National Repository of Grey Literature 100 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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...
Porous silicon based optical sensors of chemical species for gas phase
Liška, Jiří ; Dian, Juraj (advisor) ; Červený, Václav (referee)
Title: Porous silicon-based optical sensors of chemical species for gas phase Author: Bc. Jiří Liška Department: Department of Inorganic Chemistry Supervisor: doc. RNDr. Juraj Dian, CSc. Abstract: Porous silicon is a nanostructured material, which is a suitable material for che- mical sensors due to its optical properties, especially photoluminescence and its quenching depending on the chemicals in the environment. Optical sensors based on porous silicon are the most studied group of sensors and have been successfully used for the detection of chemicals in both liquid and gas phases. In addition, the surface of porous silicon can be modified by a number of techniques, thereby modifying the recognition properties. In the case of combining multiple sensor elements of different properties, it is possible to measure multiple responses in the photoluminescent sensor array. The objectives of this thesis are: 1. Extension of electrochemical characterisation of initial silicon substrates using vol- tammetric techniques under different lighting conditions during the experiment, preparation of porous silicon samples from different types of crystalline silicon sub- strates (p-type, n-type), crystallographic orientation and doping degree. 2. Functionalisation of porous silicon surface with new chemical compounds by...
Application of a commercial multimode sample introduction system as a generator of volatile compounds
Hadbavníková, Alexandra ; Nováková, Eliška (advisor) ; Červený, Václav (referee)
EN The main goal of this thesis was the determination of zinc using a commercial multimode sample introduction system (MSIS) as a generator of volatile compounds with inductively coupled plasma mass spectrometer as detector. The generation of volatile compounds took place using sodium borohydride in an acid environment. In the first step of the experiment, the following parameters affecting the generation of volatile compounds were optimized: acid selection, acid concentration, sodium hydroxide concentration, mass concentration of sodium borohydride, mass concentration of 8-hydroxyquinoline, volume of the injection loop and flow rates of sample, carrier gas and hydrogen. Subsequently, figures of merit of the method were determined under optimal conditions. The limit of detection was 2.8 μg·dm-3 and the limit of quantification was 9.3 μg·dm-3 . Generation efficiency of the volatile zinc compound was determined as 3.7 %, which is the highest efficiency yet achieved for this element and generation system in this laboratory. Interference studies did not demonstrate the ability of any of the tested hydride-forming or transition elements to act as a modifier increasing the generation efficiency, but at the same time, none of the investigated elements proved to be a significant interferent. Key words...
Determination of selected elements in coffee samples using ICP-MS method
Švecová, Pavla ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
EN The main aim of this thesis is focused on the determination of selected elements (manganese, copper, zinc, iron) in trace levels in selected samples of grained and instant coffee. Four samples of grained coffee and one sample of instant coffee were taken for analysis. Firstly, all samples were digested in a microwave digestion system and then analysed by inductively coupled plasma mass spectrometry to determine the concentration of selected elements. Except this, one sample of grained coffee was taken for two additional experiments. The aim of these experiments was to investigate the influence of the extraction time and temperature of water used for extractions, on the element concentrations in liquid phases. The content of elements in the analysed samples shows relatively wide range of values (7.58 - 34.4, 0.21 - 13.6, 1.58 - 5.35 and 12.2 - 55.8 µg/g for manganese, copper, zinc and iron, respectively). Generally, the lowest concentrations of all elements were detected in sample of instant coffee, which cannot be regarded as a valuable source of trace elements for humans. The first additional experiment shows that the concentrations of elements in grained coffee is much higher than in its extractions. With increasing time of extraction, the concentration of elements increased as well (except of...
Sequential Injection Analysis for Spectrophotometric and Spectrofluorometric Determination of Chlorpromazine, Levomepromazine and Promethazine
Kroiherová, Anna ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
In this diploma thesis, a method using the sequence analysis technique for spectrometric and spectrofluorimetric analysis of three selected analytes from the group of phenothiazines (chlorpromazine, levomepromazine and promethazine) was developed and optimized. The determination is based on the oxidation reaction of phenothiazines with cerium(IV) ions in an acidic medium, which produces a color product that is detected by VIS spectrometry or spectrofluorimetry. The measurement conditions for sequence analysis were optimized and evaluation was performed by nonlinear calibration in the dynamic range of 3−320 mg dm−3 for VIS spectrometric detection and 0.3−50.0 mg dm−3 for spectrofluorimetric detection. The influence of water-soluble common excipients (fructose, glucose, lactose), which are often part of medicinal products, was investigated. The developed sequential injection analysis with both detections was successfully applied to authentic samples of drugs (Plegomazine, Tisercine and Prothazine) containing the analyzed phenothiazines. The measurement results were in good agreement with the used reference method of direct UV spectrometry. The advantages of developed SIA method with VIS spectrometric and spectrofluorometric detection are its automation, speed, low consumption of reagent and a wide...
The Flow Injection Analysis of Procaine and Sulfamethoxazole with Spectrophotometric Detection
Baptistová, Adéla ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
A derivatization reaction, based on a copulation reaction of diazonium salt of an analyte with a reagent (1-aminonaphthalene or NEDA) producing colour, spectrophotometrically detectable product, has been used for determination of two analytes (procain hydrochloride, sulfamethoxazole) containing amino group in the molecule. The conditions of batch spectrophotometric determination were studied. It was found, that the batch determination is applicable only for procain hydrochloride analysis, because sulfamethoxazole gives time-unstable colour product. FIA arrangement was proposed and effects of selected parameters were optimized using two levels factorial design. The calibration dependences were measured for both analysis with both reagents, and subsequently were applied on determination of analytes in medical forms. Key words: diazotization, flow injection analysis, procaine, spectrophotometry, sulfamethoxazole
Comparision of methods for sulphide determination
Zlámalová, Magda ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
The aim of this work is determination of sulphides in a solution by suitable methods and it's subsequent comparison from a point of view to the precision, financial and time demands. Iodometric titration, argentometric titration, and potassium ferricyanide titration were chosen for the determination of sulphides in the solution. Anhydrous sodium sulphide and sodium sulphide hydrate were used as model samples. From the point of view to financial and time demands the most advantageous method was potassium ferricyanide titration and the least advantageous method was iodometric titration. The precision of used methods was dependent on type of used sample. Iodometry was the least precise determination of sulphides in the sample of anhydrous sodium sulphide; the precision of argentometry and potassium ferricyanide titration was comparable. Potassium ferricyanide titration was the most precise determination of sulphides in the sample of sodium sulfide hydrate; the least precise determination was argentometry.
Possibilities of electrochemical generation of volatile compound of silver
Linhart, Ondřej ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The presented bachelor thesis is to focus on the possibilities of electrochemical generation of volatile form of silver coupled with atomic absorption spectrometry which was used as a detection technique. The main aim was to optimize working parameters. A thin-layer electrolytic cell and a tubular electrolytic cell have been tested for the electrochemical generation of volatile form of silver. The optimization of appropriate electrolyte, its concentration and its flow rate, electric current and flow rate of carrier gas have been developed. Under the optimal working conditions the sensitivity of 0.029 dm mg-1 for the determination of silver by electrochemical generation was achieved.
Determination of As2O3 in homeopathic products Arsenicum Album using atomic absorption spectrometry with hydride generation
Cmuntová, Kateřina ; Červený, Václav (advisor) ; Kratzer, Jan (referee)
This bachelor thesis is intent on As determination in various types of homeopathic remedy Arsenicum Album which are available in Czech Republic. The method selected for this determination is atomic absorption spectrometry with hydride generation. The content of As2O3 in recommended daily dose of homeopathic was confronted with toxicologically referred maximal dose and it was discussed if there is any risk of health damage by using Arsenicum Album.

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1 Červený, Vojtěch
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