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Preconcentration of hydride forming elements in quartz trap in connection with ICP-MS
Kašpar, Miroslav ; Matoušek, Tomáš (advisor) ; Rychlovský, Petr (referee)
Charles Uviversity in Prague Faculty of Science Department of Analytical Chemistry Student: Miroslav Kašpar Supervisor: RNDr. Tomáš Matoušek, Ph.D. Name of Thesis: Preconcentration of hydride forming elements in quartz trap with ICP-MS detection The aim of this thesis are pilot experiments employing quartz trap (QT) for preconcentration of hydride forming elements and their subsequent detection by inductively coupled plasma mass spectrometry (HG-QT-ICP-MS). Arsenic and antimony were chosen as model analytes. Preconcentration efficiency on quartz surface was studied in a trap, which was integrated into an interface between spray chamber and plasma torch. We have identified a critical loss of analyte during transportation, instability of the plasma due to sudden change of gas composition, poor repeatability and very quick release of Sb from the trap resulting in difficult quantification of Sb signal. Despite the efforts to resolve these experimental problems, so far we were unable to achieve improvements in analytical parameters compared to standard analytical methods. Keywords: Preconcentration, quartz trap, mass spectrometry with inductively coupled plasma, hydride generation, arsenic, antimony
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Trace speciation analysis of arsenic in beverages
Fajgarová, Aneta ; Matoušek, Tomáš (advisor) ; Spěváčková, Věra (referee)
The aim of this bachelor thesis was to determine the toxicologically important arsenic species in beverages (beer, wine and apple juice) with minimal sample preparation. Determination of arsenic species was performed by selective hydride generation of arsenic hydrides with cryogenic collection under liquid nitrogen and detection by atomic absorption spectrometry. In all the samples only inorganic arsenic was found, methyl substituted species were below the limit of detection. The method is suitable for speciation analysis of arsenic in beverages. Detection limits are low enough, the determination is not influenced by the sample matrix. The results were also in good agreement with the determination of total arsenic after mineralization by ICP-MS. Since there is no specified maximum arsenic content in beverages, measured concentrations were compared with the limit for drinking water (10 μg l−1 ). All samples were under this limit, except for one sample of apple juice, which arsenic content was about twice higher. Key words speciation analysis, atomic absorption spektrometry, hydride generation, arsenic, beverages
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Development of post-column hydride generation for analysis of glutathione complexes of arsenic by HPLC-(HG)-ICP-MS
Bradyová, Michaela ; Matoušek, Tomáš (advisor) ; Červený, Václav (referee)
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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Speciation analysis of arsenic-glutathione complexes by ion-pairing HPLC-ICP-MS
Zušťáková, Veronika ; Matoušek, Tomáš (advisor) ; Červený, Václav (referee)
The thesis has focused on the separation of arsenic-glutathione species using ion-pairing high performance liquid chromatography with detection by inductively coupled plasma mass spectrometry. Species were separated on chromatographic column Prodigy ODS (3) using an aqueous mobile phase containing 4.7mM tetrabutylammonium hydroxide (TBAH), 2mM malonic acid and 4% methanol at pH 5.85 in the isocratic mode. Simple arsenic species - arsenite (iAsIII), arsenate (iAsV) monomethylarsenic acid (MAsIII), monomethylarsenous acid (MAsV), dimethylarsenic acid (DMAsIII) and dimethylarsenous acid (DMAsV), which served as arsenic standards to determine retention times, were successfully separated under these conditions. Arsenic-glutathione complexes As(GS)3, MAs(GS)2 and DMAs (GS) were not successfully separated. These complexes provided peaks of simple arsenic species. Peak broadening was observed in the first analysis of As(GS)3 and MAs(GS)2 complexes, which disappeared in subsequent analyses. This broadening probably represents a residual of glutathion complex which disintegrated to single species. Powered by TCPDF (www.tcpdf.org)
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Separation of toxicologically relevant arsenic species for speciation analysis by RP-HPLC-ICP-MS
Kanásová, Mária ; Matoušek, Tomáš (advisor) ; Červený, Václav (referee)
The thesis is mapping possibilities of separation of toxicologically relevant arsenic species complexed with peptides by reversed-phase high-performance liquid chromatography-inductively coupled plasma mass spectrometry (RP-HPLC-ICP-MS). The C18 chromatography column and gradient elution of the mobile phase (0,1% formic acid with gradient of acetonitrile) was used. At these conditions the separation of simple arsenic species - arsenite (As(III)), arsenate (As(V)), monomethylarsenic acid (MA(III)), monomethylarsenous acid (MA(V)), dimethylarsenic acid (DMA(III)) and dimethylarsenous acid (DMA(V)) was not successful. However, separation of arsenic- -glutathione complexes - arsenic triglutathione (ATG), methylarsenic diglutathione (MADG) and dimethylarsenic glutathione (DMAG) was obtained. Several chromatographic peaks were observed at higher concentration of acetonitrile in mobile phase. The analysis of two in vitro methylation mixtures was also examined. Mixtures contained arsenite (As(III)), S-(5'-adenosyl)methionine chloride (SAM), tris(2-carboxyethyl)phosphine (TCEP) and arsenic(3+)methyltrasferase enzyme (AS3MT) probably participating in human arsenic metabolism. Second mixture also included glutathione (GSH). Several chromatographic peaks of complex species were obtained by analyzing these...
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Free Analyte Atom Distribution, Reactions and Analyte Reatomization in Quartz Tube Hydride Atomizers for Atomic Absorption Spectrometry
Matoušek, Tomáš
Free Analyte Atom Distribution, Reactions and Analyte Reatomization in Quartz Tube Hydride Atomizers for Atomic Absorption Spectrometry Abstract of Dissertation Tomáš Matoušek The Dissertation presents summary of studies of processes taking place in quartz tube hydride atomizers for atomic absorption spectrometry. Spatially resolved measurements of free atoms of hydride forming elements within the quartz tube atomizers (QTA) have been introduced. Both the cross-sectional [1] and the longitudinal [2,3] free atom distribution has been thoroughly investigated, bringing valuable information concerning the nature of the processes taking place within QTA. From the practical point of view, no effects arising from an inhomogeneous free atom distribution are to be expected in the most common externally heated atomizer. The role of the tube surface in the decay of the free analyte atoms has been demonstrated. Strong evidence has been obtained on analyte reactions within the QTA, leading to the formation of polyatomic analyte particles enhancing the free atom decay. These reactions are responsible for calibration graph curvature or even roll-over. It should be noted that the existence of such particles was not directly proven here, e.g., by using non-specific absorption or light scattering. On the other hand,...
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Speciation analysis of toxicologocally important forms of arsenic: development and comparison of hydride generation based methods with ICP-MS detection
Trojánková, Nikola ; Matoušek, Tomáš (advisor) ; Száková, Jiřina (referee)
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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Financial analysis of the selected company
Matoušek, Tomáš ; Homolka, Jaroslav (advisor) ; Michal, Michal (referee)
The main goal of this bachelor thesis is to evaluate company named BOHEMILK, a.s. The evaluation will be carried out by financial analysis, focusing on years 2011 to 2014. First part of the thesis is dedicated to theoretical basics of the financial analysis. Description of calculations methods of individual indicators is also written in this part.
The second part is devoted to perform the financial analysis itself based on the knowledges from the first theoretical part. The bachelor thesis also includes chapters dedicated to the characteristic of the company, calculation of the individual method of the financial analysis complemented by description of the result. Next chapter is focused on comparison with other competitors, whose core business is also production of raw milk. Evaluation of the results and suggestion of improvements is written in the last concluding chapter.
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Development of traffic offenses
Matoušek, Tomáš ; Hřebík, František (advisor) ; Šrédl, Karel (referee)
Driving offences are an actual topic, because there are more and more vehicles on the roads of all the time higher power and all the time more "perfect", while personality of the driver remains the same and the consequences of these driving offences are all the time more fatal. However it is strange that adhering to the traffic rules from the side of drivers is very limited and the whole society subconsciously sees resolution of these offences so that the driver obtains a fine on the spot or the offence is reported to the respective administrative body for further hearing. The reality though is much more complicated, as resolving of traffic offences is dealt with in the Act on offences, Traffic act as well as in the Administrative procedure code. Further facts have to be for instance deducted from the Criminal code. The legislators make every effort to adapt traffic regulations not only to the currently growing occurrence of road rage, but also to set more accented rules, which would be not only respected, but also adhered to, by drivers. Probably the greatest progress in the area of driving offences brought the introduction of so called point system, which has not only repressive but also informative and preventive effect. The essence of this system lies in the fact that the most serious offences and criminal offences are rated by points and when committing these the points add up in the register of the driver up to an exactly defined level, beyond which the driving licence is taken away from the driver. Further breakthrough represents the amendment of the Act No. 361/2000Sb., which, among others, incorporates into its content a part of administrative transgressions such as § 125c - offences, which means that the Misdemeanours act should contain only the general part on offences and a procedure provision regarding offence proceedings.
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Analysis of the crude oil price trend
Matoušek, Tomáš ; Čechura, Lukáš (advisor) ; Romana, Romana (referee)
This bachelor thesis is focused on analysis of the price trend on crude oil WTI and crude oil Brent in last 30 years. This thesis aims to clarify important price changes of crude oil and to find out the main circumstances, which caused them, eventually how the factors affected the changes both in positive or negative way. Then determine the price prediction of both crude oil markets. Necessary information are tested by analysis tools used on time series, which are used to evaluate the price development of crude oil and the factors that affect the price trend. Thesis is divided into two main chapters. The first one is devoted to theoretical investigation. The second is practical, which is divided into three subchapters. Theoretical part summarizes main factors affecting the price development of crude oil such are war conflicts, natural influences and others. The first subchapter of practical part mutually compares the price trend of crude oil Brent and WTI. In following subchapter are individually researched significant events that caused the changes of crude oil price in already mentioned period. Last subchapter pays attention on prediction of price trend on both markets. The resulting survey shows up significant mutual dependence between both markets.
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