Accumulation of explosives in hair

The sorption of explosives (TNT, RDX, PETN, TATP, EGDN) to hair during exposure to their vapors is examined. Three colors of hair were simultaneously exposed to explosive vapor. Following exposure of hair, the sorbed explosive was removed by extraction with acetonitrile and quantified. Results show that sorption of explosives, via vapor diffusion, to black hair is significantly greater than to blond, brown or bleached hair. Furthermore, the rate of sorption is directly related to the vapor density of the explosive: EGDN > TATP >TNT > PETN > RDX. In some cases, the explosive-containing hair was subject to repeated washings with sodium dodecylsulfate or simply left out in an open area to determine the persistence of the explosive contamination. While explosive is removed from hair with time or washing, some persists. These results indicate that hair can be a useful indicator of explosive exposure/handling.     

Detection of explosives in hair using ion mobility spectrometry

Conventional explosives 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), and ethylene glycol dinitrate (EGDN) sorbed to hair can be directly detected by an ion mobility spectrometer (IMS) in E-mode (for explosives). Terrorist explosive, triacetone triperoxide (TATP), difficult to detect by IMS in E-mode, was detected in N-mode (for narcotics). Three modes of sample introduction to IMS vapor desorption unit were used: (i) placement of hair directly into the unit, (ii) swabbing of hair and placement of swabs (i.e., paper GE-IMS sample traps) into the unit, and (iii) acetonitrile extracts of hair positioned on sample traps and placed into the unit. TNT, NG, and EGDN were detected in E-mode by all three sample introduction methods. TATP could only be detected by the acetonitrile extraction method after exposure of the hair to vapor for 16 days because of lower sensitivity. With standard solutions, TATP detection in E-mode required about 10 times as much sample as EGDN (3.9 mug compared with 0.3 mug). IMS in N-mode detected TATP from hair by all three modes of sample introduction.     

Accumulation of explosives in hair--Part 3: Binding site study

This study extends previous work on the sorption of explosives to the hair matrix. Specifically, we have studied the interaction of 2,4,6-trinitrotoluene (TNT) and triacetone triperoxide (TATP) as a function of chemical pretreatment with acetonitrile, neutral and alkaline hydrogen peroxide, methanolic KOH and potassium permanganate, and the morphological changes that accompany these treatments. While differences in vapor pressure can account for quantitative differences between TNT and TATP sorption, both are markedly affected by the chemical rinses. Examination of the hair surface shows different degrees of smoothening following rinsing, suggesting that the attachment to hair is largely a surface phenomenon involving the 18-methyleicosanoic acid lipid layer. Density functional theory calculations were employed to explore possible nucleation sites of TATP microcrystals on the hair. We conclude that some of the sites on melanin granular surfaces may support nucleation of TATP microcrystals. Moreover, the calculations support the experimental finding that dark hair adsorbs explosives better than light hair.     

Preliminary investigation into the recovery of explosives from hair.

Sampling of hair has proved to be a useful non-invasive method for detecting illicit drugs. This study examined the viability of hair as a surface from which explosive traces can be recovered and showed that as little as one-hour vapour exposure can result in measurable traces of explosives. Contamination of the hair may result from direct contact with explosive particles or from secondary contact by hand. Also the paper demonstrates that hair can concentrate explosive from the ambient vapour of a variety of military explosives. It was found that the amount of TNT picked up by the hair increased with time of vapour exposure. The data also suggested that unwashed hair may pick up more TNT than washed hair.     

Analysis of Explosives by GC‐UV

A mixture of explosives was analyzed by gas chromatography (GC) linked to ultraviolet (UV) spectrophotometry that enabled detection in the range of 178–330 nm. The gas‐phase UV spectra of 2,4,6‐trinitrotoluene (TNT), 2,4‐dinitrotoluene (DNT), ethylene glycol dinitrate (EGDN), glycerine trinitrate (NG, nitroglycerine), triacetone triperoxide (TATP), and pentaerythritol tetranitrate (PETN) were successfully recorded. The most interesting aspect of the current application is that it enabled simultaneous detection of both the target analyte and its decomposition products. At suitable elevated temperatures of the transfer line between the GC instrument and the UV detector, a partial decomposition was accomplished. Detection was made in real time and resulted in overlaid spectra of the mother compound and its decomposition product. Hence, the presented approach added another level to the qualitative identification of the explosives in comparison with traditional methods that relies only on the detection of the target analyte. As expected, the decomposition product of EGDN, NG, and PETN was NO, while TATP degraded to acetone. DNT and TNT did not exhibit any decomposition at the temperatures used.     

Trends in explosive contamination

This study sought to assign a rough order of magnitude for the amount of explosive residue likely to be available in real-world searches for clandestine explosives. A variety of explosives (TNT, TATP, HMX, AN, RDX, PETN) in various forms (powder, flake, detonating cord, plastic) were carefully weighed or cut into containers, and the amount of residue inadvertently remaining on the work area, hands, or containers was quantified. This was used to evaluate the spillage potential of each explosive. The adhesion of each explosive to a glass surface was quantified from amount of explosive adhering to the inside of a glass vial into which the explosive had been placed and then removed by vigorous tapping. In powdered form, most of the explosives--TNT, PETN, RDX, HMX, and TATP--exhibited similar spillage and adhesion to glass. However, PETN as sheet explosive and plasticized RDX (C-4), showed very little potential to contaminate surfaces, either by spillage or adhesion to glass.     

Application of LC−QTOF/MS for the validation and determination of organic explosive residues on Ionscan® swabs

The identification and confirmation of trace explosive residues along with potential precursors and degradation products require a comprehensive laboratory analysis procedure. This study presents the determination of organic explosives consisting of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), 2,4,6,N-tetranitro-N-methylaniline (Tetryl), 1,3,5-trinitrobenzene (1,3,5-TNB) and pentaerythritol tetranitrate (PETN) by a high-resolution liquid chromatography quadrupole time-of-flight mass spectrometry (LC−QTOF/MS). The qualitative information including retention time, collision energy, precursor ions, and characteristic fragmentation pattern of each explosive were collected using an atmospheric pressure chemical ionization (APCI) in negative ion mode. The separation efficiency among five compounds was greatly achieved in this study. Four real explosive samples consisting of TNT, RDX, PETN and Tetryl and 12 Ionscan® quality control swabs from the Royal Thai Army were also tested to validate and verify the viability of the GC–MS method used to validate results from an Ionscan® system. The results showed that LC−QTOF/MS is a powerful technique for the identification and confirmation of thermally unstable organic explosives on Ionscan® swabs compared to a conventional GC−MS technique.     

有机爆炸物的现场非介入性检测——顶空固相微萃取一真空气相色谱质谱法

本文考察了顶空固相微萃取在有机爆炸物现场非介入性检测中的适用性。由固相萃取（SPME）纤维头吸附的有机爆炸物用真空气相色谱一质谱联用仪进行检测。该方法所需的洗脱温度低,色谱分离时间短。SPME适用于提取蒸汽压不低于2．4,6-三硝基甲苯（TNT）的挥发性和半挥发性有机爆炸物,如较易挥发且不稳定的化合物三过氧化三丙酮（TATP）的非介入性检测就可以应用该方法。本研究使用静态顶空,尽可能地减少顶空体积,实现了较高的灵敏度。在现场,SPME方法的灵敏度受环境温度的影响较大：由于样品的蒸汽压未达到平衡,在固定顶空体积和萃取时间的条件下,SPME纤维头萃取的样品总量随温度的提高而增加。在有合适容器的情况下SPME纤维头上萃取的样品在取样3天后仍然能顺利检测。     

Visual detection of trace nitroaromatic explosive residue using photoluminescent metallole-containing polymers

The detection of trace explosives is important for forensic, military, and homeland security applications. Detection of widely used nitroaromatic explosives (trinitrotoluene [TNT], 2,4-dinitrotoluene [DNT], picric acid [PA]) was carried out using photoluminescent metallole-containing polymers. The method of detection is through the quenching of fluorescence of thin films of the polymer, prepared by spray coating organic solutions of the polymer, by the explosive analyte. Visual quenching of luminescence (lambda(em) approximately 400-510 nm) in the presence of the explosive is seen immediately upon illumination with near-UV light (lambda(ex)=360 nm). Detection limits were observed to be as low as 5 ng for TNT, 20 ng for DNT, and 5 ng for PA. In addition, experiments with normal production line explosives and their components show that this technology is also able to detect composition B, Pyrodex, and nitromethane. This method offers a convenient and sensitive method of detection of trace nitroaromatic explosive residue.     

Destruction of Peroxide Explosives

Abstract:  Chemicals containing multiple peroxide functionalities, such as triacetone triperoxide (TATP), diacetone diperoxide (DADP), or hexamethylene triperoxide diamine (HMTD), can be explosive. They are impractical and are not used by legitimate military groups because they are shock and heat sensitive compared to military explosives. They are attractive to terrorists because synthesis is straightforward, requiring only a few easily obtained ingredients. Physical removal of these synthesis products is highly hazardous. This paper discusses methods to degrade peroxide explosives chemically, at room temperature. A number of mixtures containing metals (e.g., zinc, copper) and metal salts (e.g., zinc sulfate, copper chloride) were found effective, some capable of destroying TATP solutions in a few hours. Strong acids proved useful against solid peroxide materials; however, on a 1 g scale, addition of concentrated sulfuric acid caused TATP to detonate. Thus, this technique should only be used to destroy small-laboratory quantities.     

The natural sampling of airborne trace signals from explosives concealed upon the human body.

An experimental study of the natural sampling of trace signals from explosives concealed upon the human body was performed by taking proper account of the thermal behavior of the air surrounding the human body and the particles therein. Experiments were conducted in a dispersal chamber to identify variables affecting the detectibility of concealed RDX and TNT patches. Movement by human volunteers was found to enhance the available explosive trace signal above a baseline level. Clothing blocked some of this movement-generated trace signal. The detected signal levels were also found to vary significantly from volunteer to volunteer, indicating that human variability is an issue in explosive trace detection. Further, under the conditions studied here, the detectibility of RDX and TNT was dependent upon the efficient sampling of contaminated particulate matter, not the vapor phase. The present results are now being applied to the design of a practical, nonintrusive trace detection portal for aviation security screening and related applications.     

Evaluation of vapor profiles of explosives over time using ATASS (Automated Training Aid Simulation using SPME)

Despite numerous instrumental achievements, canines are still considered the most effective field method for explosive detection. However, due to strict explosive regulations and safety requirements, it can be a challenge for agencies with "bomb dogs" to train using neat explosive materials. This establishes a need for non-explosive canine training aids with the same volatile component profiles as the explosives that they represent. In order to compare mimic materials to their explosive counterparts, a technique must be established that not only allows for identification of volatile compounds but also can monitor changes in the headspace profile over time with respect to time and temperature. The Automated Training Aid Simulation using SPME (or ATASS) was developed for that purpose. As described, ATASS was used to observe changes in the volatile profile of three explosives (Composition C-4, 2,4-dinitrotoluene (DNT), and triacetone triperoxide (TATP)) and respective prototype training materials (0.1% by mass C-4, 1% by mass 2,4-DNT, and 1% by mass TATP). Samples were prepared in vials and metal tins within a gallon (≈ 3785 mL) paint can to simulate common field techniques for canine training. Monitoring these materials in real time provides a better understanding of the major volatile components present and how the relative abundances of these components can change over time. The results presented indicate that ATASS successfully allows for a sufficient comparison between explosive and non-explosive training materials.     

The Identification of Chlorinated Acetones in Analyses of Aged Triacetone Triperoxide (TATP)

The organic peroxide explosive triacetone triperoxide (TATP) is regularly encountered by law enforcement agents in various stages of its production, storage, or usage. In a previous study, it has been demonstrated that isolated, rigorously purified, TATP may degrade to form a series of chlorinated acetones when directly treated with excess concentrated hydrochloric acid. The current study extends this work to examine whether this phenomenon may be measured during the more feasible scenario of aging of rudimentarily purified TATP contaminated with trace reaction mixture. It was demonstrated that solid-phase microextraction gas chromatography/mass spectrometry analyses of aged TATP that was synthesized utilizing hydrochloric acid catalyst may identify the presence of the degradation products chloroacetone and 1,1-dichloroacetone. Upon aging of TATP synthesized utilizing either sulfuric or nitric acid catalyst, no acid specific degradation products could be identified. These findings may be exploited by forensic chemists in the analyses of TATP samples.     

Sulfuric, hydrochloric, and nitric acid-catalyzed triacetone triperoxide (TATP) reaction mixtures: an aging study

The organic peroxide explosive triacetone triperoxide (TATP) is regularly encountered by law enforcement agents in various stages of its production. This study utilizes solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) to examine sulfuric acid-, hydrochloric acid-, and nitric acid-catalyzed TATP syntheses during the initial 24 h of these reactions at low temperatures (5-9°C). Additionally, aging of the reaction mixtures was examined at both low and ambient temperatures (19-21°C) for a further 9 days. For each experiment, TATP could be readily identified in the headspace above the reaction mixture 1 h subsequent to the combination of reagents; at 24 h, TATP and diacetone diperoxide (DADP) were prominent. TATP degraded more rapidly than DADP. Additionally, chlorinated acetones chloroacetone and 1,1,-dichloroacetone were identified in the headspace above the hydrochloric acid-catalyzed TATP reaction mixture. These were not present when the catalyst was sulfuric acid or nitric acid.     

Cyclic Pentanone Peroxide: Sensitiveness and Suitability as a Model for Triacetone Triperoxide

Research to counter the threat of organic peroxides such as triacetone triperoxide (TATP) is at times hampered by their inherent extreme sensitiveness and volatility. This work describes an approach to lowering some risks associated with the handling of TATP in the laboratory through the use of an analog species, tripentanone triperoxide (TPTP). Sensitiveness has been tested via standard methods. GCMS analysis has shown that TPTP degrades via similar mechanisms to TATP under a range of conditions. Slight differences in product composition were traced to side reactions which may also affect impurities present in homemade TATP synthesis. A pilot field trial was conducted to evaluate TPTP as a substitute for TATP in explosive detection dog (EDD) scent training. The degradation studies have yielded insights into the complexities of the acidic degradation of cyclic peroxides with potential forensic application, and TPTP's inadequacy as a TATP pseudoscent is a valuable example of the limitations of such training aids.     

Trace analysis of peroxide explosives by high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS/MS) for forensic applications

An HPLC-APCI-MS(/MS) method for the (trace) analysis of the most commonly encountered peroxide explosives, hexamethylenetriperoxidediamine (HMTD) and triacetonetriperoxide (TATP), has been developed. With this method, HMTD and TATP have been analyzed in the same run. (Pseudo-)molecular ions of these peroxides have been obtained as base peak under the same condition. A series of product ions was produced from these pseudo-molecular ions ([HMTD - 1]+ and [TATP + NH4]+) in the MS/MS analysis. We also pioneered in showing that a TATP molecular ion [TATP + H]+ can be observed with HPLC-MS/MS. The limit of detection for HMTD and TATP was 0.26 and 3.3 ng, respectively, on column by HPLC-MS in the Full Scan mode and 0.08 and 0.8, respectively, by HPLC-APCI-MS/MS in Selected Reaction Monitoring (single mass unit) mode. The method presented has been applied successfully for the identification of peroxides in the bulk solid state (powder sample), as well as in post-blast extracts originating from a forensic case. For the post-blast extracts, the use of tandem MS has been shown clearly to be of crucial importance for the identification and detection of the peroxide explosives.     

Detection of nitro-organic and peroxide explosives in latent fingermarks by DART- and SALDI-TOF-mass spectrometry

The ability of two mass spectrometric methods, surface-assisted laser desorption/ionization-time of flight-mass spectrometry (SALDI-TOF-MS) and direct analysis in real time (DART-MS), to detect the presence of seven common explosives (six nitro-organic- and one peroxide-type) in spiked latent fingermarks has been examined. It was found that each explosive could be detected with nanogram sensitivity for marks resulting from direct finger contact with a glass probe by DART-MS or onto stainless steel target plates using SALDI-TOF-MS for marks pre-dusted with one type of commercial black magnetic powder. These explosives also could be detected in latent marks lifted from six common surfaces (paper, plastic bag, metal drinks can, wood laminate, adhesive tape and white ceramic tile) whereas no explosive could be detected in equivalent pre-dusted marks on the surface of a commercial lifting tape by the DART-MS method due to high background interference from the tape material. The presence of TNT and Tetryl could be detected in pre-dusted latent fingermarks on a commercial lifting tape for up to 29 days sealed and stored under ambient conditions.     

Characterization of an odor permeable membrane device for the storage of explosives and use as canine training aids

The storage and use of explosives is regulated at the state and federal level, with a particular focus on physical security and rigorous accounting of the explosive inventory. For those working with explosives for the training and testing of explosive-detecting canines, cross-contamination is an important concern. Hence, explosives intended for use with canine teams must be placed into secondary storage containers that are new, clean, and airtight. A variety of containers meet these requirements and include screw-top glass jars (e.g., mason jars). However, an additional need from the explosive-detecting canine community is secondary containers that can also be used as training aids whereby the volatiles emitted by explosives are emitted in a predictable and stable manner. Currently, a generally accepted method for the storage of explosives and controlled emission of explosive vapor for canine detection does not exist. Ideally, such containers should allow odor to escape from the training aid but block external contaminates such as particulates or other volatiles. One method in use places the explosive inside a permeable cotton bag when in use for training and then stores the cotton bag inside an impermeable nylon bag for long-term storage. This paper describes the testing of an odor permeable membrane device (OPMD) as a new way to store and deploy training aids. We measured the evaporation rate and flux of various liquid explosives and volatile compounds that have been identified in the headspace of actual explosives. OPMDs were used in addition to traditional storage containers to monitor the contamination and degradation of 14 explosives used as canine training aids. Explosives were stored individually using traditional storage bags or inside an OPMD at two locations, one of which actively used the training aids. Samples from each storage type at both locations were collected at 0, 3, 6, and 9 months and analyzed using Fourier Transform Infrared (FTIR) Spectroscopy and Gas Chromatography–Mass Spectrometry (GC–MS) with Solid-Phase Microextraction (SPME). FTIR analyses showed no signs of degradation. GC–MS identified cross-contamination from ethylene glycol dinitrate (EGDN) and/or 2,3-dimethyl-2,3-dinitrobutane (DMNB) across almost all samples regardless of storage condition. The contamination was found to be higher among training aids that were stored in traditional ways and that were in active use by canine teams.     

Surface-sampling and analysis of TATP by swabbing and gas chromatography/mass spectrometry

The method of sample recovery for trace detection and identification of explosives plays a critical role in several criminal investigations. After bombing, there can be difficulties in sending big objects to a laboratory for analysis. Traces can also be searched for on large surfaces, on hands of suspects or on surfaces where the explosive was placed during preparatory phases (e.g. places where an IED was assembled, vehicles used for transportation, etc.).In this work, triacetone triperoxide (TATP) was synthesized from commercial precursors following reported methods. Several portions of about 6 mg of TATP were then spread on different surfaces (e.g. floors, tables, etc.) or used in handling tests. Three different swabbing systems were used: a commercial swab, pre-wetted with propan-2-ol (isopropanol) and water (7:3), dry paper swabs, and cotton swabs wetted with propan-2-ol. Paper and commercial swabs were also used to sample a metal plate, where a small charge of about 4 g of TATP was detonated. Swabs were sealed in small glass jars with screw caps and Parafilm^® M and sent to the laboratory for analysis. Swabs were extracted and analysed several weeks later by gas chromatography/mass spectrometry. All the three systems gave positive results, but wetted swabs collected higher amounts of TATP. The developed procedure showed its suitability for use in real cases, allowing TATP detection in several simulations, including a situation in which people wash their hands after handling the explosive.     

Rapid screening of selected organic explosives by high performance liquid chromatography using reversed-phase monolithic columns

This study presents the rapid screening of various high grade explosives by high performance liquid chromatography (HPLC) with monolithic stationary phases. Two gradient methods were developed, the first for quantitative analysis of eleven explosives: HMX; RDX; Tetryl; TNT; 2,3-DNT; 2,6-DNT; 3,4-DNT; 2-NT; 3-NT; 4-NT; and PETN in under 14 min. The second method separated seven explosives in under two min and is suitable for rapid screening to determine the presence of specific and/or class of explosive. The rapid screening methods were successfully applied to soils spiked with known amounts of target explosives. This technology showed excellent potential for forensic explosives detection and analysis.