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Characterization of curcumin nanocrystals in capillary electrophoresis
Dvořáková, Amálie ; Křížek, Tomáš (advisor) ; Sobotníková, Jana (referee)
This Bachelor thesis deals with the characterization of curcumin nanocrystals using capillary electrophoresis with UV-VIS and laser-induced fluorescence (LIF) detection. Curcumin is a natural polyphenolic substance with many biological effects. Its low solubility is one of the main reasons for its low bioavailability, however, it can be increased by preparing curcumin nanocrystals. In the experimental part, the effects of the composition of the background electrolyte (BGE) and the applied voltage on the curcumin nanocrystals were investigated. Background electrolytes were prepared using phosphoric acid, or HEPES and their pH was adjusted to 7.0 by NaOH, or TRIS, to test whether the shape of the peak is influenced by the ionic strength of BGE and not by the increasing concentration of a particular BGE component. Initial experiments did not involve voltage application, but only a pressure of 50 mbar. In following experiments both positive and negative voltages were applied, using a 10mM phosphate buffer, the pH of which was adjusted using TRIS. Most of the experiments were conducted using a 100nm curcumin nanocrystals sample. Curcumin nanocrystals provided an abnormally wide peak in both UV-VIS and LIF detection. It was found that the dispersion of the nanocrystal zone was not caused by diffusion,...
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Optimization of dynamic headspace and thermal desorption parameters for introduction of human scent volatile samples into GCxGC-TOFMS
Růžková, Lucie ; Kyjaková, Pavlína (advisor) ; Sobotníková, Jana (referee)
Comprehensive two-dimensional gas chromatography has become one of the most widely used methods for the analysis of human odor, which enables better separation of substances from the sample compared to classical gas chromatography. Dynamic headspace (DHS) with thermal desorption is often used for the transfer of human body odor analytes from the sampling sorbent to the gas chromatograph. The aim of this work was to optimize the parameters of DHS for human body odor samples and two-dimensional gas chromatography. Two parameters of the DHS were chosen for the optimization, namely the volume and flow rate of the inert gas that carries the sample onto the sorbent. A total of 16 settings of these parameters were selected and used to measure samples containing a piece of cotton and a model mixture. The model mixture was prepared to mimic the best the composition of human body odor in terms of polarities and boiling points of the compounds contained in it. The obtained peak areas of the analytes from the model mixture were compared and the most suitable setting of the DHS parameters was found. This setting was tested on a real human odor sample. Keywords: Human odor, GC×GC-TOFMS, dynamic headspace, thermal desorption, model mixture
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Determination of pharmaceuticals in wastewaters
Horkelová, Simona ; Sobotníková, Jana (advisor) ; Coufal, Pavel (referee)
The issue of pharmaceutical accumulation in the environment is a pressing concern today. Annually, the consumption and misuse of pharmaceuticals increase, with a significant portion ultimately being discharged into wastewater. Unfortunately, wastewater treatment processes often prove inadequate in effectively removing these substances, as they were not originally designed for this purpose. Consequently, pharmaceuticals gradually infiltrate water systems, resulting in heightened pollution of surface water, groundwater, and even drinking water sources. Due to insufficient legislation, there is a need for stricter monitoring and elimination of pharmaceutical substances containing. This master's thesis investigates the presence of pharmaceuticals and some metabolites in wastewater samples using an accredited method at ALS Czech Republic laboratory. It compares the input and output concentrations of drugs in wastewater treatment plants of varying sizes and assesses the efficacy of their removal. Additionally, it contrasts municipal sewage treatment plants serving communities with hospital wastewater treatment plants. Key words: LC-MS, pharmaceuticals, metabolites, wastewaters, environment
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Utilization of ultra-high performance liquid chromatography for simultaneous determination of paracetamol, amoxicillin, and doxycycline
Hrašková, Hana ; Kubíčková, Anna (advisor) ; Sobotníková, Jana (referee)
In this study, a method was developed for the simultaneous determination of three pharmaceutical compounds: amoxicillin, doxycycline, and paracetamol. Ultra-high performance liquid chromatography (UHPLC) was employed for the separation. A Kinetex column C18 measuring 100×2,1 mm with a particle size of 1,7 μm was used as the stationary phase. The optimal method was run in gradient mode with a total analysis time of 5 minutes. The mobile phase consisted of a mixture of component A, containing acetonitrile with 0,1% formic acid, and component B, comprising deionized water with 0,1% formic acid. The separation conditions in the column varied according to the following gradient program: 0 - 1,0 min: 10% A (v/v); 1,0 - 1,5 min: 10% → 65% A (v/v); 1,5 - 2,0 min: 65% A (v/v); 2,0 - 2,5 min 65%→10% A (v/v); 2,5 - 5,0 min 10% A (v/v). The pH of the mobile phase was maintained at 2,8. The flow rate was set at 0,3 ml/min, column temperature was maintained at 25řC, and the autosampler temperature was consistently held at 8řC. The injection volume was 1 μl, and analytes were detected using a diode array detector at a wavelength of 245 nm. Drug identification was conducted using a QDA detector set to positive mode with a mass range from 100,00 to 500,00 Da. The method was partially validated by constructing a...
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A study of non-volatile nitroso compounds in brewing
Malečková, Michaela ; Sobotníková, Jana (advisor) ; Čabala, Radomír (referee) ; Karabín, Marcel (referee)
4 Abstract Nitroso compounds are beer contaminants related to carcinogenicity and can be naturally formed during brewing. They are generally categorized as volatile and non-volatile. Well-characterized and proven carcinogenic compounds are mostly volatile N-nitrosamines, whereas specific non-volatile nitroso compounds are nearly unknown even by structure. This deficiency limits improvements in health-risk assessment and control of beer. The present study focused on these barely known compounds in beer, related to their molecule structures and natural occurrence in beer and malt. Since these compounds form by nitrite reactions with naturally occurring compounds in beer or raw materials, the beer sample was parallelly treated by nitrite and isotopically labelled nitrite-15N at acidic conditions. Due to isotopic labelling, formed nitrite-related reaction products were distinguished by gas chromatography with tandem mass spectrometry. By this approach, up to 22 unknown nitrite-related reaction products (N-products) were found and structurally studied from mass spectrometric fragmentation patterns. Besides previously found N-nitrosoproline and N-nitrosoproline ethyl ester, newly characterized compounds in beer were 4-cyanophenol, pyruvic acid oxime, 2-methoxy-5-nitrophenol, nitrosoguaiacol, and 4-nitrosophenol....
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Determination of bisphenols in selected beverages by high-performance liquid chromatography
Marvan, Jiří ; Sobotníková, Jana (advisor) ; Olšovská, Jana (referee)
Bisphenols are chemical compounds with a wide range of uses in the chemical industry. They are used in the production of plastic materials as softeners for polymer materials or epoxy resins, as monomers in the synthesis of polycarbonates, or for the elimination of hydrochloric acid in the production of polyvinyl chloride. This thesis deals with the development, validation, and optimization of an analytical method for the determination of selected bisphenols, specifically bisphenol A, bisphenol B, bisphenol F, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether (BPA, BPB, BPF, BADGE, BFDGE), and their metabolites using the high performance liquid chromatography with mass spectrometry, HPLC/MS, and the application of the method to real samples in selected canned beer samples. The following conditions were optimized for chromatographic separation. The Sigma-Aldrich discovery C18 column (150×2,1 mm, 5µm) was chosen. The mobile phase consisted of a mixture of mobile solvent A, which contained 0,05% ammonium hydroxide, and mobile solvent B, which contained of methanol. The flow rate of the mobile phase was 0,240 ml/min. The total analysis time was 22 minutes, using a 5 μl injection of the sample solution with gradient elution. Next, a partial validation of the method was performed, evaluating...
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The use of high-performance separation techniques for monitoring the bioaccumulation of selected micropollutants in plants of model root treatment plants
Modroczká, Karin ; Sobotníková, Jana (advisor) ; Coufal, Pavel (referee)
This bachelor's thesis deals with the determination of ibuprofen in model root refineries from Phalaris arundinacea extracts. The goal was to find out if the plant is able to accumulate ibuprofen from the aqueous solution which was added to the plant. A HPLC method with UV/VIS detection was also optimized to determine the ibuprofen content. A C18 column (4.6 mm × 150 mm × 3.5 µm) was used to analyse the samples. An isocratic program was used, in which the mobile phase consisted of methanol and an aqueous acetic acid solution of pH = 3,27. As part of the validation of the method, the repeatability, robustness, and yield (which was 99,04 %) of the method were verified. Furthermore, the linearity of the method, which was from 0,01 mg ml-1 to 2,0 mg ml-1 , the limit of detection (LOD = 0,049 mg ml-1 ) and the limit of quantification (LOQ = 0,16 mg ml-1 ) were determined. After the validation of the method, we can claim that the method is accurate, because the values of the relative standard deviations did not exceed 2 %. Infrared spectroscopy was used to verify the purity of ibuprofen batches. Last but not least, it was proven that Phalaris arundinacea has the ability to accumulate ibuprofen from an aqueous solution. Keywords: HPLC, ibuprofen, Phalaris arundinacea, root wastewater treatment plant,...
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The usage of the "Ethanol as internal standard" method for the SPME-GC/FID analysis of volatile compounds in alcoholic products
Zavoralová, Lucie ; Korban, Anton (advisor) ; Sobotníková, Jana (referee)
This bachelor thesis dealt with the optimization of a method for the determination of 10 volatile compounds occurring as minor components in alcoholic products. The quantification was performed by the internal standard method, comparing the results using 1-pentanol and ethanol as classical and proposed internal standards, respectively. In the case of ethanol usage, better repeatability and accuracy of the results were expected as this method does not require any sample pre-treatment. The optimized measurement method was monitored for both internal standards, while following these parameters - repeatability, recovery, linearity and limits of detection and quantification. It was found out that, as expected, the method of the proposed ethanol internal standard gives more accurate results for the analysis of real alcoholic beverage samples. However, it did not outperform the classical internal standard method in all parameters. That one gave better results for repeatability and linearity for the set of calibration solutions measured, despite the fact that each sample had to be pre-treated. It was also found that samples with a high ethanol or other volatile content were not suitable for SPME analysis, because the fibre then loses its ability to sorb these substances in the same proportions and...
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Determination of essential oils in hops and beer by GC-MS method
Přikryl, Jaroslav ; Sobotníková, Jana (advisor) ; Nesvadba, Vladimír (referee)
The submitted master's thesis aims to the analysis of hop essential oils using gas chromatography separation and subsequent determination using a pair of mass and flame ionization detectors. In the first part, the thesis focuses on the theoretical approach to the issue of hop essential oils and the technical functionality of the device for the detection and quantitative determination of essential oils. Subsequently, in the second part, work describes the development, optimization and validation of the newly developed method for the extraction and determination of hop essential oil.
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Extension of artificial intelligence DeepReI and its application in practice
Hurychová, Nikola ; Sobotníková, Jana (advisor) ; Křížek, Tomáš (referee)
Diploma thesis deals with expanding the artificial intelligence DeepReI with the prediction of retention indices of substances in gas chromatography for standard non-polar and polar stationary phases. The theoretical part describes artificial intelligence, convolutional neural networks, and the principles of neural network learning. There is also a brief overview of the applications of neural networks in analytical chemistry. In the experimental part, the original DeepReI model was extended to predict the retention indices of substances for standard non-polar and polar stationary phases. Furthermore, more accurate predictions of retention indices were achieved for semi-standard non-polar stationary phases compared to existing models. The applicability of the model for substance identification was verified through non-targeted analysis of non-alcoholic beers using gas chromatography with mass detection.
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