Lake Vättern has been contaminated with high levels of polychlorinated biphenyls (PCBs) for decades, which could be due to the release of wastes from industries and urban communities surrounding the water system. This has especially had a negative effect on fatty fishes, which could accumulate large amounts of persistent organic pollutants (POPs) and thereby also become a source of environmental toxicants to humans through consumption. Most PCB analysis only quantify a handful of congeners, the so called indicator-PCBs (I-PCBs), but this might leave out important information. In this study, an existing analytical method was improved by supplementing with additional congeners to detect a larger set of PCB congeners in Arctic char (Salvelinus salvelinus) and European whitefish (Coregonus acronius) caught from Lake Vättern, Sweden. New pre-packed multilayer silica columns from CAPE technologies were tested and used to pretreat the fish samples prior to analysis with a Gas Chromatograph coupled to low-resolution Mass Spectrometer using Atmospheric Pressure Ionization (API GC/MS). It was found that modifications of the clean up method for PCBs were necessary, such as lowering the amount of hexane in the washing step and combining the two eluent fractions. The Arctic char and the European whitefish showed a fat content of 0.18% and 0.74%, respectively. Concentrations of detected congeners ranged from 0.5 to 1470 pg g-1 fresh weight (fw) in Arctic char and varied between 1.2 to 6550 pg g-1 in European whitefish. For Arctic char and European whitefish, the WHO2005-TEQ values were 0.4 pg g-1 fw and 0.6 pg g-1 fw, respectively. The greatest total PCB concentration of 25900 pg g-1 was measured in European whitefish. The total concentration of I-PCBs (#28, 52, 101, 138, 153, 180) was 3710 pg g-1 for the Arctic char and 13900e pg g-1 for the European whitefish. All obtained results were lower than those reported from other studies. Constructed congener profiles show that the two species have similar ratios of PCB #138 and #153. Differences are observed of PCBs with a higher chlorination grade, probably due to differences in migration patterns, habitats of the lake, diets, metabolism or bioaccumulation.

The thesis has focused on the separation of proanthocyanidins (Pas) in beer, raw beer material and beer intermediates (wort, hopped wort, green beer) by using high performance liquid chromatography coupled to high resolution mass spectrometric detection. A chromatographic column XSELECT HSS T3 was used for separation of individual proanthocyanidins. Mobile phase was formed by a mixture of 0,1% formic acid in water (A) and 0,1% formic acid in acetonitril (B), separation was conducted in gradient mode. Calibration range for catechin and procyanidin B1 a B2 was linear in the range from 10 µg.l-1 to 200 µg.l-1 and for epicatechin from 5 µg.l-1 to 200 µg.l-1 . Limit of quantitation (LOQ) was set to the lowest point of calibration curve, hence for catechin, procyanidin B1 and B2 was LOQ = 10 µg.l-1 and for epicatechin was LOQ = µg.l-1 . Yield of method of the observed Pas was very good, where yield oscillated around 100%. The method also had excellent repeatability, where the relative standard deviation (RSD) was lower then 20%. After optimization of this method it was used for observation of profile changes during brewery process in catechin, epicatechin, procyanidin B1, B2 and B3. It was discovered, that catechin, epicatechin, procyanidin B1 and B2 originate mainly from hops and procyaniding B3 is...

Microelectromechanical systems (MEMS) technology allows the realization of mechanical parts, sensors, actuators and electronics on silicon substrate. An attractive utilization of MEMS is to develop micro instruments for chemical analysis. An example is gas chromatography (GC) which is widely used in food, environmental, pharmaceutical, petroleum/refining, forensic/security, and flavors and fragrances industries. A MEMS-based micro GC (µGC) provides capabilities for quantitative analysis of complex chemical mixtures in the field with very short analysis time and small amounts of consumables. The aim of this research effort is to enhance the sensitivity and selectivity of µGC instruments by implementing chemical amplification method known as preconcentration. A micro preconcentrator (µPC) extracts the target analytes from the sample matrix, concentrates them, and injects them into the separation column for analysis. This work resulted in the development of silicon-glass bonded chips consisting of 7 mm x 7 mm x 0.38 mm multiport cavity with thousands of embedded 3D microstructures (to achieve high surface-to-volume ratio) coated with polymeric thin film adsorbents. Deep reactive ion etching (DRIE) was the enabling technology for the realization of µPCs. Several coating methods, such as inkjet printing of polymers and polymer precipitation from solution have been utilized to coat complex geometrical structures. One major outcome was the development of cobweb adsorbent structure. Moreover, the porous polymeric adsorbent Tenax TA in the film form was characterized, for the first time, for μPC application and shown to have similar properties to that of the granular form. Several μPC designs were experimentally evaluated for their performance in concentrating volatile organic compounds, including cancer biomarkers, Propofol (anesthetic agent), environmental pollutants, and chemical warfare simulants. The possibility of utilizing the μPCs in practical applications such breath analysis was also demonstrated. / Ph. D.

A aplicação do processo de fotoeletrocatálise à eliminação de interferentes orgânicos em baixa concentração na eletroanálise de metais foi abordada tomando o quelato Cu(II)-EDTA como sistema modelo e o restabelecimento da onda voltamétrica do cobre como indicador de efetividade. Desenvolveram-se células eletroquímicas de camada delgada (espessura de 600 micrômetros) nas quais alguns microlitros de amostra são tratados sobre um eletrodo modificado com TiO2 (tipo P25, rico em anatase), cuja superfície é irradiada através de uma janela por um LED (370 nm). Foram construídos e avaliados os seguintes eletrodos: pasta de carbono, TiO2 e óleo parafínico (CPE-TiO2), compósitos de grafite, TiO2 e adesivo epóxi ou de silicone e ouro com oclusão de TiO2 por eletrodeposição. Estudo do efeito de parâmetros como potencial aplicado ao eletrodo, composição do eletrólito e concentração de EDTA sobre a fotocorrente permitiu selecionar condições de trabalho e estabelecer algumas correlações. Por exemplo, observou-se linearidade entre a fotocorrente e a concentração de EDTA até 1,0 mmol/L, aparente limite superior do controle difusional do processo para potência radiante aplicada, acima do qual, a cinética de oxidação passa a sobrepujar o transporte no controle da velocidade de reação. O restabelecimento pleno da onda de Cu(II) 1,0 mmol.L-1 foi observado após a irradiação por 10 min quando a concentração de EDTA não excedia 0,94 mmol.L-1. Descobriu-se um procedimento mais rápido que consiste na aplicação do tratamento fotoeletrocatalítico simultâneo ao registro de voltamogramas cíclicos repetitivos (eletrodo de Au-TiO2, 0,3 a 0,7 V vs. Ag/AgCl, 100 mV.s-1). Após o sexto ciclo, a altura do pico de redissolução anódica do Cu (reduzido durante a varredura no sentido negativo) estabiliza, permitindo a quantificação sem etapa prévia de abertura. / The photoelectrocatalysis process was investigated for the elimination of organic compounds interference on the electroanalysis of trace metals. Cu(II)-EDTA chelate was chosen as model system and the recovery of copper voltammetric peak, as effectiveness indicator. Thin layer cells (thickness of 600 micrometers) were designed for the treatment of some microliters of sample by irradiation (370 nm LED) of an electrode modified with TiO2 (P25, anatase rich). The following modified electrodes were prepared and evaluated: carbon paste with TiO2 and paraffin oil (CPE-TiO2), composites of graphite, TiO2 and epoxy or silicone binders and TiO2 occluded in electrodeposited gold on a gold substrate. The effect of parameters like potential bias, electrolyte composition and EDTA concentration on the photocurrent was evaluated to setup working conditions. Some correlations were observed, e.g., a linear dependence between photocurrent and EDTA concentration up to 1.0 mmol/L. For the irradiance applied, this concentration is possibly the upper limit of operation diffusion transport control, above which, the kinetics of the oxidation at the TiO2 modified electrode becomes the controlling process. For EDTA concentrations not exceeding 0.94 mmol.L-1, full recovery of 1.0 mmol.L-1 Cu(II) voltammetric peaks was observed after 10 min of irradiation. A faster procedure was discovered and consists in recording repetitive cyclic voltammograms (Au-TiO2 electrode, 0,3 to 0,7 V vs. Ag/AgCl scans, 100 mV.s-1) simultaneously with continuous irradiation. After the sixth cycle, the copper anodic stripping peak height stabilizes allowing quantification without previous sample pre-treatment step.

A aplicação do processo de fotoeletrocatálise à eliminação de interferentes orgânicos em baixa concentração na eletroanálise de metais foi abordada tomando o quelato Cu(II)-EDTA como sistema modelo e o restabelecimento da onda voltamétrica do cobre como indicador de efetividade. Desenvolveram-se células eletroquímicas de camada delgada (espessura de 600 micrômetros) nas quais alguns microlitros de amostra são tratados sobre um eletrodo modificado com TiO2 (tipo P25, rico em anatase), cuja superfície é irradiada através de uma janela por um LED (370 nm). Foram construídos e avaliados os seguintes eletrodos: pasta de carbono, TiO2 e óleo parafínico (CPE-TiO2), compósitos de grafite, TiO2 e adesivo epóxi ou de silicone e ouro com oclusão de TiO2 por eletrodeposição. Estudo do efeito de parâmetros como potencial aplicado ao eletrodo, composição do eletrólito e concentração de EDTA sobre a fotocorrente permitiu selecionar condições de trabalho e estabelecer algumas correlações. Por exemplo, observou-se linearidade entre a fotocorrente e a concentração de EDTA até 1,0 mmol/L, aparente limite superior do controle difusional do processo para potência radiante aplicada, acima do qual, a cinética de oxidação passa a sobrepujar o transporte no controle da velocidade de reação. O restabelecimento pleno da onda de Cu(II) 1,0 mmol.L-1 foi observado após a irradiação por 10 min quando a concentração de EDTA não excedia 0,94 mmol.L-1. Descobriu-se um procedimento mais rápido que consiste na aplicação do tratamento fotoeletrocatalítico simultâneo ao registro de voltamogramas cíclicos repetitivos (eletrodo de Au-TiO2, 0,3 a 0,7 V vs. Ag/AgCl, 100 mV.s-1). Após o sexto ciclo, a altura do pico de redissolução anódica do Cu (reduzido durante a varredura no sentido negativo) estabiliza, permitindo a quantificação sem etapa prévia de abertura. / The photoelectrocatalysis process was investigated for the elimination of organic compounds interference on the electroanalysis of trace metals. Cu(II)-EDTA chelate was chosen as model system and the recovery of copper voltammetric peak, as effectiveness indicator. Thin layer cells (thickness of 600 micrometers) were designed for the treatment of some microliters of sample by irradiation (370 nm LED) of an electrode modified with TiO2 (P25, anatase rich). The following modified electrodes were prepared and evaluated: carbon paste with TiO2 and paraffin oil (CPE-TiO2), composites of graphite, TiO2 and epoxy or silicone binders and TiO2 occluded in electrodeposited gold on a gold substrate. The effect of parameters like potential bias, electrolyte composition and EDTA concentration on the photocurrent was evaluated to setup working conditions. Some correlations were observed, e.g., a linear dependence between photocurrent and EDTA concentration up to 1.0 mmol/L. For the irradiance applied, this concentration is possibly the upper limit of operation diffusion transport control, above which, the kinetics of the oxidation at the TiO2 modified electrode becomes the controlling process. For EDTA concentrations not exceeding 0.94 mmol.L-1, full recovery of 1.0 mmol.L-1 Cu(II) voltammetric peaks was observed after 10 min of irradiation. A faster procedure was discovered and consists in recording repetitive cyclic voltammograms (Au-TiO2 electrode, 0,3 to 0,7 V vs. Ag/AgCl scans, 100 mV.s-1) simultaneously with continuous irradiation. After the sixth cycle, the copper anodic stripping peak height stabilizes allowing quantification without previous sample pre-treatment step.

Analysis of biological samples can be a difficult task. This thesis covers a broad aspect of the analytical areas of capillary electrophoresis (CE) and capillary electrochromatography (CEC) in combination with mass spectrometry (MS) that are of great importance for achieving fast, accurate and sensitive bioanalyses. A significantly time reduced and automated system for sample cleanup was developed to greatly simplify the pretreatment process of biological samples with a complex matrix. Desalting and preconcentration of species in urine was conducted and the limit of detection for the antidepressant escitalopram was lowered 10 times. This extraction devise was also successfully incorporated in a chip based platform for the possibility to be a part of multidimensional separation systems. The reduced risk of sample loss leads to improved detection limits, which are usually one the most challenging parts when working with bioanalyses. In the area of separation, a monomer surface with tailored hydrophobicity was developed to achieve rapid, high efficient separations of complex mixtures. Within five minutes a tryptic digest of a protein could be separated and then identified by a Mascot search. The applications addressed have been focused on medical conditions which are of highest interest for both physicians and patients. A high throughput analysis of the kynurenine metabolites with CE-MS offers a new method to rapidly examine samples from patients with neurological disorders. A screening study of possible biomarkers for the two different types of appendicitis, gangraenous and phlegmonous was conducted. Indicative patterns were found for both pre and post surgery of the two types of inflammation as well as between them. The divergences were traced back to the MS peaks obtained in the CE- and CEC-MS setups as possible biomarkers for the two forms of appendicitis. A preliminary study of polycystic ovary syndrome also offered some valuable results for future biomarker identification.

The theoretical part of the thesis deals with the chemical composition of cow’s milk, with the description of chosen methods of sample pretreatment and with the description of the used technique ICP-OES. The practical part is aimed at individual preparations of samples and at analysis of chosen chemical elements (Ca, Na, K and Mg). Milk is a really complicated polydisperse system, that’s the reason why the preparation of samples with milk is very important step before the measurement itself. In addition to accuracy choosing the sample adjustment method, other factors such as time, work intensity, or cost need to be considered when. In the thesis a comparison of four selected methods of sample preparation was made: direct analyse of milk, dilution with addition of Triton X-100, wet microwave ashing and destruction of matrix with TMAH (tetramethylammonium hydroxide). Selected elements were analysed with the help of ICP-OES. This diploma thesis builds on the bachelor thesis, which deals with the same problem. Final concentrations were compared with certified values of skimmed powdered milk. Data showed that the most accurate are methods of preparation of wet microwave ashing and destruction of matrix with TMAH. By using these methods, the effect of the dairy matrix that caused problems in the analysis, was largely eliminated. The diluted samples with and without Triton X-100 showed a bigger anomaly of measuring than the mineralization of wet ashing which came to the loss of analyte because of fat elements contained in milk.