|
|
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...
|
|
|
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%.
|
|
|
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
|
|
|
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
|
|
|
Spectroelectrochemical cell with CD-trode
Hladík, Martin ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
This bachelor thesis was aimed on the optimisation of preparation of gold electrodes (CDtrodes) from commercially available DVDs by treatment of concentrated nitric acid. The duration of the treatment was set on 20 minutes, based on study of voltammetric responses of fabricated CDtrodes. The CDtrodes were employed in spectroelectrochemical cells in two arrangements (i) with beam perpendicular to the area of electrode, and (ii) with beam collinear to the area of electrode. The formation and extinction of phenothiazine radicals during cyclic voltammetry were followed spectrophotometrically. Key words: spectroelectrochemistry, CDtrode, phenothiazine
|
|
|
Contributions to Volatile Compound Generation of Arsenic, Silver and Gold by Tetrahydroborate Reaction for Atomic Absorption Spectrometry
Musil, Stanislav ; Rychlovský, Petr (advisor) ; Kanický, Viktor (referee) ; Spěváčková, Věra (referee)
(EN) The presented dissertation thesis summarizes the results contained in five original research papers that were published in prestigious international scientific journals in the field of analytical chemistry and atomic spectrometry. It is devoted to the method of generation of volatile compounds using a tetrahydroborate reaction and detection in a quartz multiatomizer by atomic absorption spectrometry. The thesis can be divided into two thematic parts - speciation analysis of arsenic based on hydride generation technique with collection and separation in a cryogenic trap and generation of volatile species of transition metals. In the first thematic part pre-reduction of pentavalent inorganic and methylated arsenicals has been studied. A simple setup for on-line pre-reduction employing thioglycolic acid as a fast pre-reductant has been developed, connected with a current hydride generator and applied/verified to oxidation state specific arsenic speciation analysis of human urine samples. In the same method the possibility of drying the gaseous phase from water vapor has been investigated to avoid incidental blocking the cryogenic trap by frozen water and to decrease fluctuations of signal baseline. Pronounced losses of methylated species have been discovered on Nafion tube dryer currently used in...
|
|
|
Speciation analysis of selenium compounds
Kramulová, Barbora ; Rychlovský, Petr (advisor) ; Šíma, Jan (referee)
Previously, selenium was known as an element with negative properties. However, in the last century, the significant positive effects on human health were detected. Currently, the function, behavior and toxicity of selenium are still not well known. The key to understand it is to do speciation analysis. The aim of this diploma thesis is to develop method for determination inorganic (sodium selenite and selenate) and organic (selenourea, selenocystine, selenomethionine) selenium compounds. Parameters of apparatus for electrochemical hydride generation with atomic absorption spectrometry detector were optimized, final conditions were set and optimal conditions for separation process using HPLC were investigated. Calibration dependences for selenium compounds were measured and analytical figures of merit were investigated. In conclusion, a coupled method HPLC- EcHG- QFAAS for determination of individual selenium compounds was proposed, and it was tested on urea samples. Calibrations for these measurements were investigated and analytic characteristics were calculated. Based on these comparisons it can be said that proposed method allows the determination of selected selenium compounds in both aqueous and urea matrices. Subject words: Spectroscopy, analytical chemistry Key words: Atomic absorption...
|
|
|
Determination of heparine by SIA with spectrofluorimetric detection
Bár, Ladislav ; Rychlovský, Petr (advisor) ; Nesměrák, Karel (referee)
This thesis was focused on a determination of heparin using sequential injection analysis with spectrofluorimetric and spectrophotometric detection. The principle of determination was based on the interaction of heparin with phenothiazine dye. A decrease of fluorescence intensity of dye in its emission maximum was detected. In the case of spectrophotometric detection a decrease of the absorbance of dye was measured. Azure A, azure B and methylene blue were used as representantive selection of phenothiazine dyes. The determination was performed on a laboratory made SIA apparatus, for which a control software in LabVIEW 7.1 graphical programming was created. Two types of flow configuration for spectrofluorimetric detection were implemented. Type 1: For deionized water as a carrier stream with a injection of heparin and dye zones there were found the following optimal conditions: cdye = 1×10-5 mol dm-3 ; vflow = 2500 µl min-1 ; reaction coil length of 0 cm; injected volume of dye 150 µl and injected volume of sample 150 µl. Dynamic range of calibration curves with an exponential course for the individual dyes in the range of LOQ - 1200, eventually up 1500 IU dm-3 were detected. Limits of detection between 7.6 - 39.1 and the limits of quantification between 58.8 - 124.5 IU dm-3 were found. Type 2: For...
|
|
|
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.
|
|
| |
guest ::
