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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...
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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.
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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.
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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.
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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
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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...
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Determination of Low Concentrations of Cationactive Tenzides in Water Samples using Flow Injection Analysis Technique with Spectrofluorimetric Detection
Havelka, Michal ; Rychlovský, Petr (advisor) ; Červený, Václav (referee)
This thesis was focused on a development of sensitive determination of cationactive tenzides by using the flow injection analyses with spectrofluorimetric detection. The determination was based on an interaction of cationactive tenzides with sodium salt of 4,5,6,7-tetrachloro-2',4',5',7'- tetraiodofluorescein dye (Bengal red) that generates a soluble associate in water environs. The sodium salt of 4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein is a fluorescence-active compound. A decrease of fluorescence intensity is detected as a result of the formation of fluorescence-inactive associate. A development of the determination proceeded in two steps. At first a static method of the determination was developed. Cetyltrimethylammonium bromide (CTAB) and N-(α-karbethoxypentadecyl)trimethyl ammonium bromide (Septonex) were used as a standard for cationactive tenzides. An optimal theoretical concentration of Bengal red dye (5.10-5 mol/l) was found, an optimum rate of pH for the fluorescence of Bengal red dye (pH = 9) was found, and a suitable kind of buffer for the environs of the interactions (25 mM phosphate buffer) was found. A linear dynamic range for the determination (Septonex) was in the interval: the limit of quantification - 7.10-5 mol/l. The limit of quantification was 3,72.10-6 mol/l. Next...
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Study of Factors Influencing the Teduction of Rhenistane
Burešová, Helena ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
The aim of the bachelor thesis was to study the influence of conditions on the reduction of ammonium perrhenate by selected reduction agents. The amount of reduced perrhenate was followed by differential pulse voltammetry (as the decrease of the height of DPV peak). The percentage of reduced perrhenate was expressed as a function of molar ratio of the reduction agent to perrhenate. The following four agents were employed: sodium borohydride, hydroxylamine hydrochloride, hydrazine hydrochloride, and ascorbic acid. An amount of 97.8% of rhenium reduced was achieved by 0.9-fold of molar excess of sodium borohydride in 2 mol dm-3 perchlorid acid. The threefold molar excess of hydroxylamine hydrochloride reduced rhenium by 85% (in medium with pH = 8.5). The threefold molar excess of hydazine hydrochloride reduced rhenium by 68% (in medium with pH = 5.0). Ascorbic acid was the last studied reduction agent; its threefold molar excess reduced rhenium by 98.7%.
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Kinetic determination of nitrites with spectrophotometric detection
Vašíčková, Pavla ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
Title: Kinetic determination of nitrites with spectrophotometric detection Annotation: The proposal and optimization of the kinetic determination of nitrites in water samples is the aim of this bachelor thesis. The method is based on the ability of nitrites to catalyze the oxidation of toluidine blue by bromate in acidic media. The course of the reaction is monitored by spectrophotometrically, using a decrease of the absorbance band at 653 nm in the constant period of time from the beginning of the reaction. The dual-chanel manifolds FIA apparatus was proposed and optimized. The calibration dependency in the range of 0,05-1,00 mg ml-1 was measured. The instrumental limit of detection of 0,038 mg ml-1 and limit of quantification of 0,125 mg ml-1 were calculated. The method was applied on real sample of river water. Key words: nitrites, flow-injection analysis, kinetic catalytic methods
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Possibilities of electrochemical generation of volatile compound of thallium
Marschner, Karel ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
The possibilities of electrochemical generation of volatile thallium hydride have been studied in this work. A thin-layer electrolytic cell with minimal volume of cathode chamber has been employed. All experiments have been employed in electrochemical continuous flow generation. An electrochemical hydride generation technique was developed to improve the determination of analytes by atomic spectrometry. Effect of various experimental conditions such as kind of cathode material, type and concentration of electrolyte, amount of generation current and flow rate of carrier gas on the absorption signal was examined. Under the optimal values of previously mentioned parameters, the low sensitivity of thallium determination was achieved. So the experimental setup is not suitable for determination of low concentration of thallium in specimens. Keywords Atomic absorption spectrometry, electrochemical generation of volatile compounds, hydrides, thallium, electrolytic flow cell, optimization
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