|
|
Study of microplastic sorption properties
Hlaváčková, Hana ; Kučerík, Jiří (referee) ; Řezáčová, Veronika (advisor)
There is currently an effort to replace conventional plastics with biodegradable products that will have the ability to replace these substances. One of the possible biodegradable felt, which is currently being studied in detail, is also poly (3-hydroxybutyrate), which is produced by bacteria. This bachelor thesis deals with the sorption of selected substances on poly(3-hydroxybutyrate) microparticles. Substances whose contamination of water sources is a significant problem today have been selected for this work. Specifically, the sorption of the nonsteroidal anti-inflammatory substance ibuprofen, the triazole fungicide tebuconazole and the most common drug caffeine on PHB particles, which fall in the size of the microplastic group, were studied. The method of liquid chromatography with mass detection was used for analyzes.
|
|
|
Analytical approaches to study group interactions of azole pesticides with important biological active compounds
Kovač, Ishak ; Jaklová Dytrtová, Jana (advisor) ; Száková, Jiřina (referee) ; Navrátil, Tomáš (referee)
This dissertation presents a developed capillary electrophoresis method for analysing residues of triazole fungicides (TAF) from real samples ("Sweet cherry" tomato - Solanum lycopersicum L) and shows its potential application in environmental analysis. The developed method was validated in-house and characterised by a relatively short analysis time and low cost with sufficient LOD and LOQ. As an additional part of this dissertation, which rose from the tomato plants' treatment with TAF, we studied the impact of triazole fungicides on plant development and their impact on biologically active compounds. Determination of TAF residues from tomato peel carried out with capillary electrophoresis. Capillary electrophoresis is a versatile technique with minute amounts of sample required, with high efficiency in separating small molecules, such as selected TAF. The developed method, cyclodextrin-modified micellar electrokinetic chromatography, accomplished a baseline separation of the TAF mixture from tomato peel. The optimal conditions for separation were in the background electrolyte comprised of phosphoric acid and Tris (100 mM concentration, respectively), 20% v/v methanol, with apparent p[H+ ] 4.8. The constituents of the mixed micellar pseudo-stationary phase were ionic detergent sodium dodecyl...
|
|
|
Interaction of triazole terconazole with copper cations.
Bártová, Kateřina ; Jaklová Dytrtová, Jana (advisor) ; Navrátil, Tomáš (referee)
Terconazole is one of the triazole derivatives with an antifungal effect. It is used locally to treat vaginal yeast infections. Terconazole could interact with copper cations in the vagina or uterus of women, who use an intrauterine device releasing copper cations. Other triazole derivatives in complexes with copper cations differ in their properties like toxicity or mobility. Cu2+ can be reduced in the presence of triazoles, which can lead to a Fenton-like reaction and production of free radicals. Thus, the Cu2+ /Cu+ terconazole system can be potentially dangerous. Stoichiometry, fragmentation and stability of forming complexes were studied with tandem mass spectrometry. The Cu2+ /Cu+ terconazole system was measured within pH range from 4 to 7,2, with a concentration ratio of CuCl2 and terconazole 1:5 to 20:1, with water and ethanol as solvents (1:1). Results suggest that terconazole is partially oxidized in the Cu2+ /terconazole system and that this oxidation depends on the pH of a solution. Apart from oxidized and protonated terconazole, other detected ions and complexes were not significantly influenced by pH. The detection of complexes containing Cu+ is alarming because this could correspond with the occurrence of a Fenton-like reaction. Key words Terconazole, copper cations, complexes,...
|
|
|
Utilization of complexation of tebuconazole with Cu(II) ions for its voltammetric detection
Dostálková, Lucie ; Fischer, Jan (advisor) ; Křížek, Tomáš (referee)
Tebuconazole is a triazole fungicide used in agriculture that can be present in the environment and have a negative effect on various organisms. Therefore, the electrochemical properties of tebuconazole and its complexation with Cu(II) ions on a boron doped diamond electrode were studied for its possible indirect detection in the presence of these ions. For the determination of Cu(II) ions, conditions in the concentration range 0.1-10 mol l-1 were optimized by differential pulse voltammetry in a 0.01 mol l-1 HNO3 environment on anodically oxidized BDDE, the limit of quantitation was 0.087 µmol l-1 . After optimization of the conditions, the indirect determination of tebuconazole was tested. The signal of free Cu(II) ions after the addition of tebuconazole was monitored. A decrease in this signal was observed and a linear calibration dependence could be measured for a decrease in the signal of 10 µmol l-1 Cu(NO3)2 in the concentration range of 2-10 µmol l-1 tebuconazole and for 1 µmol l-1 Cu(NO3)2 in the concentration range of 2-10 µmol l-1 and 10-100 µmol l-1 tebuconazole. Complexation of tebuconazole with Cu2+ was shown to occur almost instantaneously. Tebuconazole itself gives an anodic peak at a potential of +1550 mV in aqueous medium of 0.01 mol l-1 HNO3. Using differential pulse voltammetry,...
|
|
|
Study of microplastic sorption properties
Hlaváčková, Hana ; Kučerík, Jiří (referee) ; Řezáčová, Veronika (advisor)
There is currently an effort to replace conventional plastics with biodegradable products that will have the ability to replace these substances. One of the possible biodegradable felt, which is currently being studied in detail, is also poly (3-hydroxybutyrate), which is produced by bacteria. This bachelor thesis deals with the sorption of selected substances on poly(3-hydroxybutyrate) microparticles. Substances whose contamination of water sources is a significant problem today have been selected for this work. Specifically, the sorption of the nonsteroidal anti-inflammatory substance ibuprofen, the triazole fungicide tebuconazole and the most common drug caffeine on PHB particles, which fall in the size of the microplastic group, were studied. The method of liquid chromatography with mass detection was used for analyzes.
|
|
|
Separation of triazoles from real samples with capillary electrophoresis
Kovač, Ishak ; Jakl, M. ; Šolínová, Veronika ; Jaklová Dytrtová, Jana
The CE has become one of the advantageous tools in fungicides analysis in complex matrices due to its simplicity and separation efficiency. The separation of a group of thee triazole (i.e. penconazole, tebuconazole, and cyproconazole) fungicides was achieved with CD-MEKC with anionic Sg-CD as a selector at pH=4,8. The background electrolyte consisted of TRIS phosphate buffer (50 mmol/L) and 15 mmol/L SDS. The separation was performed on uncoated fused silica capillary with 500/425 mm (total/effective) length under -15 kV separation voltage. Achieved LOD values with this method were: 0,73, 1,88, 0,60, 1,18 (umol/L) for penconazole, tebuconazole, cyproconazole A and B respectively.
|
|
|
Study of tebuconazole complexes with metal ionts
Norková, Renáta ; Jaklová Dytrtová, Jana (advisor) ; Vyskočil, Vlastimil (referee)
Tebuconazole belongs to widely utilized plant fungicides, mostly in vineyards. Its traces are present in plant tissues, wine as well as in soil. The aim of the study was to determine stoichiometries and stabilities of metal (Cu, Zn, Cd, Ca and Ag) complexes with tebuconazole (1) by means of electrospray ionization mass spectrommetry (ESI-MS). It was found that the complexes of tebuconazole with copper ions are particularly stable ([Cu(1)]+ has appearance energy 224 kJ·mol-1 , corresponding with the dissociation of the water molecule from the tebuconazole molecule), while the stability of another tebuconazole complexes is lower, about 150 kJ·mol-1 . In real environmental samples, the detection of 1 itself is hampered by its spreading into various species. The method involved here is based upon a hyphenation of electrochemistry (amperometry) and electrospray-ionization mass spectrometry (ESI-MS). It uses the fact that Cu creates very stable complexes with 1. We demonstrate that at appropriate potentials (at higher than 500 mV) Cu cations can be generated in an electrochemical cell and subsequently form complexes with 1 present in the sample. The resulting complex [Cu(1)]+ is detected with ESI-MS. The intensity of detected complexes depends on the concentration of 1 and the oxidation level of the...
|
|
|
Use of Copper Solid Amalgam Electrode for Determination of Triazolic Fungicide Tebuvonazole
Nováková, Kateřina ; Navrátil, Tomáš ; Jaklová Dytrtová, Jana ; Chýlková, J.
With the use newly developed mercury meniscus-modified copper solid amalgam electrode (inner diamter 1.5 mm), the voltammetric behavior of fungicide tebuconazole was researched by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Applying CV and elimination voltammetry with linear scan (EVLS), the reaction mechanism was investigated. The optimum conditions for DPV determination of this triazolic fungucude were identified in Britton-Robinson buffer/methanol (1:1, v/v) of pH 6.3 DPV with optimized parameters (Ein = +400 mV vs. Ag/AgCl/3M KCl, scan rate 20 mV s-1) was used for determination of determination of tebuconazole in analyzed solutions. Application the prolonged time (60 s), the limit of detection 2.10-7 molL-1. The applicability of the developed method was verified on the analysis of the real soil solution sample.
|
guest ::
