Stem constitutes approximately from 3 to 5 percent of total weight of a grape. The chemical structure of stem is mainly related to a variety, habitat conditions and ripeness. Stem consists from 35 to 90 percent of water, it also consists of sugar, tartaric acid and malic acid, tannins and vegetable dyes. In the production proccess of making wine, stem is perceived only as a residual part and there is a fact often omitted that stem is not only an integral part of grapes but it is also an indicator to the presence of a disease on the Vitis vinifera. Although stems have a drainage effect, they are improper for the production of wine itself, because the green stems in the stum cause the objectionable taste of grass. The first part of the thesis contains the general informations about stem: its composition, detailed description of the most contained substances and possibilities of the use of stem as well. My thesis also contains of detailed descripted spectrometric and chromatografic analysis and results as a part of the conducted research on substances contained in stem. In the last part of the thesis there are proccesed facts using the search method. They are mainly derived from foreign literature and are divided to several chapters: comparison of the derived results with international studies, new technologies that evaluate the substances contained in stem and also the effects of stem on human health.

This thesis deals with the effect of storage of cannabis on the level of content of its active substances. The theoretical portion focuses on a botanical characteristics sum-mary. It further describes the growing needs and options of cannabis on the fields and of medical cannabis in covered areas. Portion of the thesis deals with the use of each individual parts of the cannabis plant. The thesis contains detailed description of canna-binoids and other substances. It further describes the effect of individual external factors on the stability of cannabinoids in cannabis products. The last part of the theore-tical section deals with the ability to analyze cannabinoids. The goal of the experimental section was to discover effects of different type of storage on the level of content of cannabidiol and delta-9-tetrahydrocannabinol in cannabis samples. The setting included a gas chromatograph GC Fisons instruments with FID detector. These samples were regularly collected and ex-tracted during the period of one year. Retention periods of individual cannabinoids and calibration curves were created. The results showed a reduction of cannabinoids in higher temperatures. The results further confirmed storage of vacuumed materials at -20 °C temperature as the most appropriate type of storage for female inflorescence of can-nabis.

The aim of the study was monitoring of two of phthalic acid esters in agricultural soils in the Czech Republic for free years: dibutyl phthalate (DBP) and di 2 ethylhexyl phthalate (DEHP). The monitoring of the phthalate content took place in twelve regions of the Czech Republic. Soil sampling was carried out using the zig-zag pattern from topsoil and subsoil. The soil samples were taken from the following cultures: arable land, permanent grassland and hop gardens. Concentration levels were established by means of high performance liquid chromatography with UV detection. Samples were extracted using sonication and mixture of acetone-hexane (1:1). The established concentrations of the esters of phthalic acid were as follows: for dibutyl phthalate from 0,02 to 1,78 mg.kg-1 dry weight; for di 2 ethyhexyl phthalate from 0,06 to 2,22 mg.kg-1 dry weight; total concentration of both phthalates then ranged from 0,24 to 2,83 mg.kg-1 dry weight. When comparing the concentration levels established in the present study with the values set by the Ministry of Environment of the Czech Republic and stated in its Guideline stemming from the RSL (Regional Screening Levels) published by the United States' Environmental Protection Agency (USEPA), none of these values were exceeded in this study.

The Master's thesis deals with the effect of feed enrichment with various types of oils on the deposition of fatty acids in selected tissues. Forty male Wistar Albino rats were divided into four groups and fed for 10 weeks daily ad libitum with a basic feed mixture enriched with 8 % palm, 8 % safflower, 8 % fish oil or 8 % microalgae Schizochytrium sp. oil. Rats had also free access to the drinking water. Fat from the tissue samples (liver, muscle, visceral fat) was extracted, converted to methyl esters and analyzed with usage of gas chromatography. The results of the experiment show that the addition of various types of oils to the feed of model organism can influence the deposition of fatty acids in its tissues. The addition of fish oil and microalgae Schizochytrium sp. oil caused statistically significant decrease (p < 0,05) in the ratio of PUFA n-6/n-3 in all observed tissues to a value of 1 or less compared to the addition of palm and safflower oil. Low ratio of n-6/n-3 polyunsaturated fatty acids is considered to be more desirable in reducing the risk of cardiovascular diseases.

The thesis is focused on application of ion chromatography in pharmaceutical analyses of organic ions. Ion chromatography is increasingly used in the field of pharmaceutical analysis. This includes the analysis of impurities and metabolites. In the first part of this thesis, ion chromatography is compared with common separation techniques used in pharmacy, such as gas chromatography and high performance liquid chromatography. In the second part development and validation of methods of ion chromatography for purity evaluation and quality control of active pharmaceutical substances Rivastigmine hemitartrate and Pramipexole hydrochloride were carried out. Key words: ion chromatography, reversed-phase chromatography, ion-pair chromatography, ion-exclusion chromatography, ion-exchange chromatography, GC, HPLC

The aim of this work was development of high-performance liquid chromatography method with DAD detection for determination of nicotine in tobacco. Standard operating procedure used by World Health Organization was chosen as comparison of the developed method. Optimized high performance chromatography method is suitable for determining nicotine in tobacco. Limit of detection for this method was 0,0003 mg/ml and limit of quantification was 0,0010 mg/ml. Optimization of preparation of samples was significant part of this thesis. Sample preparation procedure was made substantially easier in comparison to other commonly used methods. Nicotine content was determined from real tobacco leaves samples, cigarette tobacco filler, nicotine cartridge for electronic cigarettes and pipe tobacco. Satisfactory relative standard deviation was achieved for all types of samples. Next part of this thesis focused on study of determining polyphenols using high-performance liquid chromatography with diode array detector. Chosen analytes were chlorogenic acid, caffeic acid, rutine, scopoletine and quercitrine. Among the five tested analytes, the highest sensitivity was achieved for chlorogenic acid and caffeic acid. All of the analytes achieved low limits of detection and quantification. Key words Liquid chromatography,...

In frame work of this diploma thesis, monolithic stationary phases based on hydroxymethylmethacrylate were prepared in fused silica capillaries of 320 μm innerdiameter. Monolithic columns were synthesized by a simple procedure using a polymerization mixture, consisting of a monomer N-(hydroxymethyl) methacrylamide (HMMAA), a croslinking agent ethylene dimethacrylate (EDMA), porogenic solvents butane- 1,4-diol, propane-1-ol and an initiator α,α′-azobisisobutyronitrile (AIBN). Prepared HMMA monolithic columns were utilized for separation of mixtures of biologically active compounds, namely peptides with small number of amino acids. Mechanical strength and specific permeability were determined for selected monolithic columns. Keywords: HPLC, HILIC mechanism, hydroxymethyl methacrylate (HMMA) monolithic columns, amino acid, enkephalins.

This diploma thesis deals with the determination of glucosinolates in plant material by capillary electrophoresis and high performance liquid chromatography. The chemical structure, biosynthesis, degradation, and also biological effects of glucosinolates are described. One part of this work also deals with the methods, which glucosinolates in plant materials were determined by. The experimental part describes the separation of intact glucosinolates by capillary electrophoresis and high performance liquid chromatography. Two plant materials were available for the determination of glucosinolates, namely lyophilized rapeseed leaves and broccoli juice. Micellar electrokinetic chromatography using a cationic surfactant was used to determine intact glucosinolates by capillary electrophoresis. After finding the optimal conditions for the separation of intact glucosinolates, it was found that it is impossible to determine these substances in plant samples. The reason was interference from the matrix, which interfered with this determination. While using high performance liquid chromatography under optimal conditions, some of the intact glucosinolates were identified in a rapeseed plant sample. Furthermore, the calibration dependencies of individual glucosinolates were obtained and the recovery and...

New liquid phase microextraction (LPME) has been optimized. Plastic adapter with tapered tip was used as extraction device. Concentration of analytes was determined by GC-MS. Face centered design was used to optimize LPME and the results were evaluated by Minitab 16 programme. Volume of sample, volume of extraction solvent, stirring rate, extraction time, ionic strength and time after microextraction were optimized. Response of system was defined as the sum of the peak relative areas. Toluene, tetrachlorethylene, ethylbenzene, xylenes, mesitylene and naphthalene were the studied analytes. Methylhexadecanoate was used as an internal standard. Optimal system conditions were as follows: 20 mL sample volume, 300 μL extraction solvent volume, 20 minutes, stirring speed 700 rpm, no addition of salt, and time after microextraction 3.5 minutes. Determination coefficient was 0.9700 and the lack-of-fit was insignificant which indicated good agreement of the model with the experimental data. The preconcentration factor ranged from 26 (tetrachlorethylene) to 39 (xylenes). The microextraction yield was varied from 39.5% (tetrachlorethylene) to 59.1% (p-xylene and m-xylene). The new method was tested by analyzing real samples of tap water, river water and water from the sewage treatment plant. The samples were...

Proefschrift Rijksuniversiteit Groningen. / Met lit.opg. - Met samenvatting in het Nederlands.