Today, the information about total mercury content in a sample is not enough to know because of different toxicity of various species like inorganic forms such as Hg+ , Hg+II and organic bonded mercury in Methyl-mercury, Ethyl-mercury or Phenyl-mercury. Therefore a speciation analysis is needed to do. The aim of this diploma thesis was to develop and validate a new method for speciation determination of selected mercury compounds. This method comprises a connection of high performance liquid chromatography, electrochemical mercury cold vapor generation as a postcolumn derivatization technique and atomic absorption spectrometer. Using this on-line connection of mentioned techniques, an efficient separation of Hg+II and methylmercury was achieved. Reached limits of detection were 0.3 µgml-1 and 0.5 µgml-1 for Hg+II and methylmercury, respectively. At the end of experimental work, proposed hyphenated technique HPLC- EcMCVG-QFAAS was used for determination of these two mercury compounds in six real tap water samples (Bílý potok, Bílina, Labe, Vltava, Botič, pond Kovošrot). In Bílý potok, inorganic mercury (Hg+II ) was identified on the base of identical of retention time compared to standard. Standard addition method was used in both FIA and HPLC arrangements and determined content of Hg+II was (0.4...

This thesis deals with optimization of conditions of photochemical generation of volatile species of nickel for atomic absorption spectrometry. The volatile species of nickel were generated in the flow arrangement, when sample was injected to a stream of a reaction medium. Either formic acid was used as the reaction medium or formic acid with the addition of formate anions. Two types of a generator were tested, a generator with a PTFE tube wrapped around a mercury UV lamp and a high efficiency generator with an inside channel. At the same time, two types of a gas-liquid separator were tested. Diffusion flame was used as an atomizer due to its high robustness. Quartz atomizer didn't provide higher sensitivity and measurements had worse repeatability. All the parameters affecting atomization in the diffusion flame were optimized (flow rates and composition of gases, observation height). In the next section, conditions of generation (irradiation time, HCOOH concentration, addition of formate anions) were optimized. Interferences of inorganic acids in photochemical generation were investigated as well. It was found out that the generator with the inside channel provided slightly higher sensitivity and thus generation efficiency than the generator with the PTFE tube wrapped around. Transmission of...

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...

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...

This master's thesis deals with the optimization of conditions for photochemical generation of volatile species of cobalt. Volatile species of cobalt were generated in a flow injection system using a high-efficiency flow through UV generator from formic acid based medium. For detection a high-resolution continuum source atomic absorption spectrometer was used. The volatile species were atomized using a diffusion flame atomizer because of its high robustness. First the optimizations of the parameters affecting the atomization in the diffusion flame and the parameters affecting the transport of the volatile species from the UV generator into the atomizer were carried out (flow rates and composition of the gases, type of a separator, observation height). After that, the optimization of the parameters of the photochemical generation itself was carried out. These were the composition of a reaction medium (concentration of formic acid and formate, type of formate salt) and irradiation time. The possibility of generation of the volatile species from acetic acid based medium was also investigated, but no signal was observed. At chosen optimal conditions of generation the influence of potential interferents was examined, mainly from inorganic acids (HNO3 and HCl) and some transition metals (Fe, Cu and Ni)....

Generation and atomization of cadmium volatile compounds was optimized in this work in order to determine trace Cd concentration levels by volatile compound generation (VCG) with subsequent detection by atomic absorption spectrometry (AAS). Three designs of volatile compound generators have been tested including a conventional hydride generator in flow injection analysis (FIA) mode, a batch generator as well as a generator of volatile compounds of transition metals. The generation efficiency of Cd species was quantified as low as 4 % in the conventional hydride generator. Providing that dissolved oxygen was removed from the reaction solutions, the generation efficiency of Cd increased to 12 % in the same experimental arrangement. The highest Cd generation efficiency of 54 % was reached in the generator of volatile compounds of transition metals. In this set up a detection limit of 0.07 ng ml-1 Cd and a sensitivity of 3.2 s ng-1 Cd, respectively, were reached. Moreover, the structure of the volatile Cd species generated was identified as free atoms in all experimental arrangements of the generators investigated. Keywords atomic absorption spectrometry, cadmium, generation of volatile compounds, atomization of volatile compounds

Eyewitness identification plays an important role during criminal proceedings and may lead to prosecution and conviction of a suspect. One of the methods of eyewitness identification is a police photo lineup when a collection of photographs is presented to the witness in order to identify the perpetrator of the crime. In the lineup, there is typically at most one photograph (typically exactly one) of the suspect and the remaining photographs are the so-called fillers, i.e. photographs of innocent people. Positive identification of the suspect by the witness may result in charge or conviction of the suspect. Assembly of the lineup is a challenging and tedious problem, because the wrong selection of the fillers may end up in a biased lineup, where the suspect will stand out from the fillers and would be easily identifiable even by a highly uncertain witness. The reason why it is tedious is due to the fact that this process is still done manually or only semi-automatically. This thesis tries to solve both issues by proposing a model that will be capable of generating synthetic data, together with an application that will allow users to obtain the fillers for a given suspect's photograph. 1

This thesis deals with the study of UV-photochemical generation of volatile compounds (UV-PVG) in connection with atomic absorption spectrometry (AAS). Selenium (Se(IV)) was selected as a model analyte and many experiments were carried out to expand the current sum of knowledge of the topic. The study was commenced by assembling the UV-PVG apparatus in the continuous flow mode. The detection method used was AAS with externally heated quartz furnace atomizer. The focus of the first step of the study was on the construction of the volatile compounds generator (UV-photoreactor) with emphasis on the material used; tubes made of teflon or quartz of different diameters were tested. The construction of the apparatus was followed by optimization of the reaction conditions (the type and concentration of the photochemical agent and other agents, which increase the analytical signal; the carrier gas and the auxiliary hydrogen gas flow rate; the sample flow rate). Eventually, the analytical figures of merit of the selenium determination using the proposed method were found. The results showed that teflon reaction tubes are a good competitor to those made of quartz. The accuracy of the method has been successfully verified by analysis of certified reference material and its applicability has been further tested...

This thesis is focused on increasing the senstitivity of gold determination by electrochemical volatile species generation using two different types of electrolytic cells in continuous flow setting. Externally heated quartz tube atomizer was used as means of atomization and detection of gold with atomic absorption spectrometer. Generation parameters were optimized for electrolytic cell with an ion exchange (nafion) membrane. After selection of new cathode material (Cu) the carrier gas (Ar) flow rate was optimized, where an additional inlet of carrier gas was found to have possitive effect on increasing the sensitivity of determination of gold and efficiency of volatile specie transport to the atomizer. Experiments with Antifoam B showed possitive effect on generation, thus calibration was carried out for optimized experimetal conditions reaching detection limit of 0,53 mg.dm−3 . The efficiency of volatile specie transfer from liquid to gaseous phase was determined between 60 - 65 % by measuring the residual gold content in liquid waste by F-AAS method. Subsequently the effieciency of electrolytic generation of volatile gold specie with radioactive tracer isotopes and autoradigraphy was determined to 0,6 %. These methods confirmed adsorption of generated species on apparatus surface. Using ICP-MS as...

Title: Pattern matching in compilers Author: Ondřej Bílka Department: Department of Applied Mathematics Supervisor: Jan Hubička, Department of Applied Mathematics Abstract: In this thesis we develop tools for effective and flexible pattern matching. We introduce a new pattern matching system called amethyst. Amethyst is not only a generator of parsers of programming languages, but can also serve as an alternative to tools for matching regular expressions. Our framework also produces dynamic parsers. Its intended use is in the context of IDE (accurate syntax highlighting and error detection on the fly). Amethyst offers pattern matching of general data structures. This makes it a useful tool for implement- ing compiler optimizations such as constant folding, instruction scheduling, and dataflow analysis in general. The parsers produced are essentially top-down parsers. Linear time complexity is obtained by introducing the novel notion of structured grammars and reg- ularized regular expressions. Amethyst uses techniques known from compiler optimizations to produce effective parsers. Keywords: Packrat parsing, dynamic parsing, structured grammars, functional programming 1