Fabrication and characterization of gelatin-based test materials for verification of trace contraband vapor detectors.

This work describes a method to produce inexpensive and field deployable test materials that can be used to verify the performance of trace contraband vapor detection systems such as ion mobility spectrometers (IMS) currently deployed worldwide for explosives, narcotics, and chemical warfare agent (CWA) detection. Requirements for such field deployable test materials include long shelf life, portability, and low manufacturing costs. Reported here is a method for fabricating these test materials using encapsulation of high vapor pressure compounds, such as methyl salicylate (MS), into a gelatin matrix. Gelatin serves as a diffusion barrier allowing for controlled and sustained release of test vapors. Test materials were prepared by incorporating serial dilutions of MS into gelatin, which provide controlled analyte vapor release over 3 to 4 orders of magnitude of instrument response. The test materials are simple to prepare and have been shown to be stable for at least one year under controlled laboratory conditions.

The Opioid Epidemic: Moving Toward an Integrated, Holistic Analytical Response.

In many jurisdictions, public safety and public health entities are working together to enhance the timeliness and accuracy of the analytical characterization and toxicology testing of novel synthetic opioids. The improved sharing and early detection of these analytical data are intended to inform surveillance, interdiction efforts, patient intervention and treatment, all of which are critical to curbing the opioid epidemic. Forensic practitioners working to identify novel synthetic opioids struggle to provide timely results when encountering new or unknown substances, such as the fentanyl analogs. These compounds, which mimic heroin in pharmacologic effect but can be far more potent, are inconsistently present in chemical identification libraries, and are currently largely unavailable as reference materials for analytical comparison. Additionally, federal, state and local governments as well as nongovernmental organizations require potency, toxicity and potential-for-abuse data to evaluate the potential health risks of emerging drug threats. Subsequent scheduling efforts and criminal prosecutions also require these thorough drug characterization studies. Pilot programs have demonstrated that early communication of real-time drug toxicity and analytical data significantly impacts the successful response to emerging opioids. High-quality, real-time, national-level data on chemical composition, toxicological test data, drug toxicity and overdoses, and analysis of seized materials by law enforcement are needed to track drug trends. However, the USA still lacks a national system to coordinate and communicate toxicology, medical and medical examiner and coroner data with the broader medical and law enforcement communities. Opportunities to address these gaps as well as recent advancements collected through interagency efforts and technical workshops in the toxicology and analytical chemistry communities are presented here. Opportunities for partnership, increased communication and expanding best practices to move toward an integrated, holistic analytical response are also explored.

The effect of reusing wipes for particle collection.

Sample collection for Ion Mobility Spectrometry (IMS) analysis is typically completed by swiping a collection wipe over a suspect surface to collect trace residues. The work presented here addresses the need for a method to measure the collection efficiency performance of surface wipe materials as a function of the number of times a wipe is used to interrogate a surface. The primary purpose of this study is to investigate the effect of wipe reuse, i.e., the number of times a wipe is swiped across a surface, on the overall particle collection and IMS response. Two types of collection wipes (Teflon coated fiberglass and Nomex) were examined by swiping multiple times, ranging from 0 to 1000, over representative surfaces that are common to security screening environments. Particle collection efficiencies were determined by fluorescence microscopy and particle counting techniques, and were shown to improve dramatically with increased number of swiping cycles. Ion mobility spectrometry was used to evaluate the chemical response of known masses of explosives (deposited after reusing wipes) as a function of the wipe reuse number. Results show that chemical response can be negatively affected, and greatly depends upon the conditions of the surface in which the wipe is interrogating. For most parameters tested, the PCE increased after the wipe was reused several times. Swiping a dusty cardboard surface multiple times also caused an increase in particle collection efficiency but a decrease in IMS response. Scanning electron microscopy images revealed significant surface degradation of the wipes on dusty cardboard at the micrometer spatial scale level for Teflon coated wipes. Additionally, several samples were evaluated by including a seven second thermal desorption cycle at 235°C into each swipe sampling interval in order to represent the IMS heating cycle. Results were similar to studies conducted without this heating cycle, suggesting that the primary mechanism for wipe deterioration is mechanical rather than thermal.

Biomimetic Sniffing Improves the Detection Performance of a 3D Printed Nose of a Dog and a Commercial Trace Vapor Detector.

Unlike current chemical trace detection technology, dogs actively sniff to acquire an odor sample. Flow visualization experiments with an anatomically-similar 3D printed dog's nose revealed the external aerodynamics during canine sniffing, where ventral-laterally expired air jets entrain odorant-laden air toward the nose, thereby extending the "aerodynamic reach" for inspiration of otherwise inaccessible odors. Chemical sampling and detection experiments quantified two modes of operation with the artificial nose-active sniffing and continuous inspiration-and demonstrated an increase in odorant detection by a factor of up to 18 for active sniffing. A 16-fold improvement in detection was demonstrated with a commercially-available explosives detector by applying this bio-inspired design principle and making the device "sniff" like a dog. These lessons learned from the dog may benefit the next-generation of vapor samplers for explosives, narcotics, pathogens, or even cancer, and could inform future bio-inspired designs for optimized sampling of odor plumes.

Method for combined biometric and chemical analysis of human fingerprints.

This paper describes a method for combining direct chemical analysis of latent fingerprints with subsequent biometric analysis within a single sample. The method described here uses ion mobility spectrometry (IMS) as a chemical detection method for explosives and narcotics trace contamination. A collection swab coated with a high-temperature adhesive has been developed to lift latent fingerprints from various surfaces. The swab is then directly inserted into an IMS instrument for a quick chemical analysis. After the IMS analysis, the lifted print remains intact for subsequent biometric scanning and analysis using matching algorithms. Several samples of explosive-laden fingerprints were successfully lifted and the explosives detected with IMS. Following explosive detection, the lifted fingerprints remained of sufficient quality for positive match scores using a prepared gallery consisting of 60 fingerprints. Based on our results (n = 1200), there was no significant decrease in the quality of the lifted print post IMS analysis. In fact, for a small subset of lifted prints, the quality was improved after IMS analysis. The described method can be readily applied to domestic criminal investigations, transportation security, terrorist and bombing threats, and military in-theatre settings.

Reliability of ion mobility spectrometry for qualitative analysis of complex, multicomponent illicit drug samples.

Ion mobility spectrometry (IMS) has been used for trace analysis of illicit drugs, but it can also provide reliable qualitative analysis of bulk forensic drug items, despite the complexity of these samples. The drug/drug and drug/excipient combinations representing over 80% of the samples reported by state and federal forensic laboratories over the past 7 years were compiled from reports of the National Forensic Laboratory Information System (NFLIS). From this set of materials, IMS detection windows were set for eight controlled substances, including methamphetamine, 3,4-methylenedioxymethamphetamine hydrochloride (MDMA), cocaine, heroin, fentanyl, hydrocodone, oxycodone, and alprazolam. The reduced mobilities of the eight controlled substances were measured over an extended period of time to determine variability with respect to the size of the detection windows. Uncertainties in reduced mobilities smaller than 0.001 cm(2)V(-1)s(-1) were obtained, and detection windows were set to between ±0.003 and ±0.005 cm(2)V(-1)s(-1). Reduced mobilities are instrument and operating condition dependent, and must be determined for each instrument. Peak overlaps are observed in the drug/drug combinations, but at least one controlled substance can be detected in each mixture. Excipient concentrations must be quite high (>75 wt%) in binary mixtures to interfere with the detection of the controlled substance. IMS can be used to identify many of the excipients, and can detect multiple (for these samples, as many as 4) substances in complex samples. Over-the-counter (OTC) tablet medications for cold, flu, and allergy relief can be distinguished from tablets containing controlled substances. Bulk materials, including tablets, are sampled simply by using a fine probe to restrict the amount of material transferred to the IMS substrate. IMS represents a distinct advantage over color tests for field analysis of illicit drugs, except in the case of cannabis/THC samples.