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1
Furdíková, Zuzana. "Studium generování, záchytu a atomizace těkavých hydridů pro metody atomové spektrometrie." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-233290.
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Interference effects of co-generated hydrides of arsenic, antimony, bismuth and selenium on trapping behavior of selenium or antimony hydrides (analytes) within iridium modified, transversely heated graphite tube atomizer (THGA) was investigated. A twin-channel hydride generation system was used for independent separate generation and introduction of analyte and interferent hydrides, i.e. in simultaneous and/or sequential analyte-interferent and interferent-analyte mode of operation. Influence of the analyte and modifier mass, interferent amount, trapping temperature and composition of the gaseous phase was studied. A simple approach for elimination of mutual interference effects by modification of the gaseous phase with oxygen in substoichiometric ratio to chemically generated hydrogen is proposed and suppression of these interference effects is demonstrated. A hypothesis on mechanism of trapping and mutual interference effects is drawn.
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Krejčí, Pavel. "Studium miniaturních zařízení pro kolekci hydridotvorných prvků v atomové spektroskopii." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233325.
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Capability of a prototype of miniature collection device based on a strip of the molybdenum foil for collecting hydride forming elements (As, Se, Sb and Bi) was studied. The device was combined with a miniature hydrogen diffusion flame for detection by atomic absorption spectrometry. The conditions for trapping and subsequent vaporization of analytes of interest were optimized. A twin-channel hydride generation system was used for study of mutual interference effects of co-generated hydride forming elements. The influence of modification of the molybdenum surface with noble metals - Rh, Pt and Ir on trapping and vaporization processes was also studied and changes of microstructure of the foil surface after modification were investigated using scanning electron microscope equipped with energy dispersive x-ray analyzer and electron backscattered diffraction system. Complementary radiotracer and radiography experiments were performed in order to determine trapping efficiency and to assess the spatial distribution of collected analytes within the device. Practical application of the method was demonstrated on determination of antimony in water samples at trace level. Possibility of multi-element analysis was demonstrated by combining the collection device with atomization and excitation of the analyte in microwave induced plasma and with detection by atomic emission spectrometry method. The results of the experiments proved that tested miniature collection device is capable of trapping analytes that form volatile hydrides. This device can be coupled to various types of atomizers, typically used in spectrometry methods. Thus, very sensitive and specific detection of hydride forming elements can be performed.
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Resslerová, Tina. "Elektrochemické generování hydridů telluru a bismutu s detekcí AAS." Master's thesis, 2014. http://www.nusl.cz/ntk/nusl-338160.
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Tellurium and bismuth are non-biogenous elements, which can be accumulated in human body. The aim of this work is focused on the determination of these elements by the electrochemical hydride generation with non-membrane electrolytic cell with quartz tube - atomic absorption spectrometry. The first step of the work was to optimize parameters for the continuous setup measurements and to obtain its figures of merit. After this, the arrangement with most suitable conditions for determination of these elements was converted to the flow injection setup (FIA) and all experimental parameters were again optimized and its figures of merit were obtained. The conditions of hydride generation were studied for platinum, lead and silver cathodes with hydrochloric and sulphuric acids and their sodium salts as electrolytes. The optimizations of the FIA setup were performed on platinum cathode in hydrochloric acid for bismuth and on lead cathode in sulphuric acid for tellurium. The limit of detection achieved for the generation of tellurium hydride was 1.1 ppm with a linear range up to 20 ppm; for the bismuth hydride the limit of detection was 9.5 ppm and limit of linearity 50 ppm. Keywords Bismuth, tellurium, electrochemical hydride generation, atomic absorption spectroscopy, flow injection analysis
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Svoboda, Milan. "Generování hydridů pro speciační analýzu arsenu atomovou absorpční spektrometrií." Master's thesis, 2006. http://www.nusl.cz/ntk/nusl-374458.
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Bufková, Kateřina. "Generování hydridu telluru pro atomovou absorpční spektrometrii." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-397553.
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This master's thesis deals with optimization of conditions of chemical hydride generation of tellurium and conditions of its atomization, specifically in three types of atomizers - in a diffusion flame (DF), in a heated multiple microflame quartz tube atomizer (MMQTA) and in a dielectric barrier discharge (DBD) atomizer. Tellurium hydride was generated in a flow injection arrangement and a high-resolution continuum source atomic absorption spectrometer was used for detection. As hydride generation can be only done from tetravalent species of tellurium, at first a simple procedure of pre-reduction of hexavalent species of tellurium by heating a standard in hydrochloric acid at 6 mol dm-3 was verified. Further, conditions of chemical generation were optimized with a goal to achieve as high generation efficiency as possible, namely, concentration of hydrochloric acid and sodium tetrahydroborate, volume of the reaction coil and a flow rate of carrier gas. Subsequently, conditions of atomization of tellurium hydride were examined with chosen optimal generation conditions. In the case of DF, it was an amount of hydrogen in the flame, a total flow rate of gases and observation height. In the case of MMQTA, temperature of the atomizer, a flow rate of carrier gas and a flow rate of air or oxygen needed for...
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Bradyová, Michaela. "Rozvoj postkolonového generování hydridů pro analýzu glutathionových komplexů arsenu pomocí HPLC-(HG)-ICP-MS." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-333299.
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This thesis develops high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-HG-ICP-MS) method used for the analysis of glutathione arsenic complexes in biological samples. The aim of the thesis was to verify the suitability of this methods and to perform pilot studies on analysis of the enzymatic methylation assay containing glutathione and urine. Inclusion of post-column hydride generation step resolves the problem of changing sensitivity of ICP-MS with gradient elution. Using the standards of glutathione complexes, it was verified that the HPLC-HG-ICP-MS method can provide both qualitative and quantitative analysis of these complexes. The limit of detection was found at 5 pg/ml. Analysis of the methylation assay of arsenic with glutathione showed that only DMAsGS complex occurs in the assay during methylation. It was verified that the presence of the enzyme is required for the complex formation. In the samples of urine from unexposed people analyzed by HPLC- HG-ICP-MS and hydride generation-cryotrapping-inductively coupled plasma mass spectrometry (HG-CT-ICP-MS), only the presence of free pentavalent arsenic species was found, whereas neither glutathione complexes nor trivalent species could be observed.
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Svoboda, Milan. "Studium generování hydridů pro účely speciační analýzy arsenu spojené s AAS a AFS detekcí." Doctoral thesis, 2012. http://www.nusl.cz/ntk/nusl-330387.
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The general aim of this work was a development of methodology and instrumentation for speciation analysis based on the combination of the selective generation of substituted hydrides with atomic absorption or atomic fluorescence spectrometry detection. The first topic of this work was the development of methodology and instrumentation for arsenic speciation analysis based on selective generation of substituted arsines with trapping in the cryogenic trap (U-tube packed with chromosorb) with AAS detection (HG- CT-AAS). The conditions of the selective hydride generation approach as well as working procedure of the cryogenic trap were optimized (appropriate approach for hydride generation, set up of heating program of cryogenic trap, new dryer - cartidge with NaOH, elimination of unspecific absorption, decreasing of the detection limits). The second important part of the work lay in applying of the developed method for arsenic speciation analysis in a homogenized mouse liver tissue. The direct slurry sampling to hydride generator was develop. Moreover the information about oxidation state (iAsIII,V , MAsIII,V a DMAsIII,V ) was obtain. The effect of relevant experimental parameters such as tetrahydroborate concentration, TRIS buffer concentration and time of pre-reduction of the samples by L-cysteine...
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Vyvadilová, Tereza. "Příspěvek k optimalizaci parametrů speciační analýzy As založené na selektivním generování hydridů v uspořádání přímého přenosu hydridů s detekcí atomovým absorpčním spektrometrem." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-324212.
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The presented thesis deals with optimization of parameters speciation analysis based on a selective hydride generation in a direct transfer mode of hydrides and on-line atomization in an atomic absorption spectrometer. In the first part of the thesis processes during generation were investigated. Important indicator of a reactions taking place in a generator is volume of hydrogen (created by decomposition of NaBH4) which is subsequently introduced to the atomizer. In this part of the thesis a new approach to determine a flow rate of hydrogen delivered to the atomizator was developed. An influence of relevant paremeters of the atomizers and atomic absorption spectrometers on basic analytical characteristics of arsenic determination based on hydride generation was performed in the second part. Three atomic absorption spectrometers were used and three sources of radiation were compared. The most important analytic characteristic was the limit of detection which is influenced by standard deviation of measurement values of blank samples and by sensitivity. The best values of the limit of detection were achieved with electrodeless discharge lamps. Key words: hydride generation, arsenic, speciation analysis, atomic absorption spectrometry
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Štádlerová, Barbora. "Optimalizace podmínek atomizace hydridů bismutu, olova a cínu pro účely vývoje atomizátorů hydridů." Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-380366.
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This Master thesis is a part of a project: Hydride atomizers for atomic absorption and atomic fluorescence spectrometry - new horizons (GA ČR, P206/17-04329S, principal investigator: prof. RNDr. Jiří Dědina, CSc. DSc.) of which the general target is to make a leap towards the ideal hydride atomizer by optimization of atomization based on the knowledge of the distribution of free atoms and hydrogen radicals inside the atomizers. This thesis contributes to the project by optimizing the atomization parameters for atomic absorption spectrometry with hydride generation. The atomization parameters were optimized for three different types of atomizers - multiatomizer, diffusion flame and "flame-in-gas-shield" atomizer using three different analytes - bismuth, lead and tin. Optimal atomization parameters were found for each of the atomizer and each of the analyte - carrier gas flow and flow of other gases if needed for the analysis. Calibration curves and analytical figures of merit such as sensitivity, LOD and LOQ were estimated. Final comparison is based on the data obtained from calibration curves. MDF and FIGS atomizers are mostly used with AFS detection and they provide lower sensitivity and higher detection limits with AAS detection in comparison with MMQTA. Since the analytes are known to trap...
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Marschner, Karel. "Optimalizace podmínek generování a atomizace arsanů pro speciační analýzu metodou atomové fluorescenční spektrometrie." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-324639.
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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...
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Pokorná, Nikola. "Stanovení specií arsenu v referenčních materiálech mořského původu metodou ICP-MS s generováním hydridů a vymrazováním." Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-380365.
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The aim of this work was to determine chemical species of arsenic in sea originating certified reference materials. Measurements were done using method of hydride generation. Hydrides were preconcentrated in liquid nitrogen cooled tube and detected using inductively coupled plasma mass spectrometry. During the testing of the method, mutual conversion of arsenic species was observed for inorganic arsenic, monomethyl arsenic and dimethylarsenic. Further study revealed that with presence of matrix and hydrogen peroxide, demethylation occured only in hydride generation phase, not during extraction. Dissociation of hydrogen peroxide in extracts was verified using catalase. End of the demethylation process was proved using measurement with addition of arsenic species standards. The newly invented procedure was used to determine arsenic species in reference materials with sufficient accuracy. Final results are compatible with results from different method, and already published results as well. Key words: speciation analysis, arsenic, hydride generation, seafood, inductively coupled plasma mass spectrometry
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Trojánková, Nikola. "Speciační analýza toxikologicky významných forem arsenu: rozvoj a porovnání technik využívajících generování těkavých hydridù, s detekcí ICP MS." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-304831.
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Nowadays, arsenic is becoming an important pollutant in the environment. Chronic exposure to arsenic can cause number of serious diseases. Therefore, a development of analytical methods for trace and ultratrace speciation analysis- analysis of individual forms or phases in which As is found in the sample - is fully in place. This Thesis compares four methods of trace speciation analysis, with focus on limits of detection and quantification, and on comparison of results of analysis of river and sea water reference materials. Methods based on hydride generation with preconcentration by cryotrapping and AAS or ICP-MS detection, with limits of detection in ng or tenths of ng·dm-3 , are compared with procedures employing HPLC, with ICP-MS detection. The Thesis includes development and optimization of a pre-reduction step of postcolumn hydride generation with on-line pre-reduction of pentavalent arsenic species, in order to improve sensitivity of this method. Limits of detection around 10 ng·dm-3 are achieved. The results of analyses obtained by individual methods are in excellent agreement. Keywords: Arsenic, speciation analysis, hydride generation, atomic absorption spectrometry, inductively coupled plasma- mass spectrometry, high efficiency liquid chromatography, limits of detection.
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Marschner, Karel. "Vývoj instrumentace a metodologie pro prvkovou a speciační analýzu arsenu založenou na generování hydridů a na detekci atomovou fluorescenční spektrometrií." Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-369450.
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(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...
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Kolrosová, Marta. "Generování hydridu bismutu pro atomovou absorpční a fluorescenční spektrometrii." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-397522.
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This master's thesis deals with the optimization of conditions of chemical hydride generation (HG) of bismuth, its atomization and detection by atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). Two types of atomizers were used for atomization of volatile species, a miniature diffusion flame for AAS as well as for AFS and a flame-in-gas-shield atomizer for AFS. At first, the parameters of HG in a flow injection mode were optimized - the concentration of hydrochloric acid, the concentration of sodium borohydride and the volume of the reaction coil. Subsequently, the atomization conditions were optimized using both atomizers. The parameters optimized were hydrogen fraction, total gas flow rate and observation height. Due to the more complicated construction of the FIGS atomizer, more parameters were studied, such as the oxygen flow rate through the capillary and the flow rate of shielding argon required for shielding the free atoms. A special part of the thesis dealt with the optimization of the optical path of the atomic fluorescence spectrometer, the selection of an interference filter and the optimization of a power supply of an electrodeless discharge lamp. It was found that under optimum conditions of generation, atomization and detection excellent detection limits...
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Taurková, Petra. "Mineralizační metody pro speciační analýzu toxikologicky významných forem arsenu v tkáních pomocí generování hydridů s kolekcí vymrazováním a atomové absorpční spektrometrie." Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-280620.
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This diploma thesis develops methodology of arsenic speciation analysis by selective hydride generation with cryotrapping and atomic absorption spectrometry. Using this technique it is possible to determine toxicologically important forms of arsenic, i.e arsenites, arsenates and their mono-, di-, and trimethylated forms at concentration levels below 0,1 ng.ml-1 . The first part of the thesis is focused on testing tubular membrane gas dryers with nafion membrane for drying gaseous phase containing generated hydrides. The suitability for arsenic speciation analysis was investigated and transport losses of individual arsenic species were found. The second part describes mild digestion procedures suitable for arsenic speciation analysis in tissues. Two procedures were compared, acid digestion in phosphoric acid and more recent alkalic digestion by tetramethylammonium hydroxide. Digestion procedures were tested on certified reference material DOLT - 4 (Dogfish Liver) and chicken liver matrix. Key words: Tubular nafion membrane dryers, Arsenic speciation analysis, Digestion, Phosphoric acid, Tetramethylammonium hydroxide, Chicken liver, CRM DOLT - 4, Hydride generation, Atomic absorption spectrometry
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Jelínek, Petr. "Speciační analýza toxikologicky významných forem arsenu v polétavém prachu s detekcí QF-AAS." Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-296652.
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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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Juhászová, Lucie. "Mechanismus atomizace vybraných hydridotvorných prvků ve vyhřívaném křemenném atomizátoru a plazmovém atomizátoru s dielektrickou bariérou." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-397505.
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Atomization conditions for tin hydride in the planar dielectric barrier discharge (DBD) plasma atomizer were optimized with detection by atomic absorption spectrometry (AAS). The effects of apparatus arrangement such as the shape of a waveform function of the high voltage power supply source, DBD atomizer design as well as presence of a dryer tube filled with NaOH pellets to prevent residual aerosol and moisture transport into the DBD were investigated in detail. The optimal experimental setup consisted of a square wave high voltage power supply source coupled to a DBD with vapor-deposited electrodes in the presence of NaOH dryer upstream the DBD atomizer. Argon was found as the best discharge gas under a flow rate of 120 mL min-1 while the DBD optimum high voltage supply rate was 7 kV. A sensitivity of 0.05 s ng-1 Sn and a limit of detection of 1.1 ng mL-1 Sn were reached under optimized conditions. Optimization of the whole experimental setup resulted in 7-fold improvement of sensitivity compared to the original arrangement consisting of a sinusoidal source coupled to a DBD atomizer with glued electrodes in absence of the dryer. Keywords atomic absorption spectrometry, hydride generation, hydride atomization, quart tube atomizer, dielectric barrier discharge (DBD)
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Duben, Ondřej. "Stanovení selenu metodou HG-AAS s prekoncentrací a atomizací v plazmovém výboji s dielektrickou bariérou." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-342936.
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The aim of this thesis was to optimize atomization conditions for selenium hydride in a novel plasma atomizer based on dielectric barrier discharge (DBD) using atomic absorption spectrometry as a detector. Analytical characteristics have been subsequently determined and compared to those reached in a conventional externally heated quartz tube atomizer which was replaced by a sofisticated design of a multiatomizer (MMQTA) in this work. The limit of detection reached in DBD (0,24 ng ml−1 Se) is slightly worse to that observed in MMQTA (0,15 ng ml−1 Se). On the contrary, slightly better resistance towards interferences of Sb, Bi and As was observed in DBD atomizer in comparison with MMQTA. Possibility of selenium preconcentration in a DBD atomizer was studied reaching an overall preconcentration efficiency of 75 ± 5%. The detection limit in a preconcentration mode employing preconcentration period of 300 s has reached 0,012 ng ml−1 Se. Key words: hydride generation atomic absorption spectrometry, dielectric barrier discharge, hydride atomization, hydride trapping, selenium
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Albrecht, Michal. "Analýza nestabilních komplexů pro studium enzymatické methylace arsenu." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-405297.
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The main aim of this thesis was the development of conjugation of existing methods for analysis of arsenic-glutathione complexes (As-GS complexes) together with simple arsenic species (iAs, MMAs, DMAs) during simple run. The basic technique for analysis of As-GS complexes was the HPLC-ICP-MS method with a reverse phase separation column (C18). The separation problem of simple species has been overcome by extending of system by postcolumn hydride generation with cryotrapping system (HG-CT). The resulting HPLC/HG-CT-ICP-MS system provides a complex analysis of all the above-mentioned analytes. According to the currently available resources, it is an innovative system, where for the first time all the simple arsenic species (iAs, MMAs, DMAs) and the As-GS complexes were separated. Under the given conditions, the detection limit for the As-GS complexes of 1.9 pg cm-3 in the RP-HPLC-ICP-MS system (a quantification limit of 6.5 pg cm-3 ) was achieved at a sensitivity of 468 CPS s pg-1 . The HG-CT-ICP-MS system provided a detection limit for iAs of 1.2 pg cm-3 at a sensitivity of 1121 CPS s pg-1 , for MMAs of 0.043 pg cm-3 at a sensitivity of 895 CPS s pg-1 and for DMAs of 0.076 pg.cm-3 at a sensitivity of 926 CPS s pg-1 . This method was applied to achieve another aim, studying the pathways of enzymatic...
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Hraníček, Jakub. "Konstrukce miniaturních průtokových cel pro elektrochemické generování těkavých sloučenin." Doctoral thesis, 2011. http://www.nusl.cz/ntk/nusl-312116.
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(EN) The presented dissertation thesis summarizes the new results of electrochemical generation of volatile compounds usable in atomic spectral methods. The main aim of this work is to develop and to characterize new types of electrolytic flow-through cells and to examine their possibilities of determination of arsenic, selenium and antimony by using the electrochemical hydride generation technique coupled with atomic absorption spectrometry with a quartz tube atomizer. Individual electrolytic cells were designed and constructed to comply with two important requirements. The cathode chamber of the electrolytic cell should have a minimal volume and a high efficiency of analyte conversion to the volatile hydride. Constructed electrolytic cells are divided into the construction groups and described in the experimental part. Selenium was chosen as the first analyte. The relevant working parameters (such as type, concentration and flow rate of electrolytes, generation current and carrier gas flow rate) were optimized for each newly constructed electrolytic cell. Under the optimal working parameters, the basic characteristics of selenium determination were found out by using electrochemical hydride generation. The electrolytic cells were compared to each other and with the classical electrolytic cell...
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Novák, Petr. "Nový atomizátor pro AAS na principu plazmového výboje typu dielectric barrier discharge." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-342902.
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Atomization of arsine in a novel hydride atomizer for atomic absorption spectrometry (HG-AAS) was thoroughly optimized. This plasma atomizer is based on a dielectric barrier discharge (DBD). Sensitivity and detection limit reached 0.48 s ng-1 As and 0.16 ng ml-1 As, respectively, under optimum atomization conditions (Ar discharge using a flow rate of 60 ml min-1 Ar, DBD power 17 W). Analytical figures of merit reached in DBD are comparable to those found in an externally heated quartz tube multiatomizer (MMQTA) that was chosen as a model of conventional approach to hydride atomization in HG-AAS. An extent of interferences (Se, Sb, Bi) during As determination was investigated comparing both MMQTA and DBD atomizers. The later one was found to be more resistant towards interferences. A simple preconcentration of As in a DBD atomizer was reached after oxygen introduction into the Ar plasma in the DBD resulting in analyte retention in the atomizer followed by its volatilization once the oxygen flow is switched off. Preconcentration efficiency of 100 % was reached and detection limit improvement by a factor of ten was achieved (0.01 ng ml-1 As, preconcentration period 300 s).
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Zurynková, Pavla. "HG-AAS s atomizací v plazmovém výboji s dielektrickou bariérou: optimalizace metody a analytické aplikace." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-352468.
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The aim of this diploma thesis was to optimize in detail atomization conditions for antimony hydride in a novel plasma atomizer based on a dielectric barrier discharge (DBD) with atomic absorption spetrometric detection. Argon was found as the best DBD discharge gas employing a flow rate of 50 ml min-1 Ar while the DBD power was optimized at 30 W. Analytical figures of merit including interference study of As, Se and Bi have been subsequently investigated and the results compared to those found in an externally heated quartz tube atomizer (QTA). The limit of detection reached in DBD (0.15 ng ml-1 Sb) is comparable to that observed in QTA (0.14 ng ml-1 Sb). Finally, possibility of stibane preconcentration in a DBD atomizer was studied. Preconcentration efficiency of 102 ± 6 % was found under optimized conditions.
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Petreňová, Štěpánka. "Speciační analýza arzénu s využitím hydridového generování - kryogenního záchytu - plynové chromatografie - atomové absorpční spektrometrie." Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-380273.
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EN The thesis is focused on a speciation analysis of arsenic with use of the hydride generation - cryotrapping - gas chromatography - atomic absorption spectrometry. The aim of this project was the development of a method and instrumentation of the speciation analysis of arsenic based on combination of selective generation of substituted hydrides with a detection by atomic absorption spectrometry and with use of the cryotrapping of generated arsenic species and their separation by the gas chromatography. In the first part of this work the effects of individual parameters which influence the separation in the gas chromatograph were studied. Especially, time of injection from the cryotrap into GC, temperature program, carrier gas flow and carrier gas flow through a "deanswitch". Optimization of these parameters is an attempt to achieve a satisfactory resolution of the individual peaks of arsenic species separated by gas chromatography. Furthermore, an adequate sensitivity of this method is required to be achieved in comparison to other methods that use AAS detection such as a combination of hydride generation with cryotrapping. For this reason, the detection limits and the quantification of arsenic species were important to be determined as well. A sampling coil was replaced by a sampling tip...
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Švadlenová, Veronika. "Stanovení arsenu v pivu a surovinách pro jeho výrobu." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-365110.
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This thesis describes the optimization of the method for determination of arsenic by the chemical hydride generation coupled with AAS detection in beer samples and raw materials for its preparation. The beer usually contain arsenic at ultratrace level, however, it is necessary to monitor the concentration of this element in the beer. The routinely used method for determination of arsenic is determination by electrothermal atomization. This approach is time consuming, expensive and less sensitive. It has been developer suitable determination of arsenic as a faster and less expensive method. For this method there was optimized the flow rate of argon to 75 ml·min-1, the optimum flow rate for the reagents was 4.0 ml·min-1 and for the sample 5.0 ml·min-1 . 3 % NaBH4 in 0.5 % NaOH was used as the reducing agent for the determination of arsenic, and HCl diluted 1:1 with distilled water was used to acidify the sample. With this parameter LOD was 0.32 μg·l-1 and LOQ 1.05 μg·l-1 . It has been tested the arsenic determination in samples of barley, malt and potable water as beer raw materials. It has been found that the beer matrix is unsuitable for the hydride generation technique due to a stormy reaction in the gas/liquid phase separator. The effect of pretreatment, which is likely to enhance the effect of...
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Musil, Stanislav. "On-line předredukce pětimocných sloučenin arsenu kyselinou thioglykolovou pro speciační analýzu atomovou absorpční spektrometrií se selektivním generováním hydridů a kolekcí vymrazováním." Master's thesis, 2007. http://www.nusl.cz/ntk/nusl-373651.
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