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Determination of diquat and paraquat in agricultural commodities
Prchal, Miroslav ; Hrbek,, Vojtěch (referee) ; Petra,, Kosubová (advisor)
This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.
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Determination of diquat and paraquat in agricultural commodities
Prchal, Miroslav ; Hrbek,, Vojtěch (referee) ; Petra,, Kosubová (advisor)
This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.
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Effect of oxidative stress on telomere lenght in \kur{Drosophila melanogaster}
SZAKOSOVÁ, Klára
Oxidative stress is caused by an imbalance between high production of reactive oxygen species and ability of organism to detoxify them or counteract their effects. The chromosomal ends telomeres - are specialized nucleoprotein structures protecting chromosome ends from DNA damage. Telomeres of Drosophila melanogaster are arrays of specific non-long terminal repeated (LTR) retrotransposons HeT-A, TART and TAHRE. This thesis evaluates effects of exposure of paraquat, which is a strong oxidative stress inducer, on telomere length and transcription activity in Drosophila.
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Effect of oxidative stress on antioxidant systems, telomere length and telomerase activity in \kur{Locusta migratoria}
VRBOVÁ, Kristýna
Oxidative stress is caused by an imbalance between oxidants and antioxidants. Oxidative stress generated by reactive oxygen species (ROS) or reactive nitrogen species (RNS) occurs when protection of antioxidants fails or when an amount of ROS is too high. Telomeres, regions of repetitive nucleotide sequences at the end of chromosomes, are especially sensitive to oxidative stress because they contain a lot of guanine which is often oxidised. Antioxidants play an important role in protection against oxidative stress. In this thesis I analysed the effect of oxidative stress caused by paraquat on activity of antioxidant enzymes (catalase and superoxide dismutase) and telomere length in Locusta migratoria. I also studied differences in telomere length between locusts of various development stages and telomerase activity in locusts and other Orthoptera.
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Effect of oxidative stress on antioxidant enzymes in \kur{Drosophila melanogaster}.
SZAKOSOVÁ, Klára
Oxidative stress reflects an imbalance between reactive oxygen species and antioxidant defense, which can result in cellular damage. The reactive radicals can interact with cell components, including proteins, lipids and nucleic acid. Antioxidant enzymes are the main defense against oxidative stress, representing by two the most important enzymes, catalase and superoxide dismutase. In this thesis I studied the effect of oxidative stress on activity of antioxidant enzymes in Drosophila melanogaster and Locusta migratoria, after exposure to the herbicide paraquat.
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