed Mechanism of Decomposition
Civiš, Martin ; Rychlovský, Petr (referee)
A novel high-energy explosive material, FOX-7 (1,1-diamino-2,2-dinitroethylene), was studied using a combination of laser-induced breakdown spectroscopy (LIBS) and selected ion flow tube mass spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (an ArF excimer laser) as the energy source to convert small quantities of a sample into plasma and to induce the emission of its molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three reagent ions, with the ability to determine concentrations of trace gases and vapors of volatile organic compounds in real time. SIFT-MS was used to study the release of NO, NO2, HCN, HONO, HCHO, CH3CH2OH, and C2H2 after laser ablation of the explosive compound FOX-7 in solid crystalline form. The radiation emitted after excitation was analyzed using a time-resolved UV-vis spectrometerwith an ICCDdetector.The electronic bands ofCN(388nm),OH(308.4 nm), andNO(237.1 nm) radicals and the atomic lines of C, N, and H were identified.
|
|
|
Influence of interfering elements on the electrochemical selenium hydride generation
Vošmiková, Anna ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
This work is focused on the influence study of selected hydride forming elements (As, Sb), transition metals (Ni, Cu, Zn), anions (Cl- ,NO3 - ,SO4 - ) and cations (Ca2+ ,Na+ ), on the electrochemical hydride generation of selenium hydride. The analyte was converted to the volatile form and consequently atomized in a quartz tube atomizer. Atomic absorption spectrometer was used as a detection technique. For comparison, the same interference study was used to investigate for chemical hydride generation. The biggest influence on the analytical signal suppression was observed for other hydride forming elements at higher concentration (from 1mg/L of interfering elements the signal was suppressed by nearly 100 %). The transitions elements nickel and copper suppressed the analyte signal significantly. Neither selected anions nor cations suppress the signal significantly. No effect on the analytical signal was observed whet the sodium and calcium were tested at different concentration.
|
|
|
Optimization of conditions for gold determination using electrochemical generation technique with spectrometric detection
Jareš, Radek ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
This presented work is focused on the verification of basic experimental parameters of the electrochemical generation. The gold was was used as the analyte. One aim was to verified the optimal values of selected parameters of electrochemical generation (these parameters were concentrations of catholyte and anolyte and its flow rate, flow rate of carrier gas, atomization temperature, …). The other aim was to study the influence of different experimental arrangement (especially in construction of electrolytic cell and the cathode material) on the optimal values of working parameters and the basic characteristics of the gold determination. The tested cathode materials were lead, platinum and copper. In all cases, platinum was used as an anode material. The highest sensitivity of the gold determination was observed in the case of an electrolytic cell with a cathode and an anode consisting of platinum.
|
|
|
Sorption of radionuclid 85Sr to soils from area nuclear power plant Temelín
Reidingerová, Markéta ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
This thesis is focused on the study of sorption of radionuclide 85 Sr in soil collected in the area of a nuclear power plant Temelín. A single-batch method experiment was used when a solution of radionuclide 85 Sr of known activity was added to the soil. The experiments focussed on the influence of pH with the size of the sorption and the influence of the time of the contact of the solution with the sorption. During the experiment with the value of pH closest to the pH of underground water from the nuclear power plant Temelín, the sorption of soil was somewhere between 31 to 44 %. When the time influence on the sorption was examined, radionuclide 85 Sr was sorbed very quickly. For the comparison of the sorption size in connection with the time, for which it was chosen 120 minutes, the sorption was almost constant, reaching 40 to 48 %. Key words Radioactivity, radionuclide 85 Sr, sorption, nuclear power plant Temelín
|
|
|
Determination of Total Antioxidant Capacity in Select Food products and Dietary Supplements by Flow Injection Analysis with Chemiluminiscent Detection
Průchová, Karolína ; Rychlovský, Petr (advisor) ; Hraníček, Jakub (referee)
In this diploma thesis, a functional method for the determination of total antioxidant capacity by flow injection analysis with the chemiluminiscent detection was successfully developed. Luminol in carbonate buffer (composed of Na2CO3, NaHCO3 and (NH4)2CO3), with Cu2+ ionts as a catalyst, was used as a chemiluminiscent reagent. Chemiluminiscent radiation was induced by a diluted solution of hydrogen peroxide, a long-lasting chemiluminiscence was observed. First part of this thesis is dedicated to the optimalisation of the experimantal conditions for antioxidant capacity measurements as well as to the construction of apparatus for flow measurings. L-ascorbic acid was used as a standard. In the second part of this thesis the freshly developed method was used to determinate total antioxidant capacity of real food product simples, namely tea and coffee simples, beers, wines, chocolates, fresh fruit juices and selected food supplements. Results of this analysis were expressed as a vitamin C equivalent antioxidant capacity (VCEAC) related to standard, in mg/ml for liquid simples and in g/mg for solid simples. Results obtained are: tea simples 53 - 347 mg/1g of dried product, coffee simples 399-449 mg/g of dried product, beers 1,1-1,4 mg/ml, wines 4,2 - 4,8 mg/ml, fresh lemon juice 4,7 mg/ml, fresh kiwi juice 2,1...
|
guest ::
