Males of South American fruit fly Anastrepha fraterculus form leks and release sex pheromone to attract females during the reproductive behavior. The aim of my diploma thesis was to collect samples of volatiles released by variously old males, subsequently to analyze and to determine the changes in the quantitative composition of the sex pheromone depending on age. The volatiles were trapped on adsorbent, eluted with hexane containing internal standard and analyzed by gas chromatography with mass detection. Males release twenty volatiles, including fourteen terpenes: α-pinene, camphene, -pinene, myrcene, Δ3-carene, limonene, (Z)--ocimene, (E)--ocimene, aromadendrene, trans-α-bergamotene, (Z)-β-farnesene, (Z,E)-α-farnesene, germacrene D, (E,E)-α-farnesene; one aldehyde: nonanal; two alcohols: (3Z)-non-3-en-1-ol, (3Z,6Z)-nona-3,6-dien-1-ol and three lactones: suspensolide, anastrephin a epianastrephin. From the list of named compounds there were proved antenal activity of six compounds in previous work, namely trans-α-bergamotene, (Z,E)-α-farnesene, (E,E)-α-farnesene, (3Z)-non-3-en-1-ol, (3Z,6Z)-nona-3,6-dien-1-ol and epianastrephin.

L'un des défis actuels de la chimie alimentaire est de développer des produits avec une qualité sanitaire et sensorielle optimale. Ceci est particulièrement important dans les produits traités thermiquement, tels que les produits céréaliers. Lors de la cuisson et à partir des ingrédients, un nombre considérable de composés peuvent se former. Certains suscitent une préoccupation sanitaire émergente, lorsque d'autres jouent un rôle sensoriel indéniable. Comprendre la réactivité des constituants devient alors un levier puissant pour développer des voies d'amélioration des aliments. Ce travail porte sur les effets des ingrédients et conditions de cuisson dans la génération de furane, composé possiblement cancérigène, et furfural, composé odorant contribuant à l'arôme caractéristique de la génoise. Afin de maîtriser la réactivité et ainsi optimiser la qualité des produits, une approche globale a été adoptée, incluant l'étude des composés volatils, des propriétés physicochimiques et sensorielles et l'appréciation hédonique des consommateurs. Ce travail propose une méthodologie et ouvre des pistes intéressantes pour développer des stratégies efficaces de maîtrise de la qualité globale des produits transformés. / A current challenge for food chemists consists in developing safe yet appealing food. This is particularly difficult in thermally-treated foods, like baked products, since a great number of compounds may be produced during heating. While some of these are of health concern, others contribute to other key aspects of quality, such as aroma or color, revealing the need of considering reactivity into food quality design. This work deals with the effects of formulation and baking conditions on the generation of furan, a heatinduced contaminant, and furfural, contributing typical aroma to sponge cake. Moreover, a holistic approach was adopted, covering volatile generation, physical properties, sensory evaluation and consumer tests, both for further understanding reactivity and optimizing product quality. This work is certainly an important step towards the development of novel strategies for qualitydriven design of heat-treated food.

Oxidation limits the shelf life of many food products. Adding antioxidants to foods is the most common way to solve this problem. Reports on safety issues of synthetic food additives have raised consumer interest in "all natural" foods, without added antioxidants or with synthetic replaced with natural antioxidants. The natural antioxidants now in use are much more expensive and less potent than the synthetic antioxidants. Thus, effective and economical natural antioxidants are of great interest to researchers. Teng Cha is a type of herbal tea found in China that has reported high levels of antioxidants. Antioxidant activity of Teng Cha extract and its major component dihydromyricetin has been reported, but no studies have provided clear evidence for the antioxidant effectiveness of Tech Cha extracts. The goal of this study was to measure the antioxidant activity of Teng Cha extract and dihydromyricetin (DHM), a major component of Tech Cha extract. The DPPH assay was conducted and antioxidant activities of the crude extract and dihydromyricetin were evaluated in soybean oil based on the peroxide value, anisidine value, Totox value, headspace volatiles and headspace oxygen. Antioxidant effectiveness was also evaluated in a cooked beef model system. DHM was more potent than BHA in preventing soybean oil oxidation. The crude extract was not as effective as BHA and DHM, possibly because it contained transition metals. In cooked beef, DHM and the crude extract showed lower activity than BHA, possibly due to their low solubility. Overall, Teng Cha extract and DHM are potential natural food antioxidants for future applications. / Master of Science in Life Sciences

The detection and identification of the oxygenated class of ignitable liquids is a complex issue for the fire debris analyst. The oxygenated compounds are difficult to recover using traditional analytical techniques since their chemical characteristics are vastly different from those of the petroleum products that compose the majority of the ignitable liquid classes. Previous research has demonstrated that the use of zeolite 13X as an adsorbent in heated passive headspace concentration provides increased recovery of oxygenated compounds in comparison to the conventional activated charcoal adsorbent. This hypothesis was further tested in this work using more realistic casework scenarios. Various carpet, carpet padding and wood types were utilized in a number of burn conditions in order to determine if any substrate interferences were present; as well as to monitor the recovery of oxygenated compounds from these substrates using the proposed zeolite extraction method. The substrates explored did not contribute significant background interference to complicate the identification of the oxygenated compounds. In addition, small volumes of the oxygenated ignitable liquids were easily recovered and identified from all burn states using the zeolite method. A dual-mode extraction with both zeolites and activated charcoal strips as adsorbents was utilized with mixtures of oxygenated compounds and petroleum products to determine if a variety of ignitable liquid classes could be detected and identified in the presence of a variety of substrate matrices within a single extraction protocol. The dual-mode extraction showed that both the oxygenated compounds and petroleum products could be detected and identified using a single extraction protocol in the presence of various substrate matrices. Lastly, an experiment was devised to compare the recovery of the oxygenated compounds using various total available surface areas of both zeolites and activated charcoal strips in order to determine which adsorbent exhibits a greater recovery when all other experimental conditions remain constant. When the surface areas were equalized between the zeolites and activated charcoal strips, the activated charcoal exhibited a greater recovery of the oxygenated compounds. However, the cost effectiveness of the zeolites allows for a greater amount of zeolite beads to be used in order to achieve the same recovery as the activated charcoal strips for a much lower price. Therefore, the findings from this work, in combination with previous research, continue to support the use of zeolite 13X as an alternative adsorbent for the recovery of oxygenated ignitable liquids from fire debris evidence.

A elevada incidência de acidentes de trânsito está fortemente relacionada ao consumo de bebidas alcoólicas. No Brasil a verificação do uso de álcool entre os condutores é realizada através dos etilômetros e da confirmação do etanol presente no sangue pela técnica de headspace (HS) associada à cromatografia em fase gasosa com detector de ionização de chama (CG/DIC). Não foram encontrados na literatura métodos para determinação de etanol em fluido oral (FO), utilizando a cromatografia em fase gasosa com detector de massas (CG/EM). Objetivos: Realizar a otimização da extração do etanol do fluido oral pela técnica de HS através de desenho experimental e posterior validação de metodologia analítica para a determinação de etanol em FO através de CG/EM e CG/DIC, utilizando o Quantisal® como dispositivo de coleta. Métodos: O desenho experimental foi desenvolvido através do Box–Behnken Design (BBD), onde foram avaliados a temperatura, o tempo de agitação e o volume injetado. O método foi validado de acordo com as recomendações do FDA e ANVISA considerando os parâmetros de seletividade, efeito residual, efeito matriz, linearidade, precisão, exatidão, limite de detecção e quantificação, estabilidade e recuperação. Resultados: As melhores condições do HS obtidas pelo desenho foram: temperatura de 90ºC, volume de injeção de 1000 μL e tempo de extração de 7 min. O método mostrou-se linear na faixa de 0,05-2 g/L (0,5-20 dg/L). Os valores de exatidão situaram-se na faixa de 101,56 e 111,29% e os valores obtidos para a precisão intra e interdia foram inferiores a 12%. Os limites de quantificação e de detecção encontrados foram iguais a 0,0125 g/L e 0,005 g/L para a CG/EM e 0,05 g/L e 0,0129 g/L para a CG/DIC, respectivamente. Conclusões: O método desenvolvido mostrou-se eficaz na determinação inequívoca de etanol em fluido oral através da técnica de HS-CG/EM e utilizando o dispositivo de coleta Quantisal®, atingindo limites de detecção inferiores ao encontrados pelas análises em CG/DIC, sem a necessidade de confirmação por outros sistemas cromatográficos e podendo ser facilmente aplicado na rotina laboratorial. / The high incidence of traffic accidents is strongly related to alcohol consumption. In Brazil the verification of alcohol use among drivers is performed through the breath alcohol analyzers and confirmation of ethanol in blood by the headspace technique (HS) associated to gas chromatography with flame ionization detector (GC/FID). To the best of our knowledge there are no methods for the determination of ethanol in oral fluid (OF), using gas chromatography with mass detection (GC/MS) in the literature. Propose: Perform the optimization of the extraction of ethanol from OF by headspace technique (HS) through experimental design and subsequent validation of analytical method for the determination of ethanol in OF by GC/MS and GC/DIC, using Quantisal® as a collection device. Methods: The experimental design was performed using the Box-Behnken Design (BBD) and the evaluated parameters were temperature, stirring time and sample volume injected. The methods were validated according to FDA and ANVISA recommendations considering the parameters of selectivity, residual effect, matrix effect, linearity, precision, accuracy, limit of detection and quantification, stability and recovery. Results: The best conditions of HS obtained by design were: temperature 90°C, injection volume 1000 μL and extraction time of 7 min. The method was linear in the range of 0.05-2 g/L (or 0.5-20 dg/L). The values of accuracy stay in the range of 101.56 and 111.29% and values for intra and inter-day precision were less than 12%. The limits of detection and quantification were found equal to 0.0125 g/L and 0.005 g/L for GC/MS and 0.05 g/L and 0.0129 g/L for GC/FID, respectively. Conclusions: The method was effective in unequivocal determination of ethanol in oral fluid by HS-GC/MS and using the collection device Quantisal®, reaching detection limits lower than that found by analysis on HS-GC/FID, without the need confirmation by other chromatographic systems and can be easily applied for routine monitoring.

Aldehydes in lung cancer cell culture have been investigated using gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization. In this study, the poly(dimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used and o-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) was first loaded on the fiber. Aldehydes in the headspace of lung cancer cell culture were extracted by solid-phase microextraction (SPME) fiber and subsequently derivatized by PFBHA on the fiber. Finally, the aldehyde oximes formed on the fiber were analyzed by gas chromatography/mass spectrometry (GC/MS). Using this method, acetaldehyde decrease was found in both non-small lung cancer cell cultures studied compared to the medium control study. The results of spiking the cell culture with acetaldehyde solution showed that 5 million SK-MES-1 cell lines could consume up to 4.5 uM acetaldehyde in 15-ml medium, and 5 million NCI-H522 cell lines could consume 5.9 uM acetaldehyde in 15-ml medium. The decrease of acetaldehyde may contribute to the metabolism of lung cancer cells. It was proved that GC/MS and SPME with on-fiber derivatization is a simple, rapid, sensitive and solvent-free method for the detection of aldehydes in lung cancer cell culture.

The determination of accurate volatile organic compound (VOC) and greenhouse gas (GHG) partitioning coefficients for air-water interfaces is essential for pollution and global climate modeling. In the atmosphere, oceans, and groundwater the concentration of dissolved salts is high enough to significantly alter the air-water partitioning behavior of the VOC or GHG, prohibiting the use of literature data or predictive models that omit the salt effect. Despite the great need for air-water partitioning data of the VOCs and GHGs threatening the environment, there is a lack of air-water partitioning data in the presence of dissolved salt. Furthermore, there are large disagreements between reported data from different research groups, which hamper model development. Henry s constants of several VOCs with salts were measured with a new high-throughput headspace gas chromatography (HTHSGC) method to create a library of internally consistent air-water partition coefficients for modeling. The VOCs studied included a homologous series of 1-alkanols, 2-ketones, organic sulfides, and the principle components of gasoline including: toluene, ethylbenzene, o-xylene, methyl tertbutyl ether, and ethyl tertbutyl ether. A model with temperature-independent parameters based on dilute solution theory was developed using the library of data to resolve the disagreements between literature sources and perform a priori prediction of salt effects. The model correlated air-water partitioning data in the form of Henry s constants over temperature ranges as wide as 300 Kelvin, salt concentrations up to 4 molal, and pressures up to 1000 bar. Extrapolations of up to 50 K, and 1 molal salt and 100 bar pressure can also safely be performed to eliminate the need for additional experiments. The temperature-independent salt effect parameter was found to be directly proportional to the critical volume of the VOC and all homologous VOCs explored followed the same linear trend allowing a priori prediction of the salt effect for unexplored compounds.

Aldehydes in lung cancer cell culture have been investigated using gas chromatography/mass spectrometry and solid-phase microextraction with on-fiber derivatization. In this study, the poly(dimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used and o-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) was first loaded on the fiber. Aldehydes in the headspace of lung cancer cell culture were extracted by solid-phase microextraction (SPME) fiber and subsequently derivatized by PFBHA on the fiber. Finally, the aldehyde oximes formed on the fiber were analyzed by gas chromatography/mass spectrometry (GC/MS). Using this method, acetaldehyde decrease was found in both non-small lung cancer cell cultures studied compared to the medium control study. The results of spiking the cell culture with acetaldehyde solution showed that 5 million SK-MES-1 cell lines could consume up to 4.5 uM acetaldehyde in 15-ml medium, and 5 million NCI-H522 cell lines could consume 5.9 uM acetaldehyde in 15-ml medium. The decrease of acetaldehyde may contribute to the metabolism of lung cancer cells. It was proved that GC/MS and SPME with on-fiber derivatization is a simple, rapid, sensitive and solvent-free method for the detection of aldehydes in lung cancer cell culture.

The objective of the present work was systematic investigation of water-based headspace single-drop microextraction (SDME) technique, its conjunction with capillary electrophoresis, and application for the analysis of volatile inorganic compounds (cyanide and ammonium) in biomedical and environmental samples. Theoretically evaluated and experimentally confirmed that the manipulation in the volatility of the analyte by its chemical modification in the sample and/or in the acceptor phase is the most effective way to enhance the extraction performance in headspace SDME. Maximum extraction efficiency for cyanide was observed in the pH range 4.5–7.5, where cyanide anion is completely transferred into volatile HCN. Complete cyanide recoveries (≥96%) from metal-cyanide complexes were obtained by using two ligand-exchange reagents (ethylenediamine and dithizone). Maximum extraction efficiency was observed by the extraction of ammonia from alkaline samples (pH≥11) with neutral or slightly acidic acceptor phase (pH 3-7). Compared to existing methods water-based headspace SDME is significantly faster and simpler. In addition, proposed technique does not require any sample pre-treatment (deproteinization, acidic/alkaline distillation, etc.) and thus is much less susceptible to interferences. Finally, it offers possibility to choice of a wider variety of solvents and, consequently, enhances the range of extractable analytes as well as the range of analytical methods that can be coupled... [to full text] / Daktaro disertacijoje nuodugniai ištirtas mikroekstrakcijos iš viršerdvės vandens lašu metodas, apjungtas su kapiliarine elektroforeze bei pritaikytas lakių neorganinių junginių (cianido ir amonio) koncentravimui ir nustatymui biomedicininiuose ir aplinkos objektuose. Teoriniais skaičiavimais parodyta ir eksperimentiškai patvirtinta, kad efektyviausias būdas mikroekstrakcijos iš viršerdvės efektyvumui pagerinti – analitės lakumo didinimas chemiškai modifikuojant ją prieš ekstrakciją ir/arba jos lakumo mažinimas modifikuojant ją akceptorinėje fazėje. Maksimalus cianido mikroekstrakcijos efektyvumas pasiekiamas pH srityje 4,5- 7,5, kur cianidas kiekybiškai pervedamas į lakų HCN. Ištyrus cianido mikroekstrakciją tirpiklio lašu iš metalų cianidinių kompleksų tirpalų nustatyta, kad kiekybiškas silpnai surišto cianido suardymas (cianido išgavos siekia ≥96%) pasiekiamas panaudojus ligandų mainus etilendiamino ir ditizono mišiniu. Maksimalus amonio mikroekstrakcijos efektyvumas pasiekiamas ekstrahuojant jį iš pašarmintų mėginių (pH≥11) akceptorine faze, kurios pH 3-7. Lyginant su standartiniais metodais, siūlomas metodas yra greitesnis ir paprastesnis, visiškai eliminuojama mėginio matricos įtaka, nereikalingos jokios drastiškos (deproteinizacija, veikimas rūgštimis/šarmais, distiliacija ir pan.) manipuliacijos su mėginiu, todėl išvengiama mėginio matricos įtakos. Mikroekstrakcija iš viršerdvės vandens lašu praplečia mikroekstrakcijos metodų taikymo sritis: atveriama galimybė labai... [toliau žr. visą tekstą]

Universiẗat, Diss., 2003--Bonn.