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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Srovnání plodů některých odrůd zimolezů z hlediska obsahu vybraných biologicky aktivních látek / Comparison of the fruits of some honeysuckle varieties in terms of content selected biologically active compounds

Veselý, Ondřej January 2015 (has links)
This thesis is focused to the analysis of selected varieties of honeysuckle kamtschatica (Lonicera caerula var kamtschatica) and their comparison in terms of the content of biologically active substances. There were analysed only varieties grown in 2014. Theoretical part elaborates and characterized various parameters of biologically active compounds such as phenolic, anthocyanins and ascorbic acid and possibilities of their determination. Further it briefly surveys Kamchatka honeysuckle, its taxonomic and morphological properties and its nutritional properties. The experimental part of the work was focused on the description of the methods used for the analysis of biologically active substances and their analysis. Polyphenolic compounds and anthocyanin’s were determined spectrophotometrically and vitamin C was determined by high-performance liquid chromatography. The results and varieties were compared with each other. Overall, we can say that the variety with the highest content of all three analysed biologically active substances is a variety Valchová, which had the second highest content of polyphenolic compounds (546.3 mg · 100 g-1 fruits), the third highest contend of ascorbic acid (35.1 mg · 100 g-1 fruits) and the sixth highest content of anthocyanin (170.8 mg · 100 g-1 fruits)
92

Využití separačních metod pro studium vybraných léčiv a pesticidů ve vodách / The Use of Separation Methods for the Study of Selected Drugs and Pesticides in Water

Burešová, Jitka January 2015 (has links)
This work is focused on the study of penetration of pesticides and pharmaceuticals in the aquatic environment. The aim was to develop and verify the optimal method for long-term monitoring of the occurrence of selected pesticides and pharmaceuticals in surface waters. Two frequently used analgesics ibuprofen and diclofenac, and carbamazepine that is used to treat epilepsy, were chosen from the group of drugs. A group of 41 pesticides were selected for monitoring too. The attention was focused on a group of urea pesticides and phenoxyacetic acids, as well as on selected pesticides falling to the group of priority substances or identified as environmental quality standards. Some of pesticides were selected because their consumption in the Czech Republic exceeds 30 tons a year. Liquid chromatography with tandem mass spectrometry (LC / MS / MS) was used for the determination of selected analytes in surface waters. Two optimized analytical method were developed. Ten analytes were determined in negative ion mode and 34 analytes in positive ion mode. Solid phase extraction (SPE) was used for purification and concentration of the samples. Developed methodology was validated and used for monitoring of selected compounds in samples of surface waters from the Morava River basin. Samples were collected on the rivers Morava and Svratka monthly for two years. Samples from the river Blata and stream Nivnička were collected for one year. Surface water samples were also collected from the river Litava. Four samples were taken throughout the length of the flow during one day. Smaller streams were chosen for monitoring because of the probability of occurrence of pesticides. They flow abundantly agriculturally cultivated areas. Drugs ibuprofen and diclofenac were detected in all taken samples, carbamazepine mostly. Among the most commonly occurring pesticides were bentazon, diuron, isoproturon, carbendazim, MCPA, MCPP, propiconazole, tebuconazole and 2,4-D.
93

Přenositelné a miniaturizované separační techniky využitelné pro potravinářské a biotechnologické analýzy / Portable and Miniaturized Separation Techniques Applicable for Food and Biotechnology Analysis

Dvořák, Miloš January 2016 (has links)
Capillary electrophoresis was used for determination of 6 fractions of caseins. Those fractions were measured in 144 samples of cow’s milk originated from the feeding experiment focused on explanation the influence of the feeding onto casein productions. In this work were separated 6 fraction of caseins first time with total resolution of the peaks. Capillary electrophoresis was applied for determination of short-chain organic acids during fermentation of wine must. It was compared the fermentation of must fermented by different yeast. The difference of profile short-chain organic acids during fermentation were not statistically significant. The once difference was in the utilisation of the malic acid and production of the lactic acid. A portable miniaturized system for medium pressure liquid chromatography was developed. The components were tested and system was used for the isocratic and gradient elution of various analytes (food dyes, parabens). New line of electroluminescent diodes (LEDs) for deep-UV areas of wavelength based on a different materials substrate was characterised. The new line was compared with old line LEDs. The new line LEDs was incorporated in deep-UV absorbance detectors. Detectors were characterised and tested for a detection various analytes in modes flow injection analysis and chromatography separation. First time was characterised this new line of the LEDs and the origin of the parasitic emission band produced by deep-UV LEDs light sources was explained. This origin is given by disturbances of a materials substrates. This work is a contribution for an advance of low-cost and portable systems and detection devices in the field of analytical chemistry.
94

Speciační analýza vybraných sloučenin rtuti pomocí HPLC, UV-fotochemického generování studené páry rtuti a její detekce AAS / Speciation Analysis of Selected Mercury Compounds Using HPLC, UV-Photochemical Cold Mercury Vapor Generation and its AAS Detection

Linhart, Ondřej January 2013 (has links)
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...
95

Komplexní analýza výstražných a obranných látek ploštic vysokoúčinnými separačními metodami / Comprehensive analysis of warning and defense compounds of true bugs by high-performance separation methods

Krajíček, Jan January 2016 (has links)
Insects have developed many strategies of defence against predators in the course of evolution. The evolutionarily oldest and most widely used type of defence is chemical defence, followed by acoustic or optical defence. However, many species of insects use simultaneously multiple types of warning signals, which affect different sensory receptors of the given predator. Such a complex method of warning signals is called multimodal method. It may consist of a combination of simultaneous chemical and optical signals, or a combination of acoustic and optical signalling. The combination of chemical and optical signalling used against a predator is probably the most common form of multimodal signalling. The presented work deals with the analysis of biologically active substances, which participate in the defence mechanisms of a widespread species of insects - true bugs (Heteroptera). Pterin derivatives represent a large group of natural compounds derived from pteridin, bicyclic heterocycle, and they are found in virtually all living organisms from bacteria to vertebrates. In insects, they primarily serve as pigments, resulting for example in striking coloration of cuticles of Heteroptera. The first part of the dissertation was focused on identification and quantification of pterin derivatives in cuticles...
96

Využití kapalinové chromatografie ve farmaceutické analýze a příprava monolitických stacionárních fází pro tenkovrstvou chromatografii / Use of liquid chromatography in pharmaceutical analysis and preparation of monolithic stationary phases for thin-layer chromatography

Vojta, Jiří January 2015 (has links)
(EN) In the first part of this work, analytical methods for determination of impurities of active pharmaceutical ingredients (API) in combined pharmaceutical dosage forms were developed and validated. Development of the methods covered both the optimization of sample preparation procedure and chromatographic conditions. The methods were validated according to International Conference on Harmonization guideline and both of them were confirmed to be able to analyze stability samples. Impurities in paracetamol, codeine phosphate hemihydrate and pitophenone hydrochloride in the presence of fourth API fenpiverinium bromide were separated by using ion-pair reversed phase chromatography with gradient elution. Symmetry C18, 250 x 4,6 mm, 5 µm heated to 35 řC was used as a separation column. A diode array detector was used. The detection wavelengths were set as follows: 220 nm for paracetamol impurity K, 245 nm for paracetamol and its other impurities and 285 nm for codeine, pitophenone and their impurities. Impurities in valsartan, amlodipine besylate and hydrochlorothiazide were separated by reversed phase UHPLC method with gradient elution. Chromatographic column Zorbax Eclipse C8 RRHD, 100 x 3,0 mm, 1,8 µm heated to 30 řC and spectrophotometric detection were used. The detection wavelengths were set as...
97

Využití vysokoúčinných separačních metod pro analýzy biologicky aktivních látek / Analysis of biologically active compounds using high performance separation methods

Adamusová, Hana January 2017 (has links)
In the first part of this doctoral thesis, a new analytical HPLC-MS/MS method for monitoring of concentration changes of 17β-estradiol (βE2) during in vitro mouse sperm capacitation was developed. Capacitation was performed for three initial concentrations of βE2 (200, 20 and 2 μg/L). For all the concentrations a similar trend for the total unbound βE2 was observed. In general, the βE2 concentration decreased to reach its minimum and then increased again. The position of the minimum differed for the individual tested βE2 concentrations. Experimentally obtained results were subjected to the kinetic analysis. The curves fitted through the experimentally determined points displayed an autocatalytic character. For the agreement between the curves obtained by fitting through the experimental points and the theoretical calculated curves, it is necessary to assume that the first step is adsorption of βE2 onto the surface of the sperm controlled by Langmuir isotherm. The kinetic study was also used to study the effects of fluorides and aluminium fluoride complexes on the capacitation of mouse sperm. The experimental points were in very good agreement with the shape of the theoretical curves and this fact verifies the mechanism of the mouse sperm capacitation kinetics. In the second part of this work, two...
98

Charakterizace chirálních a achirálních chromatografických separačních systémů / Chromatograhic characterization of chiral and achiral separation systems

Kučerová, Gabriela January 2018 (has links)
Dissertation thesis is a 5-publications' collection concerning characterization and application potential of cyclodextrins, polysaccharides and macrocyclic antibiotics based chiral stationary phases. The effects of stationary phase and mobile phase are studied. This approach ensures the complex insight into separation systems studied. Systems with different nature of chiral selector were studied by HPLC. Namely, macrocyclic antibiotics and derivatized polysaccharides were used for experiments. Former ones provided better results for enantioseparation of non-coded amino acids than latter ones. Dynamic coating procedure was used for preparation of a new chiral stationary phase. Characterization of new cationic cyclodextrin based chiral stationary phase was performed. Linear free energy relationship method was used for characterization of two different separation systems, i.e. newly prepared stationary phase and commercially available stationary phase. Based on results obtained, newly prepared stationary phase showed better results for separation of different achiral groups of analysts. New stationary phase prepared by dynamic coating was compared with chromatographic system, in which the chiral selector was used as a mobile phase additive. The chiral selector used for the two different approaches was...
99

Využití hmotnostní spektrometrie pro analýzu biologicky aktivních látek / Utilization of mass spectrometry for analysis of biologically active compounds

Kaliba, David January 2018 (has links)
This PhD thesis provides a commented set of four publications. These publications are focused on capillary electrophoresis, liquid chromatography, and UV/Vis spectrometry used to study complexes of rhenium with aromatic ligands. The methods of mass spectrometry with soft ionization techniques, 1 H and 13 C nuclear magnetic resonance, and infrared spectrometry were used for structural characterization of the individual complexes. The complexes were synthetized in reactions of the rhenium precursor tetrabutylammonium tetrachlorooxorhenate with the corresponding ligand under both aerobic and anaerobic conditions. In the course of the research, it was revealed that the prepared complexes (with Re in the oxidation number +V and +VI) are unstable and their oxidation numbers change to another more stable form (Re+VII ). Sub-projects which were successfully implemented during the research were as follows:  Design and successful realization of the process of synthesis of selected rhenium complexes with aromatic ligands 1,2-dihydroxybenzene, 1,2,3-trihydroxybenzene, and 2,3-dihydroxynaphthalene in reactions with and without air access, and their structural characterization by ESI-MS, APPI- MS, LDI-MS, ESI-MS/MS, NMR, and IR.  ESI-MS SRM and UV/Vis time studies of the behaviour of primary rhenium complexes...
100

Stanovení léčiv pomocí HPLC s různými typy detektorů / Determination of drugs by HPLC with different detectors

Benešová, Markéta January 2011 (has links)
This diploma thesis deals with the determination of macrolide antibiotics in wastewater, especially with erythromycin, clarithromycin and roxithromycin. In this time are these pharmaceuticals prescribed quite frequently. Solid phase extraction (SPE) was used for the isolation and the purification of selected analytes from an aqueous matrix; as the suitable procedure was found the using Oasis HLB cartridges. High performance liquid chromatography with mass spectrometry detection (HPLC-MS) was optimized for its analysis of selected pharmaceuticals. The optimized method was used for the determination of pharmaceuticals in real water samples, which was taken at the inflow and the outflow of the urban wastewater treatment plant in Brno-Modřice.

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