Forensic Analysis and Differentiation of Black Powder and Black Powder Substitute Chemical Signatures by Infrared Thermal Desorption-DART-MS

The development of screen-printed electrodes modified with gold and copper nanostructures for analysis of gunshot residue and low explosives

Due to their portability, sensitivity, and ease of use, electrochemical sensors have recently become a popular method for rapid, on-site analysis. This study presents a proof of principle for the application of modified screen-printed carbon electrodes (SPCEs) for the detection of signature metals (Pb, Sb, and Zn) commonly found in gunshot residue (GSR), as well as for the detection of nitrate/nitrite in organic GSR and low explosives. To achieve these two aims, we have examined various electrode surface modifications. For metal detection, SPCEs were modified by electrodeposition of gold to improve sensitivity. GSR samples taken from two types of cartridge cases and shooting-related surfaces were analyzed using the Au-modified SPCEs. For nitrate/nitrite analysis, further electrode surface modifications were carried out by depositing Cu(II) onto the Au-SPCEs to enhance signal through catalytic activity of the copper surfaces. Both unburned and burned forms of black powder samples, as well as burned smokeless powder, were then analyzed using the Cu/Au-SPCEs. In conclusion, due to their low cost and portability, these sensors should prove useful for rapid forensic examination.

In-Line Thermal Desorption and Dielectric Barrier Discharge Ionization for Rapid Mass Spectrometry Detection of Explosives

Thermal desorption (TD) of wipe-based samples was coupled with an in-line dielectric barrier discharge ionization (DBDI) source and rugged compact time-of-flight mass spectrometer (MS) for the detection of explosives, propellants, and postblast debris. The chromatography-free TD-DBDI-MS platform enabled rapid and sensitive detection of organic nitramine, nitrate ester, and nitroaromatic explosives as well as black powder and black powder substitute propellants. Parametric investigations characterized the response to TD temperature and optimized DBDI voltage, aerodynamically assisted entrainment, and fragmentation through in-source collision induced dissociation (isCID). Excess nitrate generated by the DBDI source yielded predominantly nitrate-adduct formation. Subnanogram sensitivities were demonstrated for all explosives investigated, except for nitroglycerin, specifically due to its volatility. Further, most analytes/explosives exhibited tens of picograms sensitivities. The platform also demonstrated the detection of propellant and military explosives from postblast debris. The TD-DBDI-MS system performed well without the need for aerodynamically assisted entrainment (and the associated rough pump), which along with requiring no additional gases (i.e., N2 or He) or solvents, aid in potential field deployment. The ease of TD-DBDI attachment and removal added trace solid or liquid residue detection to the rugged mass spectrometer, designed primarily for the analysis of volatile organic and inorganic compounds.

Portable Instrumentation for Ambient Ionization and Miniature Mass Spectrometers

We critically evaluate the current status of portable mass spectrometry (pMS), particularly where this aligns with ambient ionization. Assessing the field of pMS can be quite subjective, especially in relation to the portable aspects of design, deployment, and operation. In this review, we discuss what it means to be portable and introduce a set of criteria by which pMS and ambient ionization sources can be assessed. Moreover, we consider the recent literature in terms of the most popular and significant advances in portable instrumentation for ambient ionization and miniature mass spectrometers. Finally, emerging trends and exciting future prospects are discussed and some recommendations are offered.

Comparison of direct analysis in real-time mass spectrometry, atmospheric solids analysis probe-mass spectrometry, and ion mobility spectrometry for ensuring food safety by rapid screening of poppy seeds

The opium poppy (Papaver somniferum) is a global commercial crop that has been historically valued for both medicinal and culinary purposes. Naturally occurring opium alkaloids including morphine, codeine, thebaine, noscapine, and papaverine are found primarily in the latex produced by the plant. If the plant is allowed to fully mature, poppy seeds that do not contain the opium alkaloids will form within the pods and may be used in the food industry. It is possible for the seeds to become contaminated with alkaloids by the latex during harvesting, posing a potential health risk for consumers. In the USA, there have been more than 600 reported adverse events including 19 fatalities that may be linked to the consumption of a contaminated poppy-containing product such as home-brewed poppy seed tea. Unwashed poppy seeds and pods may be purchased over the Internet and shipped worldwide. The Forensic Chemistry Center, US Food and Drug Administration (FDA) has evaluated several mass spectrometers (MS) capable of rapid screening to be used for high-throughput analysis of samples such as poppy seeds. These include a direct analysis in real-time (DART) ambient ionization source coupled to a single-quadrupole MS, an atmospheric solids analysis probe (ASAP) ionization source coupled to the same MS, and ion mobility spectrometers (IMS). These instruments have been used to analyze 17 poppy seed samples for the presence of alkaloids, and the results were compared to data obtained using liquid chromatography with mass spectral detection (LC-MS/MS). Results from the 17 poppy seed samples indicate that the DART-MS, ASAP-MS, and IMS devices detect many of the same alkaloids confirmed during the LC-MS/MS analyses, although both the false-positive and false-negative rates are higher, possibly due to the non-homogeneity of the samples and the lack of chromatographic separation.

A feasibility study of direct analysis in real time-mass spectrometry for screening organic gunshot residues from various substrates

This study reports the use of direct analysis in real time-mass spectrometry (DART-MS) for the detection of organic gunshot residues (OGSR) in a variety of matrices of interest for forensics, customs, and homeland security. Detection limits ranged from (0.075 to 12) ng, with intra- and inter-day reproducibility below 0.0012% CV. The collection of mass spectra at multiple in-source collision-induced dissociation (is-CID) voltages produced distinctive mass spectral signatures with varying levels of fragmentation and allowed differentiation of isomers. To test method performance, a collection of 330 authentic specimens from various substrates were analyzed - (1) neat smokeless powders, (2) spent cartridge cases, (3) burnt particles removed from clothing via carbon stubs or (4) with tweezers, and hand samples from (5) non-shooters, and (6) shooters. A subset of hand specimens (n = 80) was further analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for confirmation and comparison. Seven types of ammunition from five manufacturers and two calibers were monitored for OGSR profiles with similar compositions observed for paired sets (e.g., unburnt smokeless powder and the respective residues on spent cartridges, clothing, and hands). No false positives were observed across all datasets. A 100% true positive rate (TPR) was observed for all substrates except the shooters' hands. Depending on the ammunition type and classification criteria, the shooters' hands exhibited a TPR ranging from 19% to 73%. The results show that DART-MS is feasible and versatile for fast screening of OGSR across various substrates but may benefit from alternative approaches to improve detection at trace levels.

Differentiation of Body Fluid Stains Using a Portable, Low-Cost Ion Mobility Spectrometry Device-A Pilot Study

The identification and recovery of suspected human biofluid evidence can present a bottleneck in the crime scene investigation workflow. Crime Scene Investigators typically deploy one of a number of presumptive enhancement reagents, depending on what they perceive an analyte to be; the selection of this reagent is largely based on the context of suspected evidence and their professional experience. Positively identified samples are then recovered to a forensic laboratory where confirmatory testing is carried out by large lab-based instruments, such as through mass-spectrometry-based techniques. This work proposes a proof-of-concept study into the use of a small, robust and portable ion mobility spectrometry device that can analyse samples in situ, detecting, identifying and discriminating commonly encountered body fluids from interferences. This analysis exploits the detection and identification of characteristic volatile organic compounds generated by gentle heating, at ambient temperature and pressure, and categorises samples using machine learning, providing investigators with instant identification. The device is shown to be capable of producing characteristic mobility spectra using a dual micro disc pump configuration which separates blood and urine from three visually similar interferences using an unsupervised PCA model with no misclassified samples. The device has the potential to reduce the need for potentially contaminating and destructive presumptive tests, and address the bottleneck created by the time-consuming and laborious detection, recovery and analysis workflow currently employed.

Rapid Chemical Screening of Microplastics and Nanoplastics by Thermal Desorption and Pyrolysis Mass Spectrometry with Unsupervised Fuzzy Clustering

The transport and chemical identification of microplastics and nanoplastics (MNPs) are critical to the concerns over plastic accumulation in the environment. Chemically and physically transient MNP species present unique challenges for isolation and analysis due to many factors such as their size, color, surface properties, morphology, and potential for chemical change. These factors contribute to the eventual environmental and toxicological impact of MNPs. As analytical methods and instrumentation continue to be developed for this application, analytical test materials will play an important role. Here, a direct mass spectrometry screening method was developed to rapidly characterize manufactured and weathered MNPs, complementing lengthy pyrolysis-gas chromatography-mass spectrometry analysis. The chromatography-free measurements took advantage of Kendrick mass defect analysis, in-source collision-induced dissociation, and advancements in machine learning approaches for the data analysis of complex mass spectra. In this study, we applied Gaussian mixture models and fuzzy c-means clustering for the unsupervised analysis of MNP sample spectra, incorporating clustering stability and information criterion measurements to determine latent dimensionality. These models provided insight into the composition of mixed and weathered MNP samples. The multiparametric data acquisition and machine learning approach presented improved confidence in polymer identification and differentiation.

Explosive Odor Signature Profiling: A Review of recent advances in technical analysis and detection

With the ever-increasing threat of improvised explosive devices (IEDs) and homemade explosives (HME) both domestically and abroad, detection of explosives and explosive related materials is an area of urgent importance for preventing terrorist activities around the globe. Canines are a common biological detector used in explosive detection due to their enhanced olfactory abilities, high mobility, efficient standoff sampling, and optimal identification of vapor sources. While other sensors based on different principles have emerged, an important concept for the rapid field detection of explosives is understanding key volatile organic compounds (VOCs) associated with these materials. Explosive detection technology needs to be on par with a large number of threats including an array of explosive materials as well as novel chemicals used in the manufacture of IEDs. Within this much needed area of research for law enforcement and homeland security applications, several studies have sought to understand the explosive odor profile from a range of materials. This review aims to provide a foundational overview of these studies to provide a summary of instrumental analysis to date on the various types of explosive odor profiles evaluated focusing on the experimental approaches and laboratory techniques utilized in the chemical characterization of explosive vapors and mixtures. By expanding upon these concepts, a greater understanding of the explosive vapor signature can be achieved, providing for enhanced chemical and biological sensing of explosive threats as well as expanding upon existing laboratory-based models for continued sensor development.

Online coupling of matrix solid-phase dispersion to direct analysis in real time mass spectrometry for high-throughput analysis of regulated chemicals in consumer products

The current work is the first study on online coupling of matrix solid-phase dispersion (MSPD) to direct analysis in real time mass spectrometry (DART-MS) bridging with solid-phase analytical derivatization (SPAD) based on a graphene oxide nanosheets (GONs)-coated cotton swab. Proof-of-concept demonstrations were explored for high-throughput analysis of a diversity of regulated chemicals in consumer products such as textiles, toys, and cosmetics. On-demand sorbent combinations were blended with samples, packed into MSPD columns, and mounted on a homemade 3D-printed rack module for automated sample feeding. To achieve good synergy between MSPD and DART-MS, a cotton swab with a conical tip deposited with GONs was attached to the bottom of the MSPD column. The swabs serve as a solid-phase microextraction probe for convenient enrichment of the eluted analytes from MSPD, thermal desorption of the enriched analytes by DART, and sensitive detection by a hybrid quadrupole-Orbitrap mass spectrometer. Furthermore, the utility of an on-swab SPAD strategy was demonstrated for the detection of formaldehyde by use of the derivatizing reagent of dansyl hydrazine, contributing to improved ionization efficiency without compromising the overall coherence of the analytical workflow. The MSPD-DART-MS methodology was systematically optimized and validated, obtaining acceptable recovery (71.7-110.3%), repeatability (11.8-19.3%), and sensitivity (limits of detection and quantitation in the ranges of 6.2-19.5 and 23.7-75.9 μg/kg) for 32 target analytes. The developed protocol streamlined sample extraction, clean-up, desorption, ionization, and detection, highlighting the appealing potential for high-throughput analysis of samples with complex matrices.

Plasma-based ambient mass spectrometry: Recent progress and applications

Ambient mass spectrometry (AMS) has grown as a group of advanced analytical techniques that allow for the direct sampling and ionization of the analytes in different statuses from their native environment without or with minimum sample pretreatments. As a significant category of AMS, plasma-based AMS has gained a lot of attention due to its features that allow rapid, real-time, high-throughput, in vivo, and in situ analysis in various fields, including bioanalysis, pharmaceuticals, forensics, food safety, and mass spectrometry imaging. Tens of new methods have been developed since the introduction of the first plasma-based AMS technique direct analysis in real-time. This review first provides a comprehensive overview of the established plasma-based AMS techniques from their ion source configurations, mechanisms, and developments. Then, the progress of the representative applications in various scientific fields in the past 4 years (January 2017 to January 2021) has been summarized. Finally, we discuss the current challenges and propose the future directions of plasma-based AMS from our perspective.

Application of direct analysis in real-time mass spectrometry (DART-MS) in forensic science: a comprehensive review

Background

As the rate of crime is constantly increasing, the workload on the forensic analyst also piles up. The availability of a limited number of seized samples makes it crucial to directly analyze the sample, thereby preventing wastage in the prior steps of sample preparation. Due to such needs, the forensic community is consistently working on broadening the usage of direct analysis in real-time mass spectrometry (DART-MS). DART-MS is a relatively new technique for rapid mass spectral analysis. Its use for chemical analysis credits its ability to analyze the sample at atmospheric pressure.

Main body

This article gives insight into the ionization mechanisms, data analysis tools, and the use of hyphenated techniques like thermal-desorption-DART-MS, infrared-thermal-desorption-DART-MS, Joule-heating thermal-desorption-DART-MS, etc. This review summarizes the applications of DART-MS in the field of Forensic Science reported from 2005 to 2021. The applications include analysis of drugs, warfare agents, gun-shot residues, ink differentiation, and other forensically relevant samples. The paper also presents the relation between the type of DART-MS technique and the ionization mode used for a particular class of compounds.

Conclusion

The review follows that the high-resolution mass-spectrometers or low-resolution mass-spectrometers systems in the positive or negative mode were highly dependent on the type of analyte under investigation. Drugs, inks, dyes, and paints were mainly analyzed using the positive ionization mode in the HRMS technique. The examinations of fire accelerants predominantly used the positive ionization mode in the LRMS technique. Moreover, the limit of detection values obtained from the qualitative screening of street drugs were of ppb level, indicating high sensitivity of DART-MS. Considering the work done in the past years, there are potential future research needs of this technology, especially in forensic science.

Graphical Abstract

DART-MS Spectral Similarity of Infrared Thermally Desorbed Solid Particulate and Solution Cast Propellant Samples

Security and forensic applications employ test and reference materials to develop, calibrate, and validate analytical instrumentation such as mass spectrometry for the trace detection and chemical analysis of target analytes. An emerging class of target analytes includes homemade fuel oxidizer explosives based on pyrotechnics, propellants, and powder mixtures. Test materials for these compounds must appropriately and accurately embody the physical and chemical nature of the threat. Precision liquid deposition methods have long been employed for creation of trace level test materials. Mass spectral similarity and chemical signature differences between solid particulate and solution cast (i.e., liquid deposited) propellant samples were investigated by infrared thermal desorption direct analysis in real time mass spectrometry (IRTD-DART-MS). Differences in the mass spectra and ion distributions of solid and liquid deposited black powders and black powder substitutes were observed. These differences were attributed to chemical processes (e.g., degradation) and physical differences in the crystal formation, spatial distribution, morphology, and size. The production and deposition of test and reference materials remain critical to developing new technologies and detecting evolving threats.

Forensic applications of DART-MS: A review of recent literature

The need for rapid chemical analyses and new analytical tools in forensic laboratories continues to grow due to case backlogs, difficult-to-analyze cases, and identification of previously unseen materials such as new psychoactive substances. To adapt to these needs, the forensics community has been pursuing the use of ambient ionization mass spectrometry, and more specifically direct analysis in real time mass spectrometry (DART-MS), for a wide range of applications. From the inception of DART-MS forensic applications have been researched with demonstrations ranging from drugs of abuse to inorganic gunshot residue to printer inks to insect identification. This article presents a review of research demonstrating the use of DART-MS for forensically relevant samples over the past five years. To provide more context, background on the technique, sampling approaches, and data analysis methods are presented along with a discussion on the potential future and research needs of the technology.

Inorganic oxidizer detection from propellants, pyrotechnics, and homemade explosive powders using gradient elution moving boundary electrophoresis

Advancement in rapid targeted chemical analysis of homemade and improvised explosive devices is critical for the identification of explosives-based hazards and threats. Gradient elution moving boundary electrophoresis (GEMBE), a robust electrokinetic separation technique, was employed for the separation and detection of common inorganic oxidizers from frequently encountered fuel-oxidizer mixtures. The GEMBE system incorporated sample and run buffer reservoirs, a short capillary (5 cm), an applied electric field, and a pressure-driven counterflow. GEMBE provided a separation format that allowed for continuous injection of sample, selectivity of analytes, and no sample cleanup or filtration prior to analysis. Nitrate, chlorate, and perchlorate oxidizers were successfully detected from low explosive propellants (e.g., black powders and black powder substitutes), pyrotechnics (e.g., flash powder), and tertiary explosive mixtures (e.g., ammonium nitrate- and potassium chlorate-based fuel-oxidizer mixtures). Separation of these mixtures exhibited detection without interference from a plethora of additional organic and inorganic fuels, enabled single particle analysis, and demonstrated semiquantitative capabilities. The bulk counterflow successfully excluded difficult components from fouling the capillary, yielding estimated limits of detection down to approximately 10 μmol/L. Finally, nitrate was separated and detected from postblast debris collected and directly analyzed from two nitrate-based charges.

Chemical analysis and classification of black pepper (Piper nigrum L.) based on their country of origin using mass spectrometric methods and chemometrics

The current study applied gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and thermal desorption direct analysis in real-time mass spectrometry (TD-DART-MS) methods to the analysis of black pepper (Piper nigrum L.) samples from different countries. The black pepper powder samples were analyzed directly by TD-DART-MS without any extraction, but for GC-MS and LC-MS methods, a methanol extraction procedure was employed before the analysis. Various compounds, such as piperamides and terpenes, were detected. Partial least squares-discriminant analysis (PLS-DA) was used to classify black pepper samples based on their origins. Total ion mass spectrum (TMS) data profiles from GC-MS, LC-MS, and TD-DART-MS methods were constructed and evaluated for the performance of classification. A cubic-root data transformation was tested in the data preprocessing and found to be effective for improving the classification rates. The average classification rates of PLS-DA models with GC-MS-cubic-root-TMS, LC-MS-cubic-root-TMS, and DART-MS-cubic-root-TMS data representations were 94.1 ± 0.6%, 87.7 ± 0.6%, and 97.0 ± 0.3% respectively, for 100-time bootstrapped-Latin-partition cross-validation. This study presents for the first time the analysis of plant-based food materials by using TD-DART-MS, and it has been demonstrated as a simple and high-throughput method for classification studies.

Solvent-free, Noncontact Electrostatic Sampling for Rapid Analysis with Mass Spectrometry: Application to Drugs and Explosives

A hand-held Van de Graaf generator is used to apply a high voltage, negligible current electrostatic potential to a wire mesh positioned in close proximity to a particle-laden surface in order to collect those particles for analysis. The electrostatic field effects transfer particles to the mesh without a requirement for mechanical contact between mesh and surface. Analysis of chemicals present in the sampled particles is completed by thermal desorption electrospray ionization. The utility of the method for noncontact sampling is demonstrated using solid drug powder samples, and inorganic explosives dispersed either on solid surfaces or in sand/soil in order to simulate common interfering matrices that might be encountered in the forensic environment. A metal mesh sampling substrate is utilized instead of traditional polymer-based swabs in order to permit thermal desorption at higher temperatures. The method leaves no visible trace of sampling leaving details such as a fingerprint image unperturbed, as demonstrated using fluorescence photography. Direct sampling of trace particles from hard surfaces and skin documents flexibility in the choice of sampling substrates, desorption temperatures, and sampling times. The potential of the device for use in forensic analyses is detailed.

Trace Detection and Chemical Analysis of Homemade Fuel-Oxidizer Mixture Explosives: Emerging Challenges and Perspectives

The chemical analysis of homemade explosives (HMEs) and improvised explosive devices (IEDs) remains challenging for fieldable analytical instrumentation and sensors. Complex explosive fuel-oxidizer mixtures, black and smokeless powders, flash powders, and pyrotechnics often include an array of potential organic and inorganic components that present unique interference and matrix effect difficulties. The widely varying physicochemical properties of these components as well as external environmental interferents and background challenge many sampling and sensing modalities. This review provides perspective on these emerging challenges, critically discusses developments in sampling, sensors, and instrumentation, and showcases advancements for the trace detection of inorganic-based explosives.

Evaluation of the Deterioration State of Archaeological Wooden Artifacts: A Nondestructive Protocol based on Direct Analysis in Real Time - Mass Spectrometry (DART-MS) Coupled to Chemometrics

Evaluating the deterioration state of archeological wood is obligatory before the preservation of archeological wooden artifacts. Herein, a nondestructive, accurate, and rapid methodology is first developed via direct analysis in real time-mass spectrometry (DART-MS) with chemometrics to classify archeological wood and recent wood into 3 groups according to their deterioration states. As water in wooden artifacts probably affected the ion fragmentation process during DART-MS, ions responsible for evaluating the deterioration state were separately screened toward waterlogged archeological wood and dried archeological wood by partial least-squares discriminant analysis (PLS-DA). The well-defined separation of severely decayed archeological wood, moderately decayed archeological wood and recent wood was revealed in PLS-DA models. Twenty and 27 wood fragment ions were further screened as key variables to evaluate the deterioration state of waterlogged archeological wood and dried archeological wood, respectively. They were tentatively identified as ions of lignin monomeric compositions, lignin dimers, lignin trimers, and oligosaccharides. Results strongly suggested that differences in the structure and relative abundances of wood cell wall components accounts for the evaluation of deterioration state by DART-MS coupled to chemometrics. PLS-DA models provided R²Y = 0.836, Q² = 0.817, and R²Y = 0.754, Q² = 0.682 were then established separately using mass spectral fingerprints of respective potential predictive wood fragment ions. Furthermore, archeological woods, consisting of Castanopsis, Quercus, Idesia, Populus, and Cunninghamia species and with an average MWC range of 103-465%, were used as an external validation set and evaluated with the methodology developed herein and the MWC criteria. Results showed that DART-MS coupled to chemometrics could accurately predict the inhomogeneous deterioration states of archeological wooden artifacts and avoid the interference of inorganic deposits, in comparison with the MWC criteria.

Interpol review of detection and characterization of explosives and explosives residues 2016-2019

This review paper covers the forensic-relevant literature for the analysis and detection of explosives and explosives residues from 2016-2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/Resources/Documents#Publications.

Direct analysis in real time coupled with quadrupole-Orbitrap high-resolution mass spectrometry for rapid analysis of pyrethroid preservatives in wooden food contact materials

A methodology is presented for the determination of four pyrethroid (PYR) preservatives in wooden food contact materials (FCMs) using direct analysis in real time (DART) coupled with quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS). The sampling mode and critical parameters of the DART-Q-Orbitrap HRMS protocol were systematically investigated. Good linearity was achieved for the four analytes with correlation coefficients all greater than 0.99. The limits of detection (LODs) and limits of quantitation (LOQs) of the method were in the range of 0.04-0.20 mg kg^-1 and 0.10-0.50 mg kg^-1, respectively. The mean recoveries ranged from 72.1% to 82.7% with relative standard deviations (RSDs) from 5.2% to 11.8% at three spiked levels. The developed method was proved to be suitable for rapid screening of PYRs in complex wooden FCM samples to ensure product safety and consumer health.

Emerging techniques for the detection of pyrotechnic residues from seized postal packages containing fireworks

High volume screening of parcels with the aim to trace the illegal distribution and selling of fireworks using postal services is challenging. Inspection services have limited manpower and means to perform extensive visual inspection. In this study, the presence of solid pyrotechnic residues collected from cardboard shipping parcels containing fireworks was investigated for direct in-field chemical detection. Two emerging trace detection techniques, i.e., capillary electrophoresis (CE)-based inorganic oxidizer detector and infrared thermal desorption (IRTD) coupled with direct analysis in real time mass spectrometry (DART-MS), were investigated for their potential as screening tools. Detection of non-visible pyrotechnic trace residues from real-case seized parcels was demonstrated using both screening techniques. However, the high nitrate background in the commercial CE system complicated its screening for black powder traces. IRTD-DART-MS allowed differentiation between flash and black powder by identification of the molecular inorganic ions. Compared to the portable CE instrument, rapid screening using IRTD-DART-MS is currently limited to laboratory settings. The capabilities of these emerging techniques established solid particle and trace residue chemical detection as interesting options for parcel screening in a logistic setting.

Filter Cone Spray Ionization Coupled to a Portable MS System: Application to On-Site Forensic Evidence and Environmental Sample Analysis

The complexity of field-borne sample matrices and the instrumental constraints of portable mass spectrometers (MS) often necessitate that preparative steps are added prior to ambient MS methods when operated on-site, but the corresponding decrease in throughput and experimental simplicity can make field operation impractical. To this end, we report a modified ambient MS method, filter cone spray ionization (FCSI), specifically designed for simple, yet robust, processing of bulk forensic evidence and environmental samples using a fieldable MS system. This paper-crafted source utilizes low-cost laboratory consumables to produce a conical structure that serves as a disposable, spray-based ionization source. Integrated extraction and filtration capabilities mitigate sample heterogeneity and carryover concerns and expedite sample processing, as characterized through the analysis of a variety of authentic forensic evidence types (e.g., abused pharma tablets, counterfeit/adulterated tablets, crystal-based drugs, synthetic marijuana, toxicological specimens) and contaminated soil samples. The data presented herein suggests that the FCSI-MS design could prove robust to the rigors of field-borne, bulk sample screening, overcoming the inefficiencies of other ambient MS methods for these sample classes. Novel applications of FCSI-MS are also examined, such as the coupling to trace evidence vacuum filtration media.