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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.
11

Desenvolvimento de método de triagem de substâncias psicoativas em amostras de cabelo através de técnicas imunológicas / Development of screening method for the detection of psychoactive substances in hair samples using immunological techniques.

Roveri, Flávia Lopes 07 February 2017 (has links)
O consumo abusivo de substâncias psicoativas é um problema de saúde pública, sendo as análises toxicológicas uma importante ferramenta para seu controle. Atualmente, o cabelo está entre as mais utilizadas matrizes biológicas para análise de substâncias psicoativas, devido principalmente ao seu amplo período de deteção. As análises toxicológicas de drogas de abuso podem ser conduzidas através de técnicas de triagem seguidas por técnicas confirmatórias para os resultados positivos. No presente trabalho, foi avaliada a adaptação do método de triagem para substâncias psicoativas em cabelo a partir do kit para imunoensaio em sangue DOA I WB P com a tecnologia Biochip - Randox Laboratórios®. As análises foram realizadas para as classes das anfetaminas, benzodiazepínicos, barbitúricos, cocaína, opiáceos e canabinoides. Os ensaios imunológicos seguiram a partir da análise de amostras reais, adicionadas e artificiais sendo todas previamente confirmadas por técnica de cromatografia em fase gasosa acoplada à espectrometria de massas (GC-MS). Pelos resultados obtidos pôde-se observar que o kit não apresenta capacidade de analisar a classe de canabinoides. Já para os opiáceos, barbitúricos e anfetamina a aplicação do imunoensaio se mostrou promissora, entretanto a falta de amostras reais positivas impossibilitou a validação do método. Para cocaína, possíveis fontes de contaminação podem ter alterado os resultados impossibilitando a sua avaliação. Benzodiazepínicos, MDMA e metanfetamina apresentaram efeito matriz significativo, não havendo diferenciação entre amostras positivas e negativas. Desta forma, a validação e aplicação do método de imunoensaio para amostras de cabelo não foi possível devido ao elevado efeito de matriz apresentado pelo kit e a falta de amostras reais positivas impossibilitando a validação de parâmetros como sensibilidade, especificidade e exatidão. / The abuse of psychoactive substances is a public health problem and toxicological analysis is an important tool for its control. Currently, hair is among the most widely used biological matrices psychoactive substance analysis, mainly for its detection window. The toxicological analysis of drugs of abuse may be conduted by screening techniques followed by confirmation techniques for positive results. In the present work, an adaptation of a screening method for psychoactive substances in hair was evaluated from the DOA I WB P blood immunoassay kit with a Biochip - Randox Laboratories® technology. The analysis were performed for the drug classes of amphetamines, benzodiazepines, barbiturates, cocaine, opiates and cannabinoids. The immunological assays followed the analysis of real, spiked and artificial samples that have been previously confirmed by gas chromatography coupled to mass spectrometry (GC-MS) technique. From the results obtained it was observed that the kit does not sufficient capacity for analysis of cannabinoids. As for opiates, barbiturates and amphetamines, the immunoassay application proved to be promising. However, a lack of real samples made it impossible to validate the method. For cocaine, finding sources of contamination may have altered the results, making it impossible to evaluate. Benzodiazepines, MDMA and methamphetamine showed significant matrix effect, with no difference between positive and negative samples. Thus, a validation and application of the immunoassay method for hair samples was not possible due to the high matrix effect for the kit and a lack of actual samples making it extremely difficult to validate parameters such as sensitivity, specificity and accuracy.
12

Desenvolvimento de método de triagem de substâncias psicoativas em amostras de cabelo através de técnicas imunológicas / Development of screening method for the detection of psychoactive substances in hair samples using immunological techniques.

Flávia Lopes Roveri 07 February 2017 (has links)
O consumo abusivo de substâncias psicoativas é um problema de saúde pública, sendo as análises toxicológicas uma importante ferramenta para seu controle. Atualmente, o cabelo está entre as mais utilizadas matrizes biológicas para análise de substâncias psicoativas, devido principalmente ao seu amplo período de deteção. As análises toxicológicas de drogas de abuso podem ser conduzidas através de técnicas de triagem seguidas por técnicas confirmatórias para os resultados positivos. No presente trabalho, foi avaliada a adaptação do método de triagem para substâncias psicoativas em cabelo a partir do kit para imunoensaio em sangue DOA I WB P com a tecnologia Biochip - Randox Laboratórios®. As análises foram realizadas para as classes das anfetaminas, benzodiazepínicos, barbitúricos, cocaína, opiáceos e canabinoides. Os ensaios imunológicos seguiram a partir da análise de amostras reais, adicionadas e artificiais sendo todas previamente confirmadas por técnica de cromatografia em fase gasosa acoplada à espectrometria de massas (GC-MS). Pelos resultados obtidos pôde-se observar que o kit não apresenta capacidade de analisar a classe de canabinoides. Já para os opiáceos, barbitúricos e anfetamina a aplicação do imunoensaio se mostrou promissora, entretanto a falta de amostras reais positivas impossibilitou a validação do método. Para cocaína, possíveis fontes de contaminação podem ter alterado os resultados impossibilitando a sua avaliação. Benzodiazepínicos, MDMA e metanfetamina apresentaram efeito matriz significativo, não havendo diferenciação entre amostras positivas e negativas. Desta forma, a validação e aplicação do método de imunoensaio para amostras de cabelo não foi possível devido ao elevado efeito de matriz apresentado pelo kit e a falta de amostras reais positivas impossibilitando a validação de parâmetros como sensibilidade, especificidade e exatidão. / The abuse of psychoactive substances is a public health problem and toxicological analysis is an important tool for its control. Currently, hair is among the most widely used biological matrices psychoactive substance analysis, mainly for its detection window. The toxicological analysis of drugs of abuse may be conduted by screening techniques followed by confirmation techniques for positive results. In the present work, an adaptation of a screening method for psychoactive substances in hair was evaluated from the DOA I WB P blood immunoassay kit with a Biochip - Randox Laboratories® technology. The analysis were performed for the drug classes of amphetamines, benzodiazepines, barbiturates, cocaine, opiates and cannabinoids. The immunological assays followed the analysis of real, spiked and artificial samples that have been previously confirmed by gas chromatography coupled to mass spectrometry (GC-MS) technique. From the results obtained it was observed that the kit does not sufficient capacity for analysis of cannabinoids. As for opiates, barbiturates and amphetamines, the immunoassay application proved to be promising. However, a lack of real samples made it impossible to validate the method. For cocaine, finding sources of contamination may have altered the results, making it impossible to evaluate. Benzodiazepines, MDMA and methamphetamine showed significant matrix effect, with no difference between positive and negative samples. Thus, a validation and application of the immunoassay method for hair samples was not possible due to the high matrix effect for the kit and a lack of actual samples making it extremely difficult to validate parameters such as sensitivity, specificity and accuracy.
13

Langzeitnachweis anaboler Steroidhormone / Long-term detection of anabolic steroids

Anielski, Patricia 28 December 2007 (has links) (PDF)
Die missbräuchliche Anwendung von anabolen Substanzen erfolgt mit dem Ziel eines verstärkten Muskelaufbaus - im Sport zur Leistungsverbesserung, in der Tierzucht zum Erreichen von Zuchtidealen oder bei der Masttierhaltung zur Produktivitätssteigerung. Bisher wurden Doping- oder Medikationskontrollen zum Nachweis von anabolen Steroidhormonen üblicherweise im Urin bzw. im Blut durchgeführt. Für bestimmte Fragestellungen kann der analysierbare Zeitraum allerdings unzureichend sein oder aber die Untersuchungsmaterialien sind unter praktischen Gegebenheiten nur eingeschränkt verfügbar. Das Sammeln von Urinproben ist beispielsweise bei Zuchthengsten nur mit einem unverhältnismäßig hohen Aufwand realisierbar. Haare stellen in solchen Situationen eine Alternative dar, da sich das Entnahmeverfahren unkompliziert gestaltet und bei einer entsprechenden Haarlänge die eingelagerten Fremdstoffe länger als in Urin- oder Blutproben detektierbar sein sollten. In der vorliegenden Arbeit wurde ein effektiver Langzeitnachweis für insgesamt 11 anabole Substanzen in Pferdehaar-Proben mittels GC-HRMS und GC-MS/MS entwickelt (Nachweisgrenzen zwischen 0,1 und 5,0 pg/mg). Dabei können zum einen körperfremde anabole Wirkstoffe (z. B. Steroidester in Depotpräparaten) und zum anderen körper-eigene Steroide analysiert werden (z. B. Testosteron und Nandrolon beim Hengst). In verschiedenen Applikationsversuchen wurde gezeigt, dass durch eine Haaranalyse der Nachweis bis zu einem Jahr möglich ist. Für die endogene Nandrolonmenge in Schweifproben von unbehandelten Hengsten wurde eine signifikante Altersabhängigkeit festgestellt. Die ermittelten physiologischen Höchstkonzentrationen für Nandrolon betragen zwischen 1,1 pg/mg bei Junghengsten (1-3 Jahre) und 3,1 pg/mg bei Althengsten (11-20 Jahre). Die Bestimmung von Nandrolon in Haarproben erwies sich für die Körungskontrollen bei Junghengsten als ein geeignetes Verfahren zur Detektion einer exogenen Zufuhr. Die Untersuchung von Haaren ist zum Langzeitnachweis als Alternative gegenüber Blut- und Urinanalysen vorzuziehen, auch wenn sich retrospektiv nicht alle Fragen zum Behandlungsablauf präzise klären lassen (z. B. Angaben zur Dosierung oder zum genauen Applikationszeitpunkt). Das neu etablierte Verfahren ist außerdem die Methode der Wahl, wenn die Verfügbarkeit der übrigen Probematerialien eingeschränkt bzw. eine einfache und schnelle Beprobung erforderlich ist. Es wird bereits zur Medikationskontrolle bei Zuchthengsten sowie bei speziellen forensischen Untersuchungen eingesetzt.
14

Evaluation of methodology for mercury exposure assessment with field and laboratory studies

Legrand, Melissa January 2005 (has links)
The threat of environmental mercury (Hg), particularly methylmercury (MeHg), exposure to the health of humans has been well documented. Thus, it is important to monitor exposure and body burden for public health protection. The first objective of this thesis was to characterize the risk of Hg exposure in two Canadian coastal communities: Grand Marian (n = 91) and St. Andrews/St. Stephen (n = 52), New Brunswick, Canada, using dietary questionnaires and hair analysis. Average Hg intakes and body burden were below the most conservative guidelines. We attributed these results to the low Hg concentrations found in the species commonly consumed: haddock, canned tuna, lobster and pollock (all below 0.2 mg/kg). The analytical method employed to determine Hg in hair, cold vapor atomic absorption (CV-AAS), required a bundle of 100-150 hair strands and involved lengthy chemical digestion procedures which reduce throughput. Direct solid introduction techniques minimize these weaknesses. Our second and third objectives were to evaluate two such methods: (1) combustion, gold amalgamation, atomic absorption spectrometry (C-GA-AAS) and (2) laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for measuring total Hg in single hair strands. Hair samples with a wide range of Hg exposure were obtained from communities. A 1:1 relationship was observed between C-GA-AAS and the established CV-AAS for analysis of 1-cm hair segments. Additionally, the average relative standard deviation (RSD) of Hg between hair strands within an individual was 6.5 +/- 2.8%, thus justifying the use of a single hair strand for biomonitoring. With a limit of quantification of 0.10 ng of total Hg, a single hair strand with average weight of 0.5 mg and Hg concentrations of 0.2 mg/kg can be measured routinely. Using LA-ICP-MS, we showed that a single laser shot can sample hair material within 50 mum along a single hair strand which is equivalent to less than one day of
15

Evaluation of methodology for mercury exposure assessment with field and laboratory studies

Legrand, Melissa January 2005 (has links)
No description available.
16

Ethylglucuronid in Haaren

Ammann, Dominic 21 November 2017 (has links)
Obwohl EtG seit dem Jahr 2000 intensiv als Alkoholmarker in Haaren beforscht wird, bietet die Thematik weiterhin Raum für Forschung, insbesondere im Bereich der instrumentellen Analytik. Ziel der vorliegenden Arbeit ist die Beleuchtung dieser und weiterer Aspekte. Die Extraktion erfolgte überwiegend mittels der sogenannten Mikropulverisierung. Sie ermöglichte die simultane Mahlung der Haarmatrix und Extraktion des EtGs mit einem hohen Probendurchsatz. Die Selektion und anschließende Detektion erfolgte überwiegend durch HPLC-MS/MS. Die Sicherheit bei der Bestimmung des Analyten wurde durch die erfolgreiche Teilnahme an drei Ringversuchen der Society of Hair Testing (SoHT) belegt. Wiederholbedingungen wurden durch Herstellung von eigenen Haarreferenzmaterialien und die Verwendung von homogenen Fremdhaarmaterialien sichergestellt. Zur Evaluierung der Stabilität von EtG wurden zwei Haarmaterialien unter thermischen Stressbedingungen eingelagert und mit dem Gehalt von Referenzproben verglichen. Der Analyt zeigte außergewöhnliche Stabilität unter den gewählten Bedingungen. Ebenso erfolgte eine Beurteilung des Zerstörungsgrads von EtG im Haar durch oxidierende Substanzen, einhergehend mit der Entwicklung eines zerstörungsfreien Schnelltests mittels FTIR zur Detektion von oxidierten Cysteinspezies in Haaren. Das Modellsystem Barthaar wurde für zwei Experimentreihen etabliert: die Korrelation des EtG-Gehaltes im Barthaar nach Aufnahme definierter Alkoholmengen und den Nachweis von glucuronidierten Spezies im Barthaar nach Aufnahme der korrespondierenden Muttersubstanzen. Während keine eindeutige Korrelation zwischen aufgenommener Alkoholmenge und EtG-Gehalt im Barthaar hergestellt werden konnte, war es durchaus möglich, zwei glucuronidierte Metabolite von Arzneistoffen im Barthaar nach Konsum der Ausgangssubstanzen nachzuweisen. / Although EtG is subject to extended research since the year 2000, the topic still holds headroom for further experiments, especially when it comes to the field of instrumental analysis. The goal of the present thesis was the clarification of crucial analytical and further aspects. The extraction was mostly carried out using the so-called micropulverisation. It rendered the simultaneous milling of the hair matrix and extraction of EtG possible with a high sample throughput. Selection of the analyte and following detection was mainly carried out using HPLC-MS/MS. The quality of analysis was ensured by the successful participation in three interlaboratory tests carried out by the Society of Hair Testing (SoHT). Repetitive conditions were ensured by manufacturing of own hair reference materials as well as by the usage of homogeneous external hair materials. Two hair materials were treated under thermal stress conditions and the EtG values were compared to reference samples to verify the analytes stability. EtG showed extraordinary stability under the chosen conditions. Likewise, an assessment of the degree of EtG decay after oxidative treatment as well as the development of a nondestructive assay via FTIR to detect oxidized cysteine species were established. The model system beard hair was arranged for the conduction of two experimental series: the correlation of the EtG content in beard hair after defined oral consumption of ethanol and the detection of glucuronidation of the corresponding parent substances after consumption. Whilst no distinct correlation could be observed for the ethanol experiment, it was possible to provide evidence for the existence of two glucuronized metabolites of drugs after consumption of the parent compounds.
17

Langzeitnachweis anaboler Steroidhormone

Anielski, Patricia 23 November 2007 (has links)
Die missbräuchliche Anwendung von anabolen Substanzen erfolgt mit dem Ziel eines verstärkten Muskelaufbaus - im Sport zur Leistungsverbesserung, in der Tierzucht zum Erreichen von Zuchtidealen oder bei der Masttierhaltung zur Produktivitätssteigerung. Bisher wurden Doping- oder Medikationskontrollen zum Nachweis von anabolen Steroidhormonen üblicherweise im Urin bzw. im Blut durchgeführt. Für bestimmte Fragestellungen kann der analysierbare Zeitraum allerdings unzureichend sein oder aber die Untersuchungsmaterialien sind unter praktischen Gegebenheiten nur eingeschränkt verfügbar. Das Sammeln von Urinproben ist beispielsweise bei Zuchthengsten nur mit einem unverhältnismäßig hohen Aufwand realisierbar. Haare stellen in solchen Situationen eine Alternative dar, da sich das Entnahmeverfahren unkompliziert gestaltet und bei einer entsprechenden Haarlänge die eingelagerten Fremdstoffe länger als in Urin- oder Blutproben detektierbar sein sollten. In der vorliegenden Arbeit wurde ein effektiver Langzeitnachweis für insgesamt 11 anabole Substanzen in Pferdehaar-Proben mittels GC-HRMS und GC-MS/MS entwickelt (Nachweisgrenzen zwischen 0,1 und 5,0 pg/mg). Dabei können zum einen körperfremde anabole Wirkstoffe (z. B. Steroidester in Depotpräparaten) und zum anderen körper-eigene Steroide analysiert werden (z. B. Testosteron und Nandrolon beim Hengst). In verschiedenen Applikationsversuchen wurde gezeigt, dass durch eine Haaranalyse der Nachweis bis zu einem Jahr möglich ist. Für die endogene Nandrolonmenge in Schweifproben von unbehandelten Hengsten wurde eine signifikante Altersabhängigkeit festgestellt. Die ermittelten physiologischen Höchstkonzentrationen für Nandrolon betragen zwischen 1,1 pg/mg bei Junghengsten (1-3 Jahre) und 3,1 pg/mg bei Althengsten (11-20 Jahre). Die Bestimmung von Nandrolon in Haarproben erwies sich für die Körungskontrollen bei Junghengsten als ein geeignetes Verfahren zur Detektion einer exogenen Zufuhr. Die Untersuchung von Haaren ist zum Langzeitnachweis als Alternative gegenüber Blut- und Urinanalysen vorzuziehen, auch wenn sich retrospektiv nicht alle Fragen zum Behandlungsablauf präzise klären lassen (z. B. Angaben zur Dosierung oder zum genauen Applikationszeitpunkt). Das neu etablierte Verfahren ist außerdem die Methode der Wahl, wenn die Verfügbarkeit der übrigen Probematerialien eingeschränkt bzw. eine einfache und schnelle Beprobung erforderlich ist. Es wird bereits zur Medikationskontrolle bei Zuchthengsten sowie bei speziellen forensischen Untersuchungen eingesetzt.
18

Multi-flex neo-hybrid identities : liberatory postmodern and (post) colonial narratives of South African women's hair and the media construction of identity

Le Roux, Janell Marion January 2020 (has links)
Thesis (Ph.D. Communication Studies)) -- University of Limpopo, 2020 / Hair has been a marker of identity that communicates issues of race, acceptability, class and beauty. Evidence of this was during colonialism and apartheid where South African identities were defined by physical characteristics such as the texture of one’s hair, and the colour of one’s skin. Whiteness was the epitome of beauty which came with certain privileges. Non-White bodies were defined as part of a particular narrative that saw them as well as their hair as inferior to that of White bodies. Academic literature continues to engage African hair from the perspective of a colonial legacy through a postcolonial lens. This study, however, asserts a shift in engaging African hair and introduces an African identity which is re-empowered and liberated through agency and choice, and active participation in the construction of its own identity. This shift in engagement also relinquishes the African identity’s association with the dominant narrative of its conformity to a single European ideology of beauty and identity by introducing a (post)colonial, postmodern theory of a Multi-flex, Neo-hybrid identity which forms part of the theoretical framework of this study. This study draws on the theoretical positions of postmodern theory about the concepts of ‘self’ and identity. It engages interpretations of postmodernism and ‘self’ through the works of Kenneth Gergen and Robert Lifton who provide critical theoretical insight into postmodernism and identity. It also engages critical scholars such as Homi Bhabha, Franz Fanon, Kwame Appiah, Charles Ngwenya and Achille Mbembe, amongst others. Through this theoretical lens, I examine the role of the media in the presentation of the panoply of hair (styles) to South African women in the process of constructing a fluid, flexible and hybrid identity that decentres the ideology of rigid racial identity. I also critically investigate whether non-White women who lived during the colonial-apartheid era and those born in a free democratic era share this multi-flex, neo-hybrid identity of the postmodern woman. Thus this study aims to critically explore social narratives of South African women’s hair and how the media perpetuate the construction of a new postmodern African female identity within the backdrop of the commodification of hair and identity in a globalised market and media environment. Coupled with an interpretivist paradigm, a phenomenological v approach was adopted for this study. Data was collected from print media content material namely, DRUM Hair magazine (editions 2014-2019) due to the assortment of hairstyles and identities it provides for African women. Data was also collected in the form of semi-structured interviews/personal accounts/stories presented as phenomenological narratives from colonial-born Coloured and colonial-born Black female participants. Focus group interviews were conducted on post-apartheid/born-free Coloured and Black female South African participants to understand how these women construct their identities through hairstyle choices and the impact this has on the (re)presentation of their identities within the global beauty market environment. These diverse participants aged from 18 to 104 allow me to trace, if any, the changes in perception of hair and hairstyles from colonial-apartheid South Africa to the new and free post-apartheid South Africa. The results of the study show that media enable the African woman to construct a postmodern identity through the multiplicity of hairstyles/identities available to her. It also provides the African woman with the tools to create various identities for herself through the diversity of hairstyles available to her. The African woman who is exposed to an assortment of hairstyles can navigate from one identity to the next without being loyal to one identity which is typical of the postmodern self. Another finding is that coloniality seems to continue to shape the identities of women born during the colonial apartheid era. But for those born during the (post)colonial and post-apartheid era, they embrace a navigatory form of hybridity that is not loyal to one identity but explores various forms of identity, which the market place affords them and the media perpetuate in the construction of multi-flex, neo-hybrid and postmodern identities. The implication of this study is that it is liberating since it allows us to critically review our identity and what we deem as beautiful and to question the daily choices we make not only with our hairstyles but with fashion, food and other cultural elements that shape our performance of identities. / National Institute for the Humanities and Social Sciences (NIHSS) and South African Humanities Deans Association (SAHUDA)
19

[pt] DESENVOLVIMENTO DE MÉTODO PARA DETERMINAÇÃO DE ENXOFRE EM CABELO POR ESPECTROMETRIA DE ABSORÇÃO MOLECULAR DE ALTA RESOLUÇÃO COM FONTE CONTÍNUA E FORNO DE GRAFITE / [en] DEVELOPMENT OF METHOD FOR DETERMINATION OF SULFUR IN HAIR BY HIGH-RESOLUTION CONTINUUM SOURCE MOLECULAR ABSORPTION SPECTROMETRY AND GRAPHITE FURNACE

VITOR CORNAQUI PEREIRA MARROCOS 09 February 2021 (has links)
[pt] No presente trabalho é proposto o desenvolvimento de um método analítico para determinação de S por espectrometria de absorção molecular de alta resolução com fonte contínua e forno de grafite (HR-CS GF MAS). As amostras foram preparadas por dissolução ácida e os padrões de calibração, assemelhados à matriz da amostra dissolvida, contendo sulfato, tioureia ou L-cisteína foram estudados em função de suas diferentes estabilidades térmicas. A técnica de HR-CS GF MAS é uma alternativa interessante para determinação de S, pois apresenta alta resolução espectral que minimiza interferências espectrais, pelo uso de um monocromador de alta resolução que permite a separação das linhas de absorção molecular do analito e da matriz, pelo uso do forno de grafite como fonte de atomização, que permite a separação da matriz e do analito antes da etapa de medida do sinal analítico. Com isso, este trabalho tem por objetivo desenvolver um método analítico para determinação de S em amostras de cabelo por HR-CS GF MAS, a fim de avaliar os níveis deste elemento no organismo e compará-los com os resultados obtidos por ICP OES. As condições escolhidas para temperatura de pirólise e de vaporização foram 1000 graus C e 2400 graus C, respectivamente, utilizando 800 microgramas de W, como modificador permanente, e 15 microgramas e 10 microgramas, respectivamente, de uma mistura de Pd(mais)Mg, como modificador em solução. O valor determinado para a concentração de S no material certificado de referência NCS DC73347a (cabelo humano) está de acordo com o descrito em seu certificado, bem como as concentrações de S determinadas em 14 amostras de cabelo, que estão em concordância com as determinadas por ICP-OES de acordo com teste t-pareado (95 por cento de confiança), o que comprova a boa exatidão do método proposto. / [en] In the presented work it is proposed the development of an analytical method for sulfur determination by high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). The samples were prepared by acid dissolution and the calibration standards containing sulfate, thiourea, L-cysteine were studied as a function of their different thermal stabilities and its capability for matrix matching. The HR-CS GF MAS technique is an interesting alternative for sulfur determination, since its capability to perform an interference-free analysis due to its high resolution monochromator that allows to overcome the spectral overlapping and by the use of the graphite furnace as atomizer which minimizes the matrix effects before the analytical measurement. The aim of this work is to develop an analytical method for sulfur determination in hair samples by HR-CS GF MAS, in order to evaluate the levels of this element in the human body and to compare them with the results obtained by ICP OES. The chosen conditions for pyrolysis and vaporization temperatures were 1000 C degrees and 2400 C degrees, respectively, using 800 micrograms of W as permanent modifier combined with 15 micrograms and 10 micrograms, respectively, of Pd(plus)Mg mixture as modifier in solution. The value determined for S concentration in the certified reference material NSC DC73347a (human hair) was in agreement with those reported in its certificate, as well as sulfur concentrations determined in 14 hair samples, which are in agreement with those determined by ICP-OES according to the t-paired test (95 percent level of confidence), which proves the good accuracy of the proposed method.
20

Fettsäureethylester als Marker exzessiven Alkoholkonsums

Auwärter, Volker 27 February 2006 (has links)
In der vorliegenden Arbeit wurde ein analytisches Verfahren zur quantitativen Bestimmung von Fettsäureethylestern (FSEE) im Haar und in Hautoberflächenlipiden mittels Headspace-Festphasenmikroextraktion (HS-SPME) und Gaschromatographie-Massenspektrometrie (GC-MS) sowie eine auf Hochleistungs-Flüssigchromatographie mit Photodiodenarray-Detektion (HPLC-DAD) basierende Methode zur Bestimmung der Squalenkonzentrationen in Lipidextrakten entwickelt. Die bei Untersuchung von Proben verschiedener Konsumentengruppen erhaltenen Konzentrationswerte wurden hinsichtlich ihrer Eignung als Marker für chronisch exzessiven Alkoholkonsum untersucht. Aus den Ergebnissen lässt sich schließen, dass Fettsäureethylester im Haar als Alkoholmarker den bisher üblicherweise genutzten Markern wie GGT, CDT oder MCV bezüglich Sensitivität und Spezifität mindestens ebenbürtig sind. Es wurden die folgenden vorläufige Cut-off-Werte festgelegt: wenn sich im Haar für die Summenkonzentration der vier in der höchsten Konzentration vorkommenden FSEE (Ethylmyristat, Ethylpalmitat, Ethyloleat und Ethylstearat) ein Wert > 1 ng/mg ergibt, kann mit hoher Sicherheit von chronisch exzessivem Alkoholkonsum ausgegangen werden, für Abstinenzler werden typischerweise Werte < 0,4 ng/mg gefunden. Durch Bildung des Quotienten der FSEE-Konzentrationen und der Squalenkonzentrationen wurden relative FSEE-Konzentrationen erhalten, die im Falle der Haaranalyse zu einer Verbesserung der Zuordnungssicherheit zu den entsprechenden Konsumentengruppen führten bzw. bei der Analyse von Hautoberflächenlipiden einen sinnvollen Vergleich der Werte erst ermöglichten. Als vorläufiger Cut-off-Wert für die relativen FSEE-Konzentrationen wurde ein Wert von 2 ng/µg vorgeschlagen. Als weiteres wichtiges Ergebnis der Arbeit wurde der Einlagerungsmechanismus der FSEE ins Haar aufgeklärt. Es konnte gezeigt werden, dass Fettsäureethylester in erster Linie über das Sebum ins Haar gelangen. / The current doctoral thesis presents the development of an analytical procedure for the quantitative analysis of fatty acid ethyl esters (FAEE) in hair and in skin surface lipids using headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) as well as a method based on high-performance liquid chromatography with photodiode array detection (HPLC-DAD) to determine squalene concentrations in lipid extracts. The results obtained from analysis of samples from different alcohol consuming groups showed that FAEE are suitable markers for long-term alcohol misuse. Concerning sensitivity and specifity they are at least as good as other commonly used markers like GGT, CDT or MCV. The following provisional cut-off values were established: for chronically excessive alcohol consumption, the sum of the four FAEE (ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate) found in the highest mean concentrations should be > 1 ng/mg in hair; for non-drinkers, concentrations < 0,4 ng/mg are typical. The quotient obtained by dividing the FAEE concentration by the squalene concentration was defined as the relative FAEE concentration, which provides a better classification of the samples regarding the consumer groups through hair analysis. Relative FAEE values also allow a reasonable comparison in the case of skin surface lipid concentrations for the first time. 2 ng/µg is suggested as a preliminary cut-off value. As a further important result of the current work, the mechanism of incorporation of FAEE into hair was clarified. It was shown that fatty acid ethyl esters are incorporated into hair mainly through sebum.

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