Forensic science has been a prominent pillar of research at NIST since the release of 2009 National Academies of Sciences report Strengthening Forensic Science in the Unites States: A Path Forward. While the forensics research portfolio across NIST is broad, within MMSD the focus is specifically on forensic chemistry disciplines – seized drugs analysis, ignitable liquids analysis, gunshot residue analysis, and trace evidence. Within MMSD we have prioritized collaboratively addressing current forensic chemistry measurement challenges. To accomplish this, NIST scientists work directly with forensic practitioners at the local, state, federal, and international levels to identify pressing needs in the community and develop innovative, effective solutions that are practical and implementable. The products of this research are tangible methods, technologies, tools, data, and materials that enable forensic practitioners to analyze casework with increased safety, effectiveness, objectivity.
Feature Story — Safe, Efficient, Reliable: New Science in the Fight Against Killer Drugs
MMSD has unique tangible and intangible capabilities that have enabled the division to be a leader in addressing forensic chemistry measurement challenges. Laboratories within MMSD house instrumentation that is commonplace in most forensic laboratories (e.g., gas chromatography mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR)) as well as emerging, next-generation techniques (e.g., ambient ionization mass spectrometry and spectroelectrochemistry). This broad suite of technology enables MMSD scientists to assist laboratories in developing solutions that can be implemented today, while also demonstrating what can be done in the near future. In addition to chemical analysis, MMSD also has unique particle visualization capabilities that allow us to demonstrate and study the spread of material when handled in routine forensic analyses. MMSD has spent significant time and energy in developing strong ties with forensic practitioners from local, state, federal, and international laboratories. These partnerships ensure the research being conducted within the Division will ultimately benefit the end-user.
Improving Safety, Speed, and Objectivity of Seized Drug Analysis
The analysis of seized drugs is the most frequently requested examination in forensic science. In recent years this discipline has faced several analytical challenges due to i) the emergence of synthetic opioids and other novel psychoactive substances, ii) rapidly changing drug landscapes, iii) increased potency and toxicity of the compounds that are encountered, and iv) changes in legalization of different compounds. MMSD supports drug chemists across the country by providing technical expertise on the safe handling of compounds, the development of new methods for screening and confirmation of compounds, and the creation of new data analysis or data interpretation approaches to enable more objective reporting.
- New Analytical Tools and Methods for Seized Drug Analysis — The analytical challenges being faced by drug chemists mentioned above have necessitated the need to investigate new technologies that can identify never before seen compounds, often at low concentrations, in the presence of diluents, and in a timely fashion. Working with practitioners, we identify analytical techniques that could address these needs and develop the necessary methods, libraries, and validation studies. Recently, efforts have concentrated on direct analysis in real time mass spectrometry (DART-MS) and rapid gas chromatography mass spectrometry (GC-MS). In addition to method development and validation, we also work with practitioners on implementing these new technologies – aiding in internal validations, trainings, and providing assistance with troubleshooting and interpretation of unusual data.
- Search Algorithms and Spectral Libraries for Ambient Ionization Mass Spectrometry — A major barrier to implementation of ambient ionization mass spectrometry techniques like DART-MS into forensic laboratories is the lack of spectral databases and data processing tools tailored to the application. This effort seeks to overcome this barrier through the creation of new search algorithms and data interpretation methods specifically designed for the complexity of these techniques. Mass spectral databases to support these algorithms are also being developed and maintained. This work is being accomplished in collaboration with the Biomolecular Measurement Division within MML and the Applied and Computational Mathematics Division within ITL.
- Novel Workflows for Seized Drug Analysis — Adoption of new technology into an analytical workflow provides a logical opportunity for laboratories to rethink other aspects of sample handling and sample analysis. With the adoption of advanced screening technologies like DART-MS or rapid GC-MS, practitioners are now able to obtain more complete and accurate information about a sample, sooner. In this effort NIST scientists work alongside practitioners to identify ways that this new information can be used to better tailor confirmation analyses, for instance by implementing confirmatory methods specifically designed to differentiate isomeric species. In addition to rethinking and implementing new workflows, NIST scientists work with practitioners and laboratory management to capture and understand the gains these novel workflows have on speed, safety, and objectivity.
- Particle Visualization to Inform Chemist Safety, Data Integrity, and Sampling — This effort uses advanced flow visualization and flow diagnostic techniques to image the generation, evolution, transport, and ultimate fate of microscopic particles that are generated during forensically-relevant activities. These activities include the manufacturing of illicit drugs of abuse, the handling of seized drug materials in forensic laboratories, and the indoor discharge of firearms. Results of this work help inform law enforcement, forensic practitioners, and researchers on trace contamination spread. This ultimately helps inform best practices for sampling and collecting trace residues as well as minimizing the generation of unwanted contamination.
Rapid Screening to Enhance Fire Debris and Organic Gunshot Residue Analyses
Other major chemistry efforts at many forensic laboratories focus on the identification of ignitable liquids in fire debris (to determine the possible cause of a fire) and the identification of gunshot residue (to determine if a person or object was present when a firearm was used). Sample preparation and analysis for these samples can take tens of hours or more, thereby limiting throughput. MMSD researchers are investigating the utility of screening methods with two main purposes in mind: to provide insight into sample contents prior to confirmatory analysis and to increase sample throughput by eliminating the need for further analysis of negative samples.
- Rapid Screening of Ignitable Liquids — Recent work has focused on using rapid gas chromatography-mass spectrometry (GC-MS) as a novel method to separate and identify sample components in ignitable liquids and fire debris samples. We are also exploring the application of ambient ionization mass spectrometry techniques, specifically DART-MS, for rapid screening of ignitable liquids directly from original sample containers (e.g., paint cans) with no sample preparation. Current efforts for both the rapid GC-MS and DART-MS approaches involve working with practitioners to generate spectral libraries for use in preliminary identifications of ignitable liquids. The overall goal is the development of appropriate screening workflows with optimized analysis methods.
- Rapid Screening of Organic Gunshot Residue — Traditionally, forensic gunshot residue analysis has focused on the detection and identification of inorganic particles consisting of lead, barium, and antimony. Newer ammunitions, however, have largely removed these compounds in favor of more environmentally friendly, less toxic, organic alternatives, creating a need for updated analytical methods. This effort has focused on using DART-MS to rapidly screen for organic gunshot residues. Specifically, efforts have surrounded the optimization and validation of DART-MS methods, discrimination of shooter versus bystander based on the chemical makeup of these signatures, and discrimination of ammunition types.
Advancing Inorganic Trace Evidence Analysis
While many areas of forensic chemistry focus on the identification and analysis of organic compounds, several sub-disciplines in trace evidence seek to leverage differences or similarities in the inorganic makeup of compounds to determine if a questioned and known sample came from a same source. MMSD efforts in this area of forensic chemistry seek to bolster measurement rigor and availability of standards for traditional analyses (e.g., glass) while also looking to develop metrology to support novel applications (e.g., 3-D printed firearms or ghost guns).
- Advancing the Field of Glass Analysis — The glass research efforts are focused on improving the field of glass evidence analysis by developing new matrix-matched glass standards, evaluating more objective approaches to evidence interpretation, and ensuring documentary standards are fit-for-purpose for modern glass formulations and state-of-the-art instrumentation. These research efforts include the quantitative analysis of new matrix-matched float glass standards for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) calibration, the development of modern glass datasets that can be used to assign a significance to the evidence, and performance evaluation of modern micro X-ray fluorescence spectroscopy (µXRF) systems for glass analysis.
- Elemental Analysis of 3D-Printed Ghost Guns — This effort is focused on the elemental characterization of a relatively novel type of forensic trace evidence that has recently become more prevalent in casework, polymer filaments used in 3D-printers. The utility of µXRF for the forensic analysis of 3D-printed polymers is being evaluated based on discriminating power, precision, and error rates (false inclusions and false exclusions). These fundamental characterization studies will aid in the development of a methodology for the forensic comparison of 3D-printed polymeric materials.