|
|
Kinetic determination of nitrites with spectrophotometric detection
Vašíčková, Pavla ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
Title: Kinetic determination of nitrites with spectrophotometric detection Annotation: The proposal and optimization of the kinetic determination of nitrites in water samples is the aim of this bachelor thesis. The method is based on the ability of nitrites to catalyze the oxidation of toluidine blue by bromate in acidic media. The course of the reaction is monitored by spectrophotometrically, using a decrease of the absorbance band at 653 nm in the constant period of time from the beginning of the reaction. The dual-chanel manifolds FIA apparatus was proposed and optimized. The calibration dependency in the range of 0,05-1,00 mg ml-1 was measured. The instrumental limit of detection of 0,038 mg ml-1 and limit of quantification of 0,125 mg ml-1 were calculated. The method was applied on real sample of river water. Key words: nitrites, flow-injection analysis, kinetic catalytic methods
|
|
|
Diagnostics of active particles generated by the interaction of plasma microwave discharge with liquids
Kovaříková, Kateřina ; Töröková, Lucie (referee) ; Kozáková, Zdenka (advisor)
The first part of this Bachelor’s thesis describes problems of electric discharges in gas and on a surface of water solutions. It focuses on the generation of the active particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on identification of the active particles that are generated during the microwave discharge in gas phase and during the interaction with water solution surface. The aim is to determine the influence of experimental conditions on the information of the active particles, specifically the nitrates and nitrite ions.
|
|
|
Kinetic determination of nitrites with spectrophotometric detection
Vašíčková, Pavla ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
Title: Kinetic determination of nitrites with spectrophotometric detection Annotation: The proposal and optimization of the kinetic determination of nitrites in water samples is the aim of this bachelor thesis. The method is based on the ability of nitrites to catalyze the oxidation of toluidine blue by bromate in acidic media. The course of the reaction is monitored by spectrophotometrically, using a decrease of the absorbance band at 653 nm in the constant period of time from the beginning of the reaction. The dual-chanel manifolds FIA apparatus was proposed and optimized. The calibration dependency in the range of 0,05-1,00 mg ml-1 was measured. The instrumental limit of detection of 0,038 mg ml-1 and limit of quantification of 0,125 mg ml-1 were calculated. The method was applied on real sample of river water. Key words: nitrites, flow-injection analysis, kinetic catalytic methods
|
|
|
Application of Selected Methods for Oxidative Stress Analysis
Lízalová, Martina ; Tremlová, Bohuslava (referee) ; Beklová, Miroslava (referee) ; Vávrová, Milada (referee) ; Lojek, Antonín (advisor)
Chronic pancreatitis (CP) is a heterogeneous disease defined as chronic inflammatory changes of the pancreatic tissue caused by variety of aetiologies. Oxidative stress accompanying the inflammatory processes has been suggested as an important factor contributing to CP development. The aim of this study was to determine levels of lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), together with nitrites, the total antioxidant capacity, cytokines, biochemical and haematological parameters in the plasma of patients with CP and control subjects. Levels of MDA and 4-HNE were analyzed using high-performance liquid chromatography. The total antioxidant capacity of plasma against peroxyl radicals was evaluated using chemiluminescence determination. Nitrites were determined using Griess reaction. Cytokines - TNF-alfa; TNF RI; PDGF-AB; TGF-beta, together with myeloperoxidase and hyaluronan were determined using ELISA Kits. Biochemical and haematological parameters were measured by standard methods.
|
|
|
Hematological changes in fish exposed to nitrites
FRANĚK, Roman
The aim of the thesis was to determine the effect of nitrite on hematological indices of rainbow trout (Oncorhynchus mykiss) and Nile tilapia (Oreochromis niloticus). After the fish were exposed to various concentrations of nitrites were determined 48hLC50. For the main test only fractional concentrations of these values were used. For rainbow trout it was 8 mg.l-1 NO2?, for Nile tilapia 11 mg.l-1 NO2?. The exposure of both species lasted for 48 hours. From fish blood were made blood smears to determine the influence of nitrite on size changes of erythrocytes and hematological parameters were set also. The effect of nitrite on changes in the ultrastructure of erythrocytes was determined by the electron microscopy. The erythrocyte nuclei of rainbow trout showed significant (p <0.05) shrinkage. The images of the electron microscope showed an increased amount of changes, especially in the form of various units within the cytoplasm of erythrocytes, was also visible nuclei shrinkage. There was significant (p < 0.01) reduction in the amount of hemoglobin and significant (p < 0.01) increase in the concentration of methemoglobin levels of the exposed groups. In the number of erythrocytes and hematocrit were not detected any changes. Hematological parameters of Nile tilapia did not show any size changes in the measured parameters, no changes were detected in the count of erythrocytes, hemoglobin and hematocrit values.
|
|
| |
|
|
Methods of the separation of the base flow and trends of nitrogen concentrations in this base flow
MAIEROVÁ, Monika
This Bachelor thesis is aimed to clarify the hydrological cycle, hydrological balance, groundwater hydrology, the selected basic baseflow separation methods of comparing them and last but not least, nitrogen cycle, nitrogen, nitrates, ammonia nitrogen and nitrogen in groundwater. In the work there is also closely analyzed the total, surface and subsurface outflow and the detailed division. The methods of the groundwater baseflow separation are described with regard to content of nitrogen compounds., which currently create the most common type of pollution of groundwater used as drinking sources.
|
|
|
Chemical hazards of contamination of foodstuffs and dishes
MARŠÁLKOVÁ, Alena
The bachelor thesis deals with the risks of chemical contamination of food and possible health risks for the consumers. Firstly, there is a general outline of foreign substances including the additives, which are added to foods intentionally, and contaminants. The contaminants are viewed as undesirable substances which occasionally occur in foods. They develop directly in the foods or penetrate into them from the outside during the basic stages of agricultural production, in stores, during transportation or during processing for culinary purposes, or due to environmental pollution. Such substances can have negative effects on human health. The second part of the thesis focuses on concrete contaminants - nitrates, nitrites and acrylamide. Nitrates and nitrites are both contaminants and additives. Their use as food additives is motivated by their sensoric and protective effects. The sensoric function is to ensure a permanent pink colour of smoked meat and other meat products. The protective function consists in inhibiting the growth of the microorganisms Clostridium botulinum and thus preventing the origination of dangerous botulin. The nitrates exist as contaminants mainly in foods of vegetable origin, penetrating them from soil and water due to nitrogen cycle in the nature. The acrylamide is a newly discovered food contaminant. It is considered to be a very dangerous substance as regards possible peroral exposure. The danger consists in its neurotoxic, genotoxic and possible carcinogenic effects. It originates in foods with a higher content of reducing sugars during the process of production or culinary processing if the temperature is higher than 120° C. The thesis should provide information for the public as consumers or providers of different food-processing facilities. Its main objective is to pinpoint some risks connected with the consumption of various foods and meals, and to eliminate the risks as much as possible or to avoid them completely.
|
guest ::
