Part 1: The emergence of environmentally friendly commercial products and their impact on fire debris analysis. Environmentally friendly products (i.e. green products) are environmentally preferable choices relative to comparable commercial products. They are readily available to the public, often highly flammable, and can be used by criminals as accelerants to facilitate the start and/or spread of fire. It is critical for analysts to have an understanding of their composition and chromatographic characteristics. Green products include paint thinners, solvents, removers, and cleaning and surface preparation products. As the composition of commercial products continually change over time, the fire debris community needs to be aware of the variety of environmentally friendly ignitable liquids that could be encountered during casework. Traditionally, when fire debris analysts have been trained, they are taught that most of the ignitable liquid residues they will encounter in casework are petroleum-based products. With the increasing emergence of non-petroleum based green products in the consumer marketplace, such products may be encountered more often than ever before in fire debris evidence submitted to forensic laboratories. Analysts should become familiar with the chromatographic features of these products as neat liquids as well as when present in fire debris samples. The purpose of this study is to introduce fire debris analysts to the prevalence of green products and increase knowledge regarding a variety of green product compositions and the characteristics they exhibit when analyzed as neat liquids and in "mock" fire debris samples. Several green products were analyzed as neat liquid samples and subsequently extracted from fire debris samples using typical fire debris extraction and analysis techniques in order to familiarize fire debris analysts with the chromatographic and mass spectral features of these products. General information about different types of green commercial products, their chromatographic and mass spectral characteristics, and their interpretation will be summarized. Analytical methods were developed for the analysis of environmentally friendly products and included considerations of gas chromatography oven temperature and ramp rate, hold times, and flow rate, as well as the scan rate and range of the mass spectrometer. Analyses involving common substrates were performed, including spiking green products onto various substrates with subsequent analysis and comparison of burned and unburned samples. Part 2: Application of fast GC/MS analysis for the identification of ignitable liquids in fire debris samples. Fire debris samples that contain ignitable liquid residues undergo a two-step process of extraction, most commonly via passive adsorption elution (PAE) onto an activated carbon strip, and instrumental analysis by gas chromatography/mass spectrometry. Upon completion of PAE, adsorbed compounds are eluted from the adsorbent with a suitable solvent and analyzed using (GC/MS) for the potential identification of ignitable liquid residues. A thorough evaluation of the literature revealed the average run time for gas chromatography of fire debris samples that contain hydrocarbon or petroleum based ignitable liquids to be 30 minutes. Additionally, a blank sample is run before an evidentiary sample to ensure solvent purity and to ensure any chromatographic carry over has not occurred between subsequent injections. The average run time, along with case volume, extraction times and case reviews contributes significantly to the backlog of samples to be analyzed in most crime laboratories around the country. Fast-GC/MS would significantly reduce analysis time, lower operating costs and would use less consumables. Based on a process known as pattern recognition, an initial goal of a fire debris analyst is to identify a pattern that is consistent with an ignitable liquid class. The standard method followed by most fire debris analysts use or base standard operating procedures (SOPs) on the American Society of Testing and Materials (ASTM) E1618, which defines the classes of commercial ignitable liquids based on chemical composition and boiling point range (or volatility). This study was conducted to optimize current methods of ignitable liquid detection and to optimize fast-GC/MS conditions for the identification of ignitable liquids in fire debris samples. Additionally, this study was conducted to determine if fast-GC/MS can reduce chromatographic separation times without sacrificing peak resolution and subsequently allow for ignitable liquid discrimination. Method development included considerations of flow rate, initial GC oven temperature, ramp rate, and mid and end temperature hold times. Fast-GC/MS conditions were tested on neat ignitable liquids from all nine ASTM E1618 classes. Optimizing fast-GC/MS method parameters led to an increase in sample throughput in comparison to traditional GC/MS methods. As a result, the GC/MS identification of ignitable liquids and their residues was performed in a quarter of the amount of time when compared to traditional methods.

The objective of this study was to determine the capability and applicability of a conventional gas chromatography system for fast chromatography. Many gas chromatographic separations actually require much Iss time than js actually being spent on the analysis. Capillary columns are known to be very efficient due to the long lengths and thin stationary phase films. However, analysis can be done much faster if shorter column lengths and thinner stationary phases are used because the retention time is a function of the column length and stationary phase film thickness. This study involves varying a number of column and instrumental parameters in order to determine their effect on the chromatographic analysis time. The parameters which were varied include the column stationary phase film thickness, the column length, the injection volume, the split ratio, the column position, the injector liner, and the flow and temperature programming rates. The effect of column length on the average linear gas velocity was also determined by plotting the Golay equation for each. The Golay equation (12) illustrates the effect of the various column parameters on column efficiency. The most detrimental effect of decreasing the analysis time is the loss of resolution that may occur. Both shorter lengths and faster than optimum flow rates result in lower resolution. By careful adjustment of some column parameters, the loss in resolution can be minimized. The results of this research show that many gas chromatographic analyses require much less time than is actually spent and that a fast analysis can be achieved with little to no loss in resolution. / Master of Science

Made available in DSpace on 2014-07-29T15:11:10Z (GMT). No. of bitstreams: 1 Tese Rodrigo I Medeiros.pdf: 2094204 bytes, checksum: 5d1ccae92a1ff1a8355428a531e6a4b9 (MD5) Previous issue date: 2011-03-18 / An analytical chemical method for the forensic analysis of an illicit drug merla, whose the main constituent is the cocaine was development. Thermogravimetric analysis admitted to understand the thermal behavior of samples and quantifying the stages of mass loss, which together with the quantification endothermic event in DSC, the results were essential for the generation of analytical answers used to construct the data matrix of the statistical analysis. An efficient process for the precipitation of inorganic substances was established, which simultaneously allowed the extraction of two liquid fractions, organic and aqueous, being determinate a partition coefficient of 96,22 % for cocaine, using ethyl acetate as solvent, which showed lower elution time (0.58 min.) among the solvents evaluated. A method by Fast GC for cocaine analysis was developed, reducing the analysis time of 14.5 to 4.5 min was developed, which allowed analyze merla sample and the normalization of the chromatographic peaks of cocaine, demonstrated the great variation of its concentration in merla. Noticed of the potential of the method involving the thermo-analytical and chromatographys techniques to generate experimental results obtained statistically enabled a classification and grouping of samples by Euclidean Distance by the Hierarchical Cluster Analysis (HCA), estimated whether seized samples with different users were manipulated in the same laboratory and if determined city has separate laboratories for illegal preparatiom of drug narcotic. / Neste estudo realizou-se o desenvolvimento de um método químico analítico forense para a análise de uma droga ilícita a base de cocaína, a merla. As análises termogravimétricas permitiram conhecer o comportamento térmico das amostras e quantificar as etapas de perdas de massa, que juntamente com a quantificação de evento endotérmico em DSC, foram essenciais para a geração de resultados analíticos utilizados na construção da matriz de dados do tratamento estatístico. Foi estabelecido um processo eficiente para a precipitação das substâncias inorgânicas, que simultaneamente permitiu a extração de duas frações líquidas, orgânica e aquosa, sendo determinado um coeficiente de partição de 96,22 % para a cocaína, tendo como solvente acetato de etila, o qual apresentou menor tempo de eluição (0,58 min.) dentre os solventes avaliados. Foi desenvolvido um método Fast GC para análise de cocaína, diminuindo o tempo de análise de 14,5 min para cerca de 4,5 min, o qual permitiu analisar as amostras de merla e, pela normalização dos picos cromatográficos da cocaína, perceber a grande variação de sua concentração na merla. Observou-se o potencial do método envolvendo as técnicas termoanalíticas e cromatográficas para geração de resultados experimentais que tratados estatisticamente possibilitaram a classificação e o agrupamento das amostras pela distância euclidiana obtida por Análise Hierárquica de Agrupamentos (HCA), avaliando se amostras apreendidas com diferentes usuários foram manipuladas em um mesmo laboratório e se determinada cidade possui laboratórios distintos de preparo ilegal de tóxico-entorpecente.

Experimental data are presented for the first time in support of a theoretical model of band broadening proposed by Blumberg (1997). This model addresses the effects of the compressibility of the mobile phase in gas chromatography and presents an equation derived from only two mutually independent variables. Solutions of decane and tridecane in hexane were analyzed at pressures ranging from 15 to 150 psi. Six different columns were used that varied in length, internal diameter and film thickness. Theoretical plate heights were obtained from this data and plotted versus the average linear carrier gas velocity (Golay type plots). These plots showed that at high pressures the Blumberg model fit the experimental data statistically significantly better than the earlier model proposed by Golay. The Blumberg model also accurately predicts the relationship between the optimum linear carrier gas velocity and the temperature. The second part of this work explores the scope and limitations of fast temperature programming in the fast GC analyses of various sample types. These samples included polycyclic aromatic hydrocarbons (PAHs), hydrocarbons and food samples. Programming rates of up to 1200° C/min were used. These fast programming rates were obtained by using "flash"â ¢ temperature programming, controlled by resistive heating of a metal tube that enclosed a capillary column. The precision of peak data was found to be good, less than 5% for peak areas and 4% for retention times. However, a slight, but statistically significant decrease in peak areas was seen above programming rates of 240° C/min. Microwave assisted extraction (MAE) was used to extract 2,6-di-(tert-butyl)-4-methylphenol, BHT, from chewing gum and breakfast cereal. The extraction was followed by a fast GC analysis (less than 4 minutes) using "flash"â ¢ temperature programming. MAE reduced the sample preparation time, from hours to minutes, and consequently reduced, the total analysis time. Extraction times longer than 5 minutes gave decreased recoveries of BHT. / Ph. D.

English: Semiochemicals informative molecules used in insect-insect or plant-insect interactions have been widely considered within various integrated pest management (IPM) strategies. In the present thesis, two sesquiterpenoids, E-β-farnesene and E-β-caryophyllene, were formulated for their related properties as aphid enemy attractants. E-β-farnesene, the alarm pheromone of many aphid species, was also identified as a kairomone by attracting and inducing oviposition of aphid predators (Episyrphus balteatus De Geer (Diptera: Syrphidae)) and by attracting aphid parasitoids (Aphidius ervi Haliday (Hymenoptera: Braconidae)). E-β-caryophyllene was identified as a potential component of the aggregation pheromone of the Asian ladybird, Harmonia axyridis Pallas, another aphid predator. The two products were purified from essential oils of Matricaria chamomilla L. (Asteraceae) and Nepeta cataria L. (Lamiaceae) for E-β-farnesene and E-β-caryophyllene, respectively. Natural and biodegradable slow-release formulations were then investigated in order to deliver these molecules on crop fields for a long period of time as biological control devices. Due to their sensitivity to oxidation, both sesquiterpenes needed to be protected from oxygen degradation. For this purpose, alginate hydrophilic matrix with low oxygen permeability was used as polymer for the formulations: the main objective was to deliver semiochemical substances in the air in a controlled way. Consequently, a careful selection of alginates was realised. Formulated beads showed different structural and encapsulation properties depending on various formulation factors. Alginate formulations were characterized by texturometry and by confocal microscopy in order to observe the distribution of semiochemicals in alginate network. The last step of alginate bead characterisation consisted in studying release rate of semiochemicals in laboratory-controlled conditions by optimised trapping and validated Fast-GC procedures. Finally, the efficiency of formulations as aphid predator (Syrphidae) and parasitoids (A. ervi) attractants was demonstrated by field trapping and olfactometry experiments. Français: Les sémiochimiques molécules véhiculant des informations au sein des interactions insecte-insecte ou plante-insecte ont été largement utilisés dans de nombreuses stratégies de lutte intégrée. La présente thèse de doctorat décrit la formulation de deux sesquiterpènes, le E-β-farnésène et le E-β-caryophyllène, pour leurs propriétés relatées dans la littérature en tant quattractants des ennemis des pucerons. En effet, le E-β-farnésène, la phéromone dalarme de nombreuses espèces de pucerons, a également été identifié comme kairomone en attirant des parasitoïdes (Aphidius ervi Haliday (Hymenoptera: Braconidae)) et des prédateurs de pucerons (Episyrphus balteatus De Geer (Diptera: Syrphidae)) et en induisant un comportement doviposition chez ces derniers. Le E-β-caryophyllène a récemment été identifié comme un composé probable de la phéromone dagrégation des coccinelles asiatiques, Harmonia axyridis Pallas, également prédatrices de pucerons. Les deux produits ont été purifiés au départ des huiles essentielles de Matricaria chamomilla L. (Asteraceae) et de Nepeta cataria L. (Lamiaceae) respectivement dans le cas du E-β-farnésène et du E-β-caryophyllène. Des formulations biodégradables et dorigine naturelle ont ensuite été développées comme outil de contrôle biologique afin de libérer les deux composés de façon progressive. En raison de leur sensibilité à loxydation, ces deux sesquiterpènes devaient être protégés de loxygène. A cette fin, de lalginate matrice hydrophile offrant une faible perméabilité à loxygène a été utilisé comme polymère de formulation : le principal objectif était de délivrer les substances sémiochimiques dans lair dune façon contrôlée. En conséquence, lalginate a été sélectionné de façon minutieuse. Les billes formulées ont montrés des propriétés structurelles et dencapsulation différentes en fonction de nombreux facteurs intervenant lors de la formulation. Les formulations ont été caractérisées par texturométrie et par microscopie confocale de façon à observer la distribution des sémiochimiques au sein du réseau dalginate. La dernière étape de caractérisation des billes a consisté en létude du taux de libération des sémiochimiques dans des conditions contrôlées de laboratoire après avoir optimisé la technique de piégeage des volatils et validé la procédure danalyse par GC rapide. Finalement, lefficacité dattraction des formulations envers les prédateurs et les parasitoïdes de pucerons a été démontrée par des expériences de piégeage sur cultures et des essais dolfactométrie.

One of the main problems encountered in chemical analysis operations in the field is collecting sufficient sample from the source and transferring that sample to the measurement instrument for fast separation and identification. I have been involved in developing a field-portable gas chromatography-mass spectrometry (GC-MS) system with solid phase microextraction (SPME) sampling for point detection of chemical agents. The objective is to minimize the analysis time between sampling and detection of a potential chemical threat. SPME offers a convenient means for sampling gaseous and liquid samples, concentrating the analytes, and transferring the analytes to the injection port of a GC system for separation and identification. GC-MS has advantages of high efficiency, speed, and applicability for field analysis. Work was done to optimize the SPME fiber coating, capillary column dimensions, and GC operating conditions to provide complete analysis within 3 minutes. Since isothermal operation of the GC was a prior requirement, many components in the chromatograms were unresolved. Therefore, a peak de-convolution algorithm was applied to allow for identification and quantitation of poorly resolved and often completely obscured trace components. Details of the instrumentation and optimization of operating conditions are described in this thesis.