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.

Improvised explosive devices (IEDs) continue to be a national threat to the safety and security of the public. Research in explosives analysis for intact and post-blast samples continue to be a topic in which practitioners are constantly improving and searching for faster methods and techniques to analyze these sample types. The key role crime laboratories play in analyzing these sample types can have limitations, such as increasing turnaround times and backlogs. This concern additionally plays a role in the safety of the public if an unknown individual has not been discovered. Current analytical instrumentation in which explosives are analyzed includes Gas Chromatography – Mass Spectrometry (GC-MS), Liquid Chromatography – Mass Spectrometry (LC-MS), and Ion Mobility Spectrometry (IMS). Each instrument has benefits in the analytical results obtained. Direct Analysis in Real Time - Mass Spectrometry (DART-MS) has shown a significant promise as an analytical approach that can help remedy the time an explosive sample is analyzed, while additionally providing discriminating analytical results. Previous research has shown that DART-MS is capable of analyzing explosives, including smokeless powder. A limitation currently in the area of smokeless powder analysis with DART-MS is the application of utilizing this method and technology to realistic casework that may be encountered in forensic laboratories. Intact and post-blast explosive samples encountered in forensic laboratories arrive in various states and conditions. For example, the severity of the blast and environmental factors may play a role in the detection of smokeless powder on these sample types. To provide objective information and additional research, studies were conducted with mixture samples of smokeless powder and potential matrices that may be encountered in real world case samples. Faster processing time, in addition to the discrimination of smokeless powder, was the ultimate goal of this research. Due to the complexity of the mass spectra that may be generated from sample mixtures, an extraction technique coupled with DART-MS was investigated. A liquid-liquid extraction (LLE) method and dynamic headspace concentration using Carbopack™ X coated wire mesh were tested for the effectiveness of separating the analytes of interest of smokeless powder from various matrix interferences. Hodgdon Hornady LEVERevolution (HHL) smokeless powder, Pennzoil 10W-40 (P10W40) motor oil, and residue from metal end caps (China SLK brand) and black steel pipe nipples (Schedule 40) were used during the course of the matrix interference study. The method of applying dynamic headspace concentration using Carbopack™ X coated wire mesh and analysis by DART-MS provides an effective alternative to obtaining mass spectral data in a shorter amount of time, compared to techniques currently used in forensic laboratories. Effective separation was not achieved using the various LLE methods tested. Further testing would be required in order to evaluate the feasibility of implementing the technique as a sample preparation approach prior to analysis by DART-MS.

Improvised explosive devices (IEDs) are charged devices often used by terrorists and criminals to create public panic. When the general public is targeted by an act of terrorism, people who are not injured or killed in the explosion remain in fear until the perpetrator(s) has been apprehended. Methods that can provide investigators and first responders with prompt investigative information are required in such cases. However, information is generally not provided quickly, in part because of time-consuming techniques employed in many forensic laboratories. As a result, case report turnaround time is longer. Direct analysis in real time - mass spectrometry (DART-MS) is a promising analytical technique that can address this challenge in the Forensic Science community by permitting rapid trace analysis of energetic materials. The builder of an IED will often charge the device with materials that are readily available. The most common materials employed in the construction of IEDs are black and smokeless powder. However, other materials may include ammonia- or peroxide-based materials such as common household detergents. Smokeless powder is a propellant that is readily available to civilians. They are typically used for reloading ammunition and are sold in large quantities each year in the United States. Some states have stricter regulations than others but typically a firearms license is all that’s required to possess smokeless powder. Smokeless powder is considered a low explosive which is capable of causing an explosion if a sufficient quantity is deflagrated inside a confined container. The most commonly employed confirmatory techniques for the analysis of smokeless powder are gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). These methods often require extensive and time-consuming sample preparation procedures to prepare the powders for analysis. In addition to lengthy sample preparation procedures, GC-MS and LC-MS often require chromatographic separations that can range anywhere from 5 to 30 minutes or longer per sample. Ion mobility spectrometry (IMS) is widely used for the field analysis of smokeless powder and can provide faster results in comparison to GC-MS or LC-MS. However, identification is limited to drift time and no structural information is provided unless coupled to a mass spectrometer. In an effort to accelerate the speed of collection and characterization of smokeless powder, an analytical approach that utilizes novel wire mesh coated with CarbopackTM X, dynamic headspace concentration and DART-MS was evaluated to determine if the approach could generate information rich chemical attribute signatures (CAS) for smokeless powder. CarbopackTM X is a graphitized carbon material that has been employed for the collection of various volatile and semi-volatile organic compounds. The goal of using CarbopackTM X coated wire mesh was to increase the collection efficiency of smokeless powder in comparison to traditional swabbing and swiping methods. DART is an ambient ionization technique that permits analysis of a variety of samples in seconds with minimal to no sample preparation and offers several advantages over conventional methods. Heating time, heating temperature and flow rate for dynamic headspace concentration were optimized using Hodgdon Lil’ Gun smokeless powder. DART-MS was compared to GC-MS and validated using the National Institute of Standards and Technology reference material 8107 (NIST RM 8107) smokeless powder standard. Additives and energetic materials from unburnt and burnt smokeless powders were rapidly and efficiently captured by the CarbopackTM X coated wire mesh and successfully detected and identified using DART-MS. The DART source temperature was evaluated with the goal of providing the most efficient desorption of the analytes adsorbed onto the wire mesh. For this to be a robust approach in forensic analysis, chemometric analysis employing predictive models was used to simplify the data and increase the confidence of assigning a mass spectrum to a particular powder. Predictive models were constructed using the machine learning techniques available in Analyze IQ Lab and evaluated for their performance in classifying three smokeless powders: Alliant Reloder 19, Hodgdon LEVERevolution and Winchester Ball 296. The models were able to accurately predict the presence or absence of these three powders from burnt residues with error rates that were less than 4%. This approach has demonstrated the capability of generating comparable data and sensitivity in a significantly shorter amount of time in comparison to GC-MS. In addition, DART-MS also permits the detection of targeted analytes that are not amenable to GC-MS. The speed and efficiency associated with both the sample preparation technique and DART-MS, and the ability to employ chemometric analysis to the generated data demonstrate an attractive and viable alternative to conventional techniques for smokeless powder analysis.

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.