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Interferences in determination of antimony by electrochemical generation of volatile compounds and atomic fluorescence spectrometry
Kostúrová, Dominika ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
Antimony is a highly toxic element that enters the environment through natural processes and human activities as well. It is necessary to determine its ultra-trace amounts in various materials such as water, soil and biological samples. Due to the heterogeneity of sample matrices, the determination of antimony is problematic because of frequent interactions. The aim of this work was to investigate the effects of various interferents on the determination of antimony by electrochemical generation of volatile compounds and atomic fluorescence spectrometry. In total, 18 interference dependencies were measured in the determination of Sb(III) and Sb(V). The following ions were selected for the interference study: SO4 2- , Cl- , NO3 - , NO2 - , Fe3+ , Fe2+ , As3+ , Se4+ and Bi3+ . The As3+ ion had the most interesting course of all the interferents and could be used as a suitable additive to increase the sensitivity of antimony determination.
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Spectrophotometric determination of stability constants of cyclodextrin derivatives by phenolphthalein method
Haiklová, Simona ; Dian, Juraj (advisor) ; Červený, Václav (referee)
This bachelor thesis deals with the determination of stability constants of cyclodextrins and their derivatives in the formation of supramolecular complexes with phenolphthalein. Cyclodextrins - macrocyclic oligosaccharides - are characterized by the shape of a truncated cone, whose internal hydrophobic cavity can form, with suitable substances, host-guest inclusion complexes. The formation of these inclusion complexes is accompanied by a change of a number of physicochemical parameters of the included compounds. In this bachelor thesis, the change of optical absorption of phenolphthalein, which has characteristic violet color in the alkaline area, was studied during its interaction with selected CD macrocycles. The formation of a supramolecular complex resulted in a decrease in optical absorption, which was quantified and used to determine stability constant. In the bachelor thesis, the supramolecular interaction of phenolphthalein with six derivatives of cyclodextrins were studied - basic cyclodextrins β-CD a γ-CD and their two derivatives. In the selected derivatives of these CDs the -OH groups in positions 2, 3, and 6 were replaced either by hydroxypropyl groups (hydroxypropyl-β-CD and hydroxypropyl-γ- CD) or (randomly) by methyl groups (RaMe-β-CD and RaMe-γ-CD). For these CD derivatives, the...
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Interferences in determination of antimony by UV-photochemical generation of volatile compounds and atomic fluorescence spectrometry
Kračmarová, Aneta ; Červený, Václav (advisor) ; Hraníček, Jakub (referee)
This work is focused on the study of interferents of selected elements during UV-photochemical generation of volatile antimony compounds. The interferents included transition metals, halides, hydride-forming elements and salts of mineral acids. Detection was performed by atomic fluorescence spectrometry. Some of the tested added substances proved to be potential reaction modifiers; in their presence, an increase in responses was observed. The best results were obtained using Fe3+ for the determination of Sb3+ and SO4 2- had the best results for the determination of Sb5+ . The largest interferent, i.e. the substance causing the most significant decrease in signal, was for both antimony ions Se4+ .
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Determination of calcium, copper, and lead in leaves by inductively coupled plasma-mass spectrometry
Plecháč, Matěj ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
V této práci byly stanovovány koncentrace vápníku, mědi a olova ve vzorcích listů pomocí metody ICP-MS. Vzorkovaný materiál pocházel z různých míst České republiky a jednalo se o listy různých druhů stromů. Vzorky listů byly sušeny a poté rozloženy v mikrovlnném rozkladném zařízení za přítomnosti koncentrované kyseliny dusičné. Ve výsledcích bylo prokázáno, že koncentrace kovů se liší podle lokality sběru a v rámci jedné lokality byly různé u listů jednotlivých rostlinných druhů. Stanovené koncentrace vápníku se pohybovaly v rozmezí 5,6 - 30 mg/g a její průměrná koncentrace byla 14 mg/g. Koncentrace mědi byla v rozmezí 4,3 - 18 µg/g a její průměrná koncentrace byla 9,91 µg/g. Koncentrace olova byla v rozmezí 0,19 - 3,2 µg/g a jeho průměrná koncentrace byla 0,79 µg/g. V této práci bylo také ověřeno, že zvolený postup přípravy vzorků byl vhodný pro analýzu vzorků listů na ICP-MS, a že metoda ICP-MS byla díky nízkým limitům detekce vhodná pro stanovení koncentrací všech vybraných kovů.
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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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Derivatization of the micro-samples of natural polymers with similar composition for FTIR analysis
Dudičová, Dorota ; Červený, Václav (advisor) ; Dian, Juraj (referee)
in English This master thesis is focused on verifying the possibility of optimizing FTIR spectrometric analysis of terpenic resins using derivatized (fluorinated) samples using XtalFluor-E in combination with triethylamine trihydrofluoride as an agent. Terpenic resins have very similar FTIR spectra, so for their better differentiation, they need to be derivatized to minimize the influence of overlapping spectral bands in FTIR spectra. This work aimed to create a methodology for derivatization of samples of natural polymers for the National Technical Museum in Prague, where the work was performed. Samples of terpenic resins were measured non-fluorinated by the ATR crystal method and by transmission, after fluorination, only the ATR crystal method was used. Different fluorination conditions, different times (2, 4, 6, 24 and 96 hours), the effect of sample rinsing (diethyl ether, ethylene tetrachloride) and the effect of matrix on the sample (KBr pellet) were tested. Fluorination has shown to be effective. Four hours of fluorination and the need to rinse the sample with diethyl ether were chosen as the optimal fluorination conditions. After testing the resins themselves, fluorinated samples of violin varnishes and samples of historical varnishes from harp and piano were analyzed. Their spectra before...
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Study of properties of UV-photochemical generation of volatile compounds od antimony
Adámková, Dominika ; Červený, Václav (advisor) ; Hraníček, Jakub (referee)
The master thesis deals with comparison of atomic fluorescence spektrometry and high resolution continuum source atomic absorption spektrometry for three methods generation of volatile compounds Antimony. In both methods of atomic antimony detection, it compares the most common chemical generation of volatile compounds (hydrides) with two alternative methods - electrochemical and UV - photochemical. The values of performance parameters for the determination of Sb(III) and Sb(V) were determined for all the above combinations. In the case of chemical generation, a surprisingly almost four times higher limit of detection of Sb(III) was found in connection with AFS detection than AAS detection. The final part was devoted to UV - photochemical vapor generation, with AAS detection for Sb(III) reaching limit of detection 4,96 ppb, for Sb(V) 8,63 ppb. Although UV - photochemical generation of volatile antimony compounds did not reach such performance parameters as chemical or electrochemical generation, it was observed that the sensitivity of antimony determination increased greatly when introducing oxygen into the apparatus. The interference study also found a significant positive effect of Fe(II) on the generation efficiency, and this modification partially persisted without further introduction of these...
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Determination of lead and cadmium in fruits and vegetables extracts by atomic absorption spectrometry
Záškodová, Terezie ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The content of this thesis was to analyse fruit and vegetable extracts. In the samples, the concentration of lead and cadmium was determine by atomic absorption spectrometry. First, it was necessary to conduct an optimalization study to find the optimal conditions of the method and select the appropriate method of atomization of the sample. It was chosen between flame and electrothermal atomization. For optimization, the following parameters were studied for atomization in flame: beam height above the burner, fuel flow rate, horizontal burner position, spectral interval width and lamp supply current. An optimization study for electrothermal atomization included the effect of atomization a pyrolysis temperature on signal size. Standard lead and cadmium solutions were used to determine the detection limits of the instruments used. The limit of detection in flame atomization was for lead respectively cadmium 0,002 mg/l, resp. 0,003 mg/l. In electrothermal atomization the detection limit was for lead, resp. cadmium 0,026 μg/l, resp. 0,029 μg/l. The experimentally determined values were statistically processed and the lead and cadmium contents were compared with the lead and cadmium limit values that may be contained in a sample of fruit and vegetables according to Commission Regulation (EC) No...
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Comparison of mercury determination by electrochemical or UV-photochemical vapor generation with detection by atomic fluorescence
Šandlová, Petra ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
~ 5 ~ Abstract The functionality of the add-on Millennium Merlin Satellite module towards the PSA Millennium Excalibur atomic fluorescence spectrometer for determination of mercury has been proven. At the same time, the ratios of the average signal to the sample standard deviations of the results of repeated measurements of this module were compared with the mercury determination using an atomic absorption spectrometer ContrAA700 with a radiation source with continuous spectrum and high resolution. In model experiments performed on an atomic absorption spectrometer, the experimental conditions of the cold vapor detection above the level of the elemental mercury were optimized. The flow rate of argon and hydrogen, the temperature of the detection cell and the storage bottle and the mercury evaporation time were optimized. It has been shown that the reduction environment in the detection tube reduces the signal. The need to heat the detection tube up to 650 řC has been surprising. The causes of this phenomenon were discussed and confronted with data from the available literature. Subsequently, the mercury signal was monitored unde roptimal conditions found on the AAS, using an atomic fluorescence PSA Millennium Excalibur spectrometer with an additional Millennium Merlin Satellite unit for mercury...
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