National Repository of Grey Literature 24 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
The effect of selected compounds on determination of antimony by atomic fluorescence spectrometry with UV-photochemical generation of volatile compounds
Jelínková, Klára ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
5 Abstract This bachelor thesis is focused on the investigation of the influence of selected chemical individuals on the determination of antimony by UV-photochemical generation of volatile compounds with atomic fluorescence spectrometry detection (UV-PVG-AFS). Antimony, as a toxic semimetal occurring mainly in the trivalent and pentavalent oxidation state, plays an important role in many industries. Its determination is of importance not only from the point of view of analytical chemistry but also for monitoring of its environmental effects and for human health. For the interference studies with Sb5+ , the inorganic ions Br− , Cr2O7 2− , I− , CO3 2− , K+ , Cr3+ , Cd2+ , Co2+ , Cu2+ , Ni2+ , Na+ , Zn2+ , the organic solvents acetonitrile, ethanol and methanol, as well as the extraction reagents L-cysteine and 2-mercaptoethanol were chosen. Br− , Cr2O7 2− , I− , CO3 2− , K+ , Cr3+ , Cd2+ , Na+ and Zn2+ were chosen as possible interferents in the determination of Sb3+ . Solutions of the interferents were prepared in a medium of acetic acid (35%v/v) and 50 g l−1 Sb3+ or Sb5+ . The detection limit of the determination of Sb3+ in the flow injection mode analysis was 3.7 g l−1 for peak area and 1.9 g l−1 for peak height evaluation. For Sb5+ determination, the detection limit was 3.6 g l−1 for peak area and...
Compatibility of determination of antimony by UV-photochemical generation of volatile compounds and atomic fluorescence spectrometry with potential matrix components
Klečková, Adéla ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
The root of this bachelor work is UV-photochemical generation (UV-PVG) of volatile substances of antimony. Problematics, with which we deal, are potential interferences, which can affect measurement. As model interferents when considering future speciation analysis of antimony using HPLC-UV-PVG-AFS were chosen acetonitrile, methanol, ethanol, L-cysteine and 2-mercaptoethanol. Detection was progressed using atomic fluorescence spectrometry (AFS). L-cysteine muffled the response. Methanol and ethanol were behaving alike. They were increasing and lowering the peaks in waves, when only at the highest concentration they completely disappeared. Acetonitrile was proved to be the most interesting one thanks to its specifical behaviour, which started to show off in higher concentration. 2-mercaptoethanol had in smaller amount similar interference properties as acetonitrile.
Determination of cadmium by chemical vapour generation coupled with atomic fluorescence spectrometry
Štádlerová, Barbora ; Sagapova, Linda ; Musil, Stanislav
Development of a methodology for determination of cadmium based on chemical vapour generation coupled with atomic fluorescence spectrometry.
Determination of Mercury in Hair by Atomic Fluorescence Spectrometry
Šandlová, Petra ; Červený, Václav (advisor) ; Hraníček, Jakub (referee)
The functionality of PS Analytical's Millenium Merlin Satellite external module to the PSA Millenium Excalibur atomic fluorescence spectrometer has been demonstrated on real samples. Hair was selected as real samples. In the first part, several extraction procedures were tested to obtain the highest response. The best results were obtained by the extraction method with TMAH and HCl in FIA-UV-PVG- AFS mode. In the next part, an attempt was made to optimize the conditions for the separation of mercury speciation, namely Hg2+ and MetHg. The optimized parameters were: the percentage of organic component in the mobile phase, the pH of the mobile phase, the flow rate of the added mobile phase per column, and the flow rate of the added 0.050M HCl per column. After this stage, 3 more extraction procedures were tested: extraction using L-cysteine with HCl, extraction using PDTC and extraction using DEDTC. However, none of the extraction procedures was better than the extraction method with TMAH and HCl. Despite the optimization of the method, the speciation of Hg in the hair samples failed because the chromatograms obtained did not match (even in retention times) those obtained for the mixture of standards with the mobile phase extraction reagents. Subsequently, the conditions for the determination of total...
Development of Instrumentation and Methodology for Elemental and Speciation Analysis of Arsenic Based on Hydride Generation and on Atomic Fluorescence Spectrometric Detection
Marschner, Karel ; Dědina, Jiří (advisor) ; Kanický, Viktor (referee) ; Spěváčková, Věra (referee)
(EN) The presented dissertation is devoted to hydride generation from arsenic species and its application for speciation analysis based on atomic fluorescence detection. Hydride generation from toxicologically relevant arsenic species was optimized in order to achieve a 100% efficiency. The resulted experimental setup was subsequently used for speciation analysis of arsenic in human urine by high performance liquid chromatography with detection by atomic fluorescence spectrometry. The accuracy of the developed method was verified by comparative analyses of human urine samples collected from five individuals with an independent reference method. The cleavage of As-C bond during the reaction of methylated arsenic species with tetrahydridoborate(1-) (THB) in acidic media was studied in detail. Pronounced demethylation of methylated arsenic species was found during the reaction of THB with HCl, H2SO4, and HClO4 while hydride generation from CH3COOH or TRIS buffer after prereduction with L- cysteine resulted in the exclusive formation of the corresponding hydrides. Firstly, this phenomenon can endanger the accuracy of arsenic speciation which is based on hydride generation of substituted arsanes. Secondly, the more complex arsenic species can be converted to the hydride. That was demonstrated on hydride...
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...
Optimization of generation and atomization of arsines for speciation analysis by atomic fluorescence spectrometry
Marschner, Karel ; Dědina, Jiří (advisor) ; Komárek, Josef (referee)
Speciation analysis of arsenic based on selective hydride generation and detection by atomic fluorescence spectrometry have been studied in this work. It was found that under optimum conditions of atomization in the flame in gas shield atomizer, sensitivity was approximately twice higher and detection limit was about four times lower compared to miniature diffusion flame, which is a standard atomizer for atomic fluorescence spectrometry. The conditions to generate hydrides from both inorganic forms of the arsenic, i.e. from arsenite and arsenate, with the same efficiency have been found in the batch arrangement, by using 1 mol dm-3 hydrochlorid acid and 1% solution of tetrahydridoborate. To determine only trivalent form, TRIS buffer at pH 6.00 was used together with 1% sodium tetrahydridoborate. The detection limits found for inorganic arsenic, i.e. for arsenite and arsenate, respectively, were 15 ng dm-3 and 9 ng dm-3 . It was found that in the batch arrangement under these conditions it is possible to generate corresponding hydrides methylarsonate and dimethylarsonate with the same efficiency as from the inorganic form. Finally, it was found when slightly changing the gas-liquid separator design in order to introduce the mixture of tetrahydridoborate with hydrochloric acid to the bottom of the...
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.
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+ .
Chemical vapor generation of cadmium: detector comparison
Sagapova, Linda ; Štádlerová, Barbora ; Svoboda, Milan ; Kratzer, Jan ; Musil, Stanislav
A chemical vapor generation system was connected to an in-house assembled atomic fluorescence spectrometer (AFS) equipped with a miniature diffusion flame atomizer in order to assess its potential to Cd determination. Subsequently, analytical performance of three spectrometric detectors was compared (AAS, AFS, ICP-MS) with respect to Cd determination after volatile species generation.

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