National Repository of Grey Literature 106 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
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.
Speciation Analysis of Selected Mercury Compounds Using HPLC, UV-Photochemical Cold Mercury Vapor Generation and its AAS Detection
Linhart, Ondřej ; Červený, Václav (advisor) ; Spěváčková, Věra (referee)
The mercury occurs in the environment in a variety of forms. Mercury compounds can be found in the soil, atmosphere, water and living organisms. Although some of the mercury substances are very toxic, they are often used in various sectors of industry, agriculture and medicine. Mercury compounds differ in their toxicity, so it is necessary to do speciation analysis. The aim of this diploma thesis was to develop and validate a new analytical method for the determination of mercury compounds in different samples. This method involves the combination of high performance liquid chromatography, UV-photochemical cold vapor mercury generation and atomic absorption spectrometry. Effective separation of mercury(II), methylmercury(I), ethylmercury(I) and phenylmercury(I) ions and subsequent comparable efficient of mercury cold vapor generation from all of forms was achieved using these techniques. The reached detection limits were 8 µg l-1 , 31 µg l-1 , 16 µg l-1 and 38 µg l-1 . At the end of experimental work, the proposed method of RP-HPLC-UV-CVG- QTAAS was used for the determination of mercury compounds in real samples (fish tissue and water samples: Labe, Vltava and tap water) and in certified reference materials (DORM-3 and DOLT-4). Several methods for extraction of mercury species from solid samples...
The comparison of methods for determination of ascorbic acid in medical formulations
Kohoutová, Petra ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
The aim of this thesis is to compare and assess chosen analytical methods for ascorbic acid determination in pharmaceuticals with respect to their correctness, accuracy, time and finance exigencies. Four methods were chosen alkalimetric titration with visual and instrumental indication, iodometry and spectrophotometry. Pills, capsules and injection solution were chosen as samples of pharmaceuticals. The obtained results as to accuracy of the declared value (or range permitted under Pharmacopoeia) agreed by all titration methods, spectrophotometric determination showed overestimated results. All used methods were approximately equally accurate. As time seems to be most optimal acidobasic titration with visual indication, while demanding in terms of time was spectrophotometry. If we consider methods on financial intensity all titration methods were quite equal.

National Repository of Grey Literature : 106 records found   previous11 - 20nextend  jump to record:
See also: similar author names
2 Červený, Vojtěch
Interested in being notified about new results for this query?
Subscribe to the RSS feed.