National Repository of Grey Literature 69 records found  beginprevious60 - 69  jump to record: Search took 0.01 seconds. 
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.
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...
Tubular electrolytic cell for electrochemical generation of volatile compounds
Luštincová, Petra ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The newly constructed tubular flow-through electrolytic cell useful for electrochemical generation of volatile compounds was used in this presented work. The general aim of this work was to test several cathode materials to obtain the best basic characteristics of selenium determination by electrochemical hydride generation using the tubular electrolytic cell. The tested cathode materials were lead wire, lead/tin alloy (75 % of Pb and 25 % of Sn) and granulated lead. At first the optimizations of relevant working parameters were carrier out for all of these cathode materials. Under the optimal working parameters, the basic characteristics of selenium determination were found. The highest sensitivity (7.6 · 103 dm3 µg-1 ) and the lowest limit of detection (0.42 µg.dm-3 ) were obtained for granulated lead as cathode material. Subject words: Analytical chemistry Key words: Atomic absorption spectrometry, electrochemical generation of volatile hydrides, tubular electrolytic cell
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
Possibilities of electrochemical generation of volatile compound of silver
Linhart, Ondřej ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The presented bachelor thesis is to focus on the possibilities of electrochemical generation of volatile form of silver coupled with atomic absorption spectrometry which was used as a detection technique. The main aim was to optimize working parameters. A thin-layer electrolytic cell and a tubular electrolytic cell have been tested for the electrochemical generation of volatile form of silver. The optimization of appropriate electrolyte, its concentration and its flow rate, electric current and flow rate of carrier gas have been developed. Under the optimal working conditions the sensitivity of 0.029 dm mg-1 for the determination of silver by electrochemical generation was achieved.
Possibilities of electrochemical generation of volatile compound of gold
Průša, Libor ; Hraníček, Jakub (advisor) ; Musil, Stanislav (referee)
The possibilities of electrochemical generation of gold volatile compound have been studied in this work. All experiments have been employed in electrochemical continuous flow generation. The previous aim of this work was to investigate if it is possible to generate the volatile form of gold using electrochemical generation of volatile compounds. Lead, platinum and alloy of lead and tin were used as cathode materials. Consequently, optimizations of experimental conditions were carried out. The optimized experimental conditions were: carrier gas flow rate, flow rate of electrolytes, electric current used for electrochemical generation, influence of the different types of gas-liquid separator, atomizer temperature. The calibration and other characteristics were found. At the conclusion, effect of oxygen on the signal intensity was studied. Key words Electrochemical generation of volatile compound atomic absorption spectrometry quartz tube atomizer flow-through electrolytic cell volatile compound gold
Speciation analysis of chromium in particulate matter of urban dust
Rybínová, Marcela ; Hraníček, Jakub (referee) ; Rychlovský, Petr (advisor)
Anion-exchange chromatography with inductively coupled plasma - atomic emission spectrometry (ICP-AES) has been used for the speciation of chromium (Cr). Chromium speciation has attracted attention because of the different toxicity, Cr(III) is relatively non-toxic and Cr(VI) has been classified as a human carcinogen. The aim of the present study was to develop simple method for the speciation analysis of Cr (Cr(III) and Cr(VI)) in particulate matter of urban dust. A combination of 2% KOH + 3% Na2CO3 has been chosen as the optimal reagent for the extraction of chromium from particular matter. It was found that there was no conversion of Cr(VI) into Cr(III). The effect of separation parameters such as acidity of mobile phase was also studied. The detection limit for Cr(VI) was about 12 ng.ml-1 . Results for the determination of Cr(VI) were confirmed by the analysis of standard reference material (BCR CRM 545, Cr(VI) in welding dust loaded on a filter) with good agreement between certified (40,16 ± 0,60 μg.g-1 ) and found (37,83 ± 1,14 μg.g-1 ) values.

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