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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
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The comparison of methods for determination of ascorbic acid in medical formulations
Kohoutová, Petra ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
The aim of this thesis is to compare and assess chosen analytical methods for ascorbic acid determination in pharmaceuticals with respect to their correctness, accuracy, time and finance exigencies. Four methods were chosen alkalimetric titration with visual and instrumental indication, iodometry and spectrophotometry. Pills, capsules and injection solution were chosen as samples of pharmaceuticals. The obtained results as to accuracy of the declared value (or range permitted under Pharmacopoeia) agreed by all titration methods, spectrophotometric determination showed overestimated results. All used methods were approximately equally accurate. As time seems to be most optimal acidobasic titration with visual indication, while demanding in terms of time was spectrophotometry. If we consider methods on financial intensity all titration methods were quite equal.
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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.
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The Speciation Analysis of the Toxicological Important Forms of the Arsenic in Urban Particulate Matter Samples with the Detection QF-AAS
Jelínek, Petr ; Rychlovský, Petr (advisor) ; Červený, Václav (referee)
The topic of this diploma thesis was the speciation analysis of the toxicological important forms of the arsenic in urban particulate matter samples. The detection technique used in this work was atomic absorption spectrometry with quartz atomizer. Acetic acid, ammonium acetate, hydroxylamine, potassium hydroxide and sodium carbonate are recommended leaching agents for extraction of metals from urban particulate matter samples. Results of the presenting work are following: Acidic extraction reagents can be not recommended for the speciation analysis of the arsenic, because these reagents lower sensitivity of the determination of As3+ and As5+ too and destroy the quartz atomizer. Alkaline extraction reagents don't lower sensitivity of the determination of As3+ and these reagents don't destroy the atomizer, but lower sensitivity of the determination of As5+ was obtained. Recommended reagents aren't useful for extraction of the metals from urban particulate matter samples for the speciation analysis.
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Novel Approaches to the Application of Electrochemical Volatile Compounds Generation in Spectrometric Methods
Červený, Václav
Various possibilities for the use of electrochemical generation of volatile compounds for the determination of trace and ultratrace quantities of elements using atomic absorption spectrometry and optical emission spectrometry, respectively, were studied in this work. The Thesis is divided into four thematic sections. Electrochemical cold mercury vapor generation is common to the first two parts. The third part is devoted to electrochemical generation of the volatile form of cadmium and the last part deals with the use of the electrochemical hydride generator as a derivatization unit for speciation analysis of arsenic compounds. The optimization of each individual determination was carried out including, for example, various designs of the generator of volatile compounds (forms) of the analyte, the changes in the design of the gas-liquid separator, optimization of the concentration and the flow rate of all the solutions and the carrier gas. However, the value of the electric current employed was the most important parameter. In the first section, the in-situ trapping system of the cold mercury vapor generated in the graphite furnace (with the inner surface covered with a gold foil) of the atomic absorption spectrometer was also designed and optimized. The absolute limit of detection, 80 pg, was...
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Comparision of methods for sulphide determination
Zlámalová, Magda ; Červený, Václav (referee) ; Nesměrák, Karel (advisor)
The aim of this work is determination of sulphides in a solution by suitable methods and it's subsequent comparison from a point of view to the precision, financial and time demands. Iodometric titration, argentometric titration, and potassium ferricyanide titration were chosen for the determination of sulphides in the solution. Anhydrous sodium sulphide and sodium sulphide hydrate were used as model samples. From the point of view to financial and time demands the most advantageous method was potassium ferricyanide titration and the least advantageous method was iodometric titration. The precision of used methods was dependent on type of used sample. Iodometry was the least precise determination of sulphides in the sample of anhydrous sodium sulphide; the precision of argentometry and potassium ferricyanide titration was comparable. Potassium ferricyanide titration was the most precise determination of sulphides in the sample of sodium sulfide hydrate; the least precise determination was argentometry.
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