The current methods for identifying ignitable liquid residues in fire debris are heavily based on the holistic, qualitative interpretation of chromatographic patterns with the mass spectral identification of selected peaks. The identification of neat, unweathered ignitable liquids according to ASTM 1618 using these methods is relatively straightforward for the trained analyst. The challenges in fire debris analysis arise with phenomena such as evaporation, substrate interference, and biodegradation. These phenomena result in alterations of chromatographic patterns which can lead to misclassifications or false negatives. The biodegradation of ignitable liquids is generally known to be more complex than evaporation [20], and proceeds in a manner that is dependent on numerous factors such as: composition of the petroleum product/ignitable liquid, structure of the hydrocarbon compound, soil type, bacterial community, the type of microbial metabolism that is occurring, and the environmental conditions surrounding in the sample. While nothing can be done to prevent the biodegradation, continued research on biodegraded ignitable liquids and the characterization of the trends observed may be able to provide insight into how an analyst can identify a biodegraded ignitable liquid residue. This research utilized normalized abundance values of select ions from pre-existing gas chromatography-mass spectrometry (GC-MS) data on samples from three different gasoline and diesel biodegradation studies. A total of 18 ions were selected to indicate the presence of six hydrocarbon classes (three each for alkanes, aromatics, cycloalkanes, naphthalenes, indanes, and adamantanes) based on them being either base peaks or high abundance peaks within the electron impact mass spectra of compounds within that hydrocarbon class. The loss of ion abundance over the degradation periods was assessed by creating scatter plots and performing simple linear regression analyses. Coefficient of determination values, the standard error of the estimate, the slope, and the slope error of the best fit line were assessed to draw conclusions regarding which classes exhibited desirable characteristics, relative to the other classes, such as a linear degradation, low variation in abundance within the sampling days, and a slow rate of abundance loss over the degradation period. Additional analyses included two-way analysis of the variance (ANOVA), to assess the effects of time as well as different soil type on the degradation of the hydrocarbons, stepwise multinomial logistic regressions to identify which classes were the best predictors of the type of ignitable liquid, and one-way ANOVAs to determine where the differences in the ratios of hydrocarbon classes existed within each of the ignitable liquids, as well as between the two liquids. Hydrocarbon classes identified as exhibiting characteristics such as slow and/or reliable rates of abundance loss during biodegradation are thought of as desirable for future validation studies, where specific ranges of hydrocarbon class abundance(s) may be used to identify the presence of a biodegraded ignitable liquid. Classes of hydrocarbons that have experienced biodegradation that maintain an abundance close to that of a neat, non degraded counterpart, or that reliably degrade and have predictable abundance levels given a particular period of degradation, would be instrumental in determining whether or not an unknown sample contains an ignitable liquid residue. It is the hope that these assessments will not only provide helpful information to future researchers in the field of fire debris analysis, but that they will create interest in the quantitative, statistical assessment of ignitable liquid data for detection and identification purposes.

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 production of methamphetamine in clandestine laboratories presents a particular hazard due to the environmental hazards it poses. In addition to the dangers associated with using caustic and reactive solvents, these clandestine laboratories also have to potential to cause a fire or explosion. This danger has caused some states to redefine arson to include fires caused by the illicit manufacture of drugs. Arson investigation can be challenging due to the destructive nature of the crime. Much of the evidence that existed prior the fire can be consumed and evidence that does survive can be difficult to identify in the rubble. Despite these difficulties, methods have been developed to determine the types of accelerants present in addition to identifying illicit substances such as methamphetamine and the precursor drug pseudoephedrine. This study was designed to determine if solid phase microextraction combined with gas chromatography/mass spectrometry could be used to analyze burned samples of wood to which pseudoephedrine had been applied. In addition, an experiment was designed to determine what concentration of pseudoephedrine must be present before a fire in a controlled laboratory setting, for a detectable amount to remain. Samples were created by adding pseudoephedrine hydrochloride, either in powder form or dissolved in methanol, to blocks of Douglas Fir and exposing the surface to a flame for two minutes. Additional samples were created by adding trace amounts, i.e. microliter quantities, of pseudoephedrine standard to blocks of wood before placing them in a fire for ten minutes. A thermal degradation product of pseudoephedrine was detected in samples containing more than 15 mg of the drug. To verify that the detected product was a result of thermal degradation, 10 mg of pseudoephedrine were heated at 200 °C for one hour. The product of the thermal degradation study and the product detected following two minutes of exposure to a flame had the same retention time and mass spectrum. Therefore, it was concluded that the detected thermal degradation product may be used to indicate the presence of pseudoephedrine in a fire.

Identification of ignitable liquids in fire debris analysis using pattern recognition is an important step in determining the nature of a suspicious fire. Complex mixtures that make up ignitable liquids are susceptible to microbial degradation when fire debris evidence is presented in the form of soil. Microbial degradation results in a selective metabolism of certain classes of compounds required for identification of an ignitable liquid. Various ignitable liquids that may be used to initiate or propagate a fire contain different classes of organic compounds. These include normal alkanes, branched alkanes, cycloalkanes, aromatics, terpenes, and others. In this work, microbial degradation of nine ignitable liquids in soil was evaluated over a period of twenty-six days. The degradation of aromatic compounds in gasoline was faster with toluene and C2-alkylbenzenes than in C3-alkylbenzenes. However, the overall loss of aromatics made gasoline chromatographically unidentifiable. The complete loss of n-alkanes in medium and petroleum distillates resulted in patterns that resembled naphthenic-paraffinic products. Normal alkanes were more susceptible to microbial degradation than isoalkanes, which was specifically demonstrated in medium and heavy petroleum distillates. In diesel, pristane and phytane remained prominent in comparison to the normally prevalent n-alkanes, which could no longer be detected post-degradation. The degradation of isoalkanes and cycloalkanes was evaluated in a naphthenic-paraffinic product. Isoalkanes were degraded significantly faster than cycloalkanes. The remaining peaks in the naphthenic-paraffinic pattern consisted solely of cycloalkane compounds, and could no longer be classified as a naphthenic-paraffinic product. The terpene compounds in turpentine were also observed to be susceptible to degradation by microorganisms. The loss of !-pinene, limonene, and camphene was significantly noticeable in comparison to other terpene compounds, such as 1,4-cineole. Microbial biodegradation in different soil types was investigated. The difference in soil texture can affect the rate of metabolism of ignitable liquids due to the variance of available oxygen, nutrients and mobility of the microbial population. The degradation of isoalkanes, cycloalkanes, aromatics and heavier normal alkanes was faster in clay, whereas normal alkanes of lower molecular weight were degraded more readily in sand. There has been no explanation of this occurrence within the scientific literature, however it could be hypothesized that the difference in microbial flora and water saturation levels could affect the selective degradation between the two soil types. Fire debris evidence is often stored for long periods of time before analysis due to case backlogs. The storage condition of arson-related soil samples is a sensitive subject. If evidence, containing soil, is stored at room temperature, petroleum compounds in any ignitable liquid residues that are present will be degraded within a week. Therefore, it is important to freeze or refrigerate soil samples. The storage of both refrigerated and frozen soil samples containing gasoline were evaluated over six months. Less than 6% of the aromatic compounds distinctive of gasoline remained when stored at 5 °C, while minimal change was observed in the same compounds when stored at -15 °C. Microbial degradation of petroleum-based ignitable liquids is advantageous from the environmental perspective. However, within the forensic community the effect of microbial action could lead to misclassification or inability to identify the presence of an ignitable liquid in fire debris evidence.

Fire incidents are a major contributor to the number of deaths and property losses within the United States each year. Fire investigations determine the cause of the fire resulting in an assignment of responsibility. Current methods of fire debris analysis are reviewed including the preservation, extraction, detection and characterization of ignitable liquids from fire debris. Leak rates were calculated for the three most common types of fire debris evidence containers. The consequences of leaking containers on the recovery and characterization of ignitable liquids were demonstrated. The interactions of hydrocarbons with activated carbon during the extraction of ignitable liquids from the fire debris were studied. An estimation of available adsorption sites on the activated carbon surface area was calculated based on the number of moles of each hydrocarbon onto the activated carbon. Upon saturation of the surface area, hydrocarbons with weaker interactions with the activated carbon were displaced by more strongly interacting hydrocarbons thus resulting in distortion of the chromatographic profiles used in the interpretation of the GC/MS data. The incorporation of an additional sub-sampling step in the separation of ignitable liquids by passive headspace sampling reduces the concentration of ignitable liquid accessible for adsorption on the activated carbon thus avoiding saturation of the activated carbon. A statistical method of covariance mapping with a coincident measurement to compare GC/MS data sets of two ignitable liquids was able to distinguish ignitable liquids of different classes, sub-classes and states of evaporation. In addition, the method was able to distinguish 10 gasoline samples as having originated from different sources with a known statistical certainty. In a blind test, an unknown gasoline sample was correctly identified from the set of 10 gasoline samples without making a Type II error.

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.

In fire debris analysis, substrate contribution refers to compounds present within the material collected that can interfere with the instrumental detection of ignitable liquids or contribute petroleum or alcohol-based compounds, which may complicate the interpretation. The concept of substrate contribution was brought to light by "The petroleum-laced background" by Lentini et al. focusing on commercial products (e.g. tennis shoes, magazines, etc.), the publication successfully illustrated that these products can produce chromatograms similar to those generated by the presence of petroleum-based ignitable liquids (ILs). As a result, Lentini et al. demonstrated that fire debris analysts can identify the presence of ignitable liquids without realizing the compounds in question might be the result of the manufacturing processes, and are inherent to the substrate in question. Therefore, the findings may or may not be probative. Gasoline is easily accessible and is frequently used by arsonists. As such, fire debris analysis focuses primarily on petroleum-based compounds. However, oxygenated solvents, which encompass all oxygen-containing compounds as defined by the American Society for Testing and Materials (ASTM) classification scheme, can also be used in an arson event. Despite the potential to be used as ILs, little is known regarding the recovery of these compounds. Previous thesis projects from the Biomedical Forensic Sciences program at Boston University School of Medicine explored and optimized the use of zeolites in recovering low molecular weight oxygenated ignitable liquids. An isothermal gas chromatography/mass spectrometry (GC/MS) method was also developed to detect these oxygenated ILs. The results from these projects show that zeolites have the potential to be used in forensic casework. Inspired by previous publications and thesis research, the goal of this project was to first develop a reference library on substrate contribution from oxygenates (e.g. ethanol, isopropanol and acetone) present in commercial products using the isothermal GC/MS methods. The development of this reference library included a specific interest in wood treatment products, considering wood is one of the most commonly submitted fire debris materials. The second stage involved an attempt at evaluating extraction efficiencies of activated charcoal strip and zeolites. The results of this project suggested that automotive and food products examined contained only acetone and ethanol respectively, while the variety of oxygenates found in household and personal care products indicated further analysis of additional products in these categories would be beneficial. Moreover, the results also reaffirmed zeolites' role in recovering oxygenated ILs in a controlled testing environment using KimWipes as a non-contributing substrate. However, the instrumental method required some modifications, as there was partial separation between ethanol and acetone. The results from applying products onto wooden blocks suggested that activated charcoal strips recovered more oxygenates than zeolites. This unexpected result prompted an investigation into the existing extraction parameters. The investigation suggested that the wooden blocks themselves were responsible for the unexpected recovery results, and future studies would be needed to understand if this recovery was substrate-specific.

In this dissertation research, two fundamental studies involving gas chromatography mass spectrometry of n-butylbenzene and pyrolysis products are presented. In the first study, fragmentation pathways of n-butylbenzene in quadrupole ion trap have been investigated. At low energy, product ion corresponding to m/z 92 and m/z 91 are formed via competitive parallel dissociation. Studies have also shown that at higher energy m/z 92 has sufficient internal energy to undergo further fragmentation yielding m/z 91 via consecutive dissociation. Thus in order to discern the fragmentation pathways of n-butylbenzene, the technique of two-dimensional correlation spectroscopy (2DCOS) was applied to the mass spectral data. Application of 2DCOS resulted in two 2D correlation spectra namely synchronous and asynchronous. A third spectra known as coherence spectra was obtained from the ration of asynchronous to synchronous correlation intensities. For the elucidation of n-butylbenzene fragmentation pathways, all the three spectra were utilized in this study. The second study in this dissertation involves investigation of pyrolysis products to aid in fire debris analysis. One of the major concerns in fire debris analysis is that pyrolysis products can mask the patterns of compounds of interest and make the chromatographic results interpretation extremely difficult. One of the approaches for investigating the formation of pyrolysis products is to subject the commonly found building materials to controlled heating in laboratory. In this study, new heating methodologies for controlled heating of substrates involving furnace, paint-cans and flat steel pans have been developed. The substrates used for investigating pyrolysis products were polystyrene, polyvinylchloride, polybutadiene, yellow-pine, nylon carpet and padding. Experiments were also performed to investigate the influence of hydrocarbons on the formation of pyrolysis.

Ignitable liquids consist of either a single organic compound or a complex organic mixture. In regards to fire debris analysis, the analyst is responsible for determining if an ignitable liquid residue is present. However, when extracted from soil-containing fire debris evidence, chemical degradation from microorganisms is observed to result in the loss of compounds based on chemical structure. It can also happen when the evidence container is stored at room temperature before analysis. This can present a challenge to the fire debris analyst when identifying and classifying the ignitable liquid residue based on the criteria established by standard test methods. The purpose of this research was to observe the microbial degradation of fourteen compounds, at room temperature over a period of time, for possible by-product formation that could coincide with compounds normally present in an ignitable liquid. Additionally, a quantitative assessment was performed to observe and record the loss rate of compounds in a representative simple mixture. Finally, the loss rate from the simple mixture was compared to commercially available ignitable liquids. Degradation studies were conducted to observe the microbial degradation of a representative compounds (individually and in a simple mixture, both weathered and unweathered) and seven ignitable liquids of different ASTM E1618 classifications. Potting soil was spiked with 20 µL of a liquid/compound and was allowed to stand at room temperature for a period of time. The simple mixture was evaporated to 50% and 90% using a steady nitrogen gas flow to compare the degradation process to the unweathered mixture. All samples were extracted and analyzed using passive-headspace concentration and gas chromatography-mass spectrometry. The formation of by-products was not observed when degrading the compounds from the simple mixture individually as seen in other research. The simple mixture, unweathered and 50% weathered, resulted in rapid degradation of their oxygenated compounds. The straight-chained alkanes and toluene were observed to be more susceptible to microbial attack than the highly-substituted aromatics and the branched and cyclic alkanes. The 90% weathered mixture followed the same degradation trend as the unweathered and 50% weathered samples, although it only contained two compounds. The loss rates/half-lives for each simple mixture sample (unweathered, 50% weathered, and 90% weathered) were determined to be approximately 3.5, 3.5, and 0.84 days. The unweathered and 50% weathered sample half-lives were similar due to containing compounds with similar susceptibility to degradation, while the 90% weathered sample contained one compound that was more highly susceptible to degradation. When comparing the 3.5 day half-life to the seven different ASTM class liquids, the isoparaffinic product and the naphthenic-paraffinic product had similar rates of degradation while aromatic solvent and normal alkane classes had the shortest half-lives. When observing the degradation of the gasoline, medium petroleum distillate and the miscellaneous, the constituent compounds were seen to exhibit a range of degradation rates that corresponded to half-lives less than and greater than 3.5 days.

It is not uncommon for criminals to start a fire at a crime scene to conceal evidence of the initial crime. The rationale for this can be attributed to the belief that a fire will destroy all physical evidence. It has been shown in previous research that physical evidence in the form of ignitable liquid residues, fingerprints and even DNA (deoxyribonucleic acid) evidence can still be recovered from the scene of a fire. However, testing of fire debris evidence for multiple forms of evidence has no universally accepted protocol or order of testing. The purpose of this study is two-fold. DNA recovered from simulated fire debris evidence exposed to various ignitable liquids and burn conditions was compared to determine under what scene conditions it could be feasible to recover DNA evidence and generate usable profiles. Additionally, DNA recovered from samples subjected to different time and temperature conditions of heated passive headspace concentration (HPHC) were compared to determine if it was advisable to perform HPHC in an attempt to recover volatile ignitable liquid evidence prior to testing for DNA. The HPHC overall had no significant effect on the degradation or recovered quantities of DNA, and, under the conditions tested, this would not preclude testing for ignitable liquids prior to testing for DNA. The presence of ignitable liquids did not affect the ability to recover DNA or result in degraded DNA, while burning samples prevented DNA from being recovered in all but a few samples, primarily semen samples.