Glycol Dinitrate Research Articles

Effect of membrane properties on the odor emanating from training aids for explosive-detecting canines.

Canines are widely used for real-time detection of explosives and have proven to be on par with instrumental methods. Canines are thought to rely largely upon detection of volatile chemical constituents of the explosives, though not necessarily the explosive itself. Hence, it is crucial to understand the odor available to them as generated by training aids. Previous studies have established that the Training Aid Delivery Device (TADD) developed by SciK9 is a reliable training aid that reduces cross-contamination and doubles as a storage device. A TADD comprises a standardized container, a synthetic membrane, a membrane holder, and a lid. In the work presented, activated charcoal strips were placed above and below the TADD membrane to determine the relative amounts of volatiles emitted by dynamite (i.e., ethylene glycol dinitrate (EGDN) and trinitroglycerin (NG)). The strips were eluted and the extracts tested using gas chromatography-mass spectrometry in negative ion chemical ionization mode. A series of t-tests at 95% confidence level were performed to determine any differences in vapor composition above and below the membranes. Nine synthetic membranes and six glass fiber membranes were tested in this study. It was expected that the relative concentration of volatiles would remain the same on both sides of the membrane; however, selective removal of nitroglycerin by some membranes was observed. Synthetic membranes with larger pore sizes showed no alteration in the vapor composition. Both synthetic and glass fiber membranes did not show a significant change in relative concentration of the other volatile compound in dynamite, i.e., EGDN. Out of all the membranes tested, three synthetic membranes and four glass fiber membranes showed selective alteration in odor availability of nitroglycerin in dynamite. For training purposes, membranes that do not alter the vapor composition should be used in the training aid.

Highly Scalable and Inherently Safer Preparation of Di, Tri and Tetra Nitrate Esters Using Continuous Flow Chemistry.

Nitrate esters are important organic compounds having wide application in energetic materials, medicines and fuel additives. They are synthesized through nitration of aliphatic polyols. But the process safety challenges associated with nitration reaction makes the production process complicated and economically unviable. Herein, we have developed a continuous flow process wherein polyol and nitric acid are reacted in a microreactor to produce nitrate ester continuously. Our developed process is inherently safer and efficient. The process was optimized for industrially important nitrate esters containing two, three and four nitro groups. Substrates include glycol dinitrates: 1,2-propylene glycol dinitrate (PGDN), ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (DEGDN), triethylene glycol dinitrate (TEGDN); trinitrates: trimethylolethane trinitrate (TMETN), 1,2,4-butanetriol trinitrate (BTTN); and tetranitrates: erythritol tetranitrate (ETN). The optimized process for each molecule provided yield >90 % in a short residence time of 1 min corresponding to a space time yield of >18 g/h/mL of reactor volume.

Surface denitration structure on dynamic combustion performance and muzzle flame of mixed nitrate gun propellant

AbstractThe gun propellant is an inaccessible energy and fuel for projectile to achieve destructive capability in a weapon system. Nitrocellulose/nitroglycerine/triethylene glycol dinitrate(NC/NG/TEGDN) based gun propellant with higher energy level than single‐based gun propellant can meet the demands of modern warfare. Currently, deterring strategy is commonly used to improve the combustion progressivity of NC/NG/TEGDN based gun propellant, together with aggravating the harmful emission phenomena such as muzzle smoke and flame. Therefore, it is essential to design and fabricate NC/NG/TEGDN based gun propellant with both good combustion progressivity and low characteristic signal. In this work, a gradiently denitrated NC/NG/TEGDN based gun propellant was successfully prepared by denitration strategy, whose structure was confirmed by FT‐IR, Raman and SEM. Here, closed bomb vessel test and interior ballistic test were conducted. The results showed that the gradiently denitrated NC/NG/TEGDN based gun propellant exhibited better combustion progressivity and interior ballistic performance than raw gun propellant, and these properties can be controlled by modulating the degree of denitration. Meanwhile, the change laws of the muzzle smoke and flame of the gradiently denitrated NC/NG/TEGDN based gun propellant were investigated by the smoke box method and high‐speed photography. Furthermore, a lower characteristic signal for the gradiently denitrated NC/NG/TEGDN based gun propellant was found compared to the deterred gun propellant by theoretical calculations. This work provides a new idea for preparing and applying a gun propellant with excellent comprehensive performance, including high energy, good combustion progressivity and low characteristic signal.

Determination of Ethylene Glycol Dinitrate in Environmental and Forensic Water Samples Using Microextraction by Packed Sorbent Followed by Gas Chromatography

Ethylene glycol dinitrate (EGDN) is a liquid nitrate ester, a secondary explosive. In the past, it was used as an explosive ingredient in dynamite along with nitroglycerine. Due to its various applications, the reliable detection of EGDN in the environment is a key issue for both forensic and environmental applications. In these areas, sensitive and reliable methods for determining the concentration of nitro compounds are needed. Microextraction by packed sorbent (MEPS) is an innovative approach to green technology in the sample preparation field. Compared to conventional solid-phase extraction (SPE), MEPS uses a smaller sample volume and can be easily combined with various chromatographic techniques. An important benefit is the reduction of sorbent amount and up to 100-times repeatable use compared to disposable SPE columns, thus reducing the costs of analysis as well as waste production. Optimal extraction parameters for isolating EGDN from water, e.g., 30 µL of toluene as extraction agent, working in one cycle and in draw/discard mode, were selected. Method validation was performed, obtaining a limit of detection and a limit of quantification of 0.45 pg/μL and 1.34 pg/μL, respectively. Accuracy in terms of recovery rates was evaluated over a wide concentration range, obtaining values from 83.7 to 90.0%. The satisfactory linearity expressed by the coefficient of determination was 0.9914. A matrix factor of −9.3% indicates a weak matrix effect. The application to real environmental water samples and a forensic post-blast wash water sample was realized. EGDN detection in the post-blast samples provides valuable information for forensic technicians.

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 9months 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.

Crystal Structures of the Commonly Used Plasticizers Ethylene Glycol Dinitrate, Diethylene Glycol Dinitrate, and Triethylene Glycol Dinitrate─Characterization and Discussion of Their Structural Behavior

Ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (DEGDN), and triethylene glycol dinitrate (TEGDN) are used as plasticizers in propellant mixtures and have been known for more than 100 years. Despite the industrial application and the long history of these compounds, the crystal structures of all three compounds, which are liquids at room temperature, have not been determined. Therefore, in this work, the crystal structures were examined by low-temperature X-ray diffraction, and thus, the bonding properties and crystal packing in the solid state could be compared and discussed for the first time. Furthermore, the compounds were characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy. The thermal properties were investigated by DTA (differential thermal analysis) measurements, and the experimental vapor pressures were measured with the chromatography-assisted transpiration method. The densities at room temperature (for the liquids) were measured by gas pycnometry, and the energetic properties were calculated using the EXPLO5 code. Moreover, a more in-depth analysis of the different sensitivities through discussion of the Hirshfeld surfaces, created based on their crystal structures, was performed to compare their sensitivities in the solid state.

Forensic science deals with safety armour during warfare explosives

Forensic analysis of explosives includes analysis of post-explosion residues, and detection and identification of traces of explosives on suspects’ hands, on clothing, and on other related items. Preliminary field tests may be used for screening the debris on the explosion site. They include commercially available explosive vapor detectors and chemical color tests. Like post-explosion residues, personal items suspected to contain traces of explosives and hand-swabs, are often heavily contaminated. It is therefore of major importance that the analytical procedures have to include good screening, clean-up, and extraction methods. The main explosives dealt with in this chapter include nitroaromatic explosives, such as 2,4,6-trinitrotoluene (TNT) and 2,4,6, N-tetranitro-N-methyl aniline (tetryl), nitrate esters, such as ethylene glycol dinitrate (EGDN), glycerol trinitrate (nitroglycerin, NG), and pentaerythritol tetranitrate (PETN), and nitramine explosives, such as 1,3,5- trinitro-1,3,5-triazacyclohexane, (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), as well as mixtures containing one or more of these explosives. Additional explosives include triacetone triperoxide (TATP) and ammonium nitrate (AN), NH4NO3.

Development and validation of a new RP-HPLC method for organic explosive compounds.

A new RP-HPLC method was developed and validated to achieve the separation and quantification of the organic explosive compounds such as pentaerythritol tetranitrate (PETN), 1-methyl-2,4,6-trinitro toluen (TNT), picric acid, 1,3,5,7-tetrazocine (HMX), cyclorimethylenetrinitramine (RDX), 2,4,6 Tri nitro phenyl methyl nitramine (Tetryl), 1-methyl-2,4-dinitro toluen (DNT), ethylene glycol dinitrate (EGDN), and trinitroglycerine (TNG) in this study. The mobile phase composition (IPA percentage in water) and the flow rate was optimized for the separation of the organic explosive compounds. Theoretical plate number (N), capacity factor (k'), resolution (Rs) were used to determine the optimum chromatographic conditions. The most favorable conditions were detected as 22% IPA in water, a flow rate of 1.7 mL/min. Under optimum chromatographic conditions, separation was completed within 18 min. The linear ranges were 6.5-100 and 10-0.625 mg/L (R2 = 0.998-0.999) for investigated explosives. Mean recoveries were found to be in the range of 95.3%-103.3%. LOD and LOQ were ranged between 0.09-1.32 mg/L and 0.31-4.42 mg/L, respectively, for investigated explosives. The obtained results showed that the new method was very suitable for the separation of the resolution of organic explosive compounds with C18 columns. TNT and RDX seized from terrorists were found to be in 372.99 mg/L and 79.55 mg/L, respectively.

Predicting vapour transport from semi-volatile organic compounds concealed within permeable packaging

The vapour concentration present in enclosed spaces containing concealed semi-volatile organic compounds (SVOCs), such as explosives, is difficult to measure experimentally. Therefore, mathematical models play a key role in understanding the transport of these materials. Vapour transport has previously been modelled in a range of environments, from small emission cells to whole rooms, using both analytical and numerical approaches. These models typically include either a well-mixed air volume or a simple sorption model. This work has been extended by including a multi-layer vapour sorption/permeation model within a computational fluid dynamics (CFD) framework. This allows for vapour source terms from items concealed within permeable packaging to be considered. The CFD based permeation model includes sorption/desorption, using a linear isotherm at inner and outer surfaces and a blended wall function to account for the effects of near-wall turbulence. The model has been validated for the explosive SVOC, ethylene glycol dinitrate (EGDN). The model has been used to show how vapour concentrations around a cardboard box containing a SVOC vary when some of the key input parameters are changed. Changing the vapour source from EGDN to the much lower vapour pressure trinitrotoluene (TNT), had a significant effect, as expected, and this was most pronounced early on due to the difference in permeation lag times for the two materials. Conversely, changing the type of cardboard had only a small effect on the concentrations. This type of modelling approach can now be used to study a wide range of SVOC transport problems which would not previously have been possible.

A selective and stepwise aggregation of a new fluorescent probe for dinitrate explosive differentiation by self-adaptive host-guest interaction

Nitrate explosive is hard to detect due to lack of aromatic ring and weak interaction with fluorescence probe. More challenging is even to differentiate the dinitrates with multiple nitrate explosives based on photo induced electron transfer or aggregation caused fluorescence change mechanism. A highly selective dinitrate explosive probe was designed based on a new strategy ¾ stepwise aggregation of multiple anchored fluorene dimer 8Py-2F . Compared with its monomer counterpart 2Py-F , 8Py-2F showed a selective and stepwise fluorescence quenching to dinitrate explosives—ethylene glycol (EGDN) and triethylene glycol dinitrate (TEGDN). The limits of detection (LODs) are 2.72 μM for TEGDN and 0.46 μM for EGDN, which is three orders of magnitude lower than those of 2Py-F . The stepwise quenching process is well matched with the stepwise aggregation process as evidence by scanning electron microscopy (SEM). Nuclear magnetic resonance (NMR) and quantum chemical calculation proved the interaction force between the dinitrate and 8Py-2F is hydron bonding interaction, and interaction distance is far less than that of the multiple nitrates coming from the flexibility of the chain and steric hinderance, which resulted in a self-adaptive interaction and higher selectivity. The new strategy is beneficial for the differentiation of the chemicals with similar energy level which is difficult to realize via other method, and the new method provides fluorometric probe for dinitrate explosive detection and makes it an ideal candidate for chemical detection and analysis in public safety and environmental monitoring.

Vapor Pressure of Linear Nitrate Esters Determined by Transpiration Method in Combination with VO‐GC/MS

AbstractGas phase detection of explosives is an ongoing trend in the detection sciences. The conception of gas phase detection devices requires knowledge about gas phase concentration of the target analytes. Nitrate esters are well performing explosives with a high potential for misuse in improvised explosive devices that need to be detected at vulnerable infrastructures. With respect to this the six nitrate esters, ethyl nitrate (1), ethylene glycol dinitrate (2), glycerol trinitrate (3), meso‐erythritol tetranitrate (4), d‐mannitol hexanitrate (5) and pentaerythritol tetranitrate (6) were investigated in terms of detectability by vacuum outlet‐GC/MS as potential components in improvised explosive devices. All compounds besides 5 could be detected using vacuum outlet GC/MS and their limits of detection were determined according to DIN 32645 : 2008. The vapor pressure of 2–4 was measured using the transpiration method. It was observed that the introduction of a CHONO2 unit lowers the vapor pressure of the nitrate esters by about two orders of magnitude. For compound 4 the saturation concentration (73 ng L−1) was compared with a vapor pressure based estimation of its concentration in diffusion equilibrium (0.385 pg L−1).

Generating highly specific spectra and identifying thermal decomposition products via Gas Chromatography / Vacuum Ultraviolet Spectroscopy (GC/VUV): Application to nitrate ester explosives

Gas chromatography/mass spectrometry (GC/MS) is a "workhorse" instrument for chemical analysis, but it can be limited in its ability to differentiate structurally similar compounds. The coupling of GC to vacuum ultraviolet (VUV) spectroscopy is a recently developed technique with the potential for increased detection specificity. To date, GC/VUV has been demonstrated in the analysis of volatile organic compounds, petroleum products, aroma compounds, pharmaceuticals, illegal drugs, and lipids. This paper is the first to report on the utility of GC/VUV for explosives analysis in general, and the first to report on thermal degradation within the VUV cell and its analytical utility. The general figures of merit and performance of GC/VUV were evaluated with authentic standards of nitrate ester explosives (e.g., nitroglycerine (NG), ethylene glycol dinitrate (EGDN), pentaerythritol tetranitrate (PETN), and erythritol tetranitrate (ETN)). In addition, the explosive analytes were thermally degraded in the VUV cell, yielding reproducible, complex and characteristic mixtures of gas phase products (e.g., nitric oxide, carbon monoxide, and formaldehyde). The relative amounts of the degradation products were estimated via spectral subtraction of library spectra. Lastly, GC/VUV was used to analyze milligram quantities of intact and burned samples of double-base smokeless powders containing nitroglycerine, diphenylamine, ethyl centralite, and dibutylphthalate

Application of a co-polymeric solid phase extraction cartridge to residues containing nitro-organic explosives

A validated solid phase extraction (SPE) cleanup procedure utilizing Bond Elut NEXUS co-polymeric cartridges has been applied to soil and swab samples containing pre- and post-blast residues of nitro-organic explosives. In addition, simulated samples were also processed by SPE to evaluate matrix rejection and interferences. The matrices were extracted with acetone, diluted with deionized water, and processed by SPE. The final extracts were then analyzed by gas chromatography with electron capture detection (GC/ECD) to screen for the compounds of interest, which included ethylene glycol dinitrate (EGDN), dimethyl dinitrobutane (DMDNB), 4-nitrotoluene (4-NT), nitroglycerin (NG), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), pentaerythritol tetra-nitrate (PETN), cyclotrimethylene trinitramine (RDX), 2,4,6-trinitrophenylmethylnitramine (tetryl), cyclotetra-methylene tetranitramine (HMX), erythritol tetranitrate (ETN), and cyclotrimethylene trinitrosoamine (R-salt). The expected explosives were detected in 97% of cases after processing through SPE and analysis by GC/ECD. Approximately one-third of the samples that screened positive by ECD were subjected to confirmation testing by gas or liquid chromatography/mass spectrometry (GC/MS or LC/MS). The results from these matrices were compared to results obtained by syringe filtration. SPE produced equal or better results than syringe filtration in both the ECD screening and MS confirmation tests, including the ability to detect higher signals for more explosives in the post-blast residue samples. The confirmation results also show that all of the expected explosives could be confirmed after processing by SPE, whereas only 83% of them were confirmed after syringe filtration. This study demonstrates the successful application of a validated method to the cleanup of organic explosive residues in complex matrices.

Sorbent Film-Coated Passive Samplers for Explosives Vapour Detection Part B: Deployment in Semi-Operational Environments and Alternative Applications

The application of new sorbent-film coated passive samplers for capture of bulk commercial and military explosives vapours in operationally relevant spaces such as luggage, rooms, vehicles and shipping containers is presented. Samplers were easily integrated with in-service detection technologies with little/no sample preparation required. Ethylene glycol dinitrate (EGDN) was detected within 4 h in a container holding a suitcase packed with 0.2 kg Perunit 28E. Within a 22,000 dm3 room, 1 kg of concealed Seguridad was detected within 24 h and in an adjoining room within 7 days. Exposed samplers also successfully captured components of 1 kg TNT after 72 h and 1 kg concealed Perunit 28E after 6 h in both a furnished room and a large, partially filled shipping container. For the latter, samplers captured detectable residues outside the container after 24 h and were stable during wet weather for 72 h. A one-week trial at three operationally relevant venues including a university, a theatre and a government building revealed a nuisance positive rate of <1.4% (n = 72). Finally, two alternative applications are presented for extraction of liquid samples and use a particulate contact swab showing flexibility for a range of different search activities.

Trace explosives sensor testbed (TESTbed).

A novel vapor delivery testbed, referred to as the Trace Explosives Sensor Testbed, or TESTbed, is demonstrated that is amenable to both high- and low-volatility explosives vapors including nitromethane, nitroglycerine, ethylene glycol dinitrate, triacetone triperoxide, 2,4,6-trinitrotoluene, pentaerythritol tetranitrate, and hexahydro-1,3,5-trinitro-1,3,5-triazine. The TESTbed incorporates a six-port dual-line manifold system allowing for rapid actuation between a dedicated clean air source and a trace explosives vapor source. Explosives and explosives-related vapors can be sourced through a number of means including gas cylinders, permeation tube ovens, dynamic headspace chambers, and a Pneumatically Modulated Liquid Delivery System coupled to a perfluoroalkoxy total-consumption microflow nebulizer. Key features of the TESTbed include continuous and pulseless control of trace vapor concentrations with wide dynamic range of concentration generation, six sampling ports with reproducible vapor profile outputs, limited low-volatility explosives adsorption to the manifold surface, temperature and humidity control of the vapor stream, and a graphical user interface for system operation and testing protocol implementation.

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.

Atmospheric pressure chemical ionization of explosives induced by soft X-radiation in ion mobility spectrometry: mass spectrometric investigation of the ionization reactions of drift gasses, dopants and alkyl nitrates.

A promising replacement for the radioactive sources commonly encountered in ion mobility spectrometers is a miniaturized, energy-efficient photoionization source that produce the reactant ions via soft X-radiation (2.8 keV). In order to successfully apply the photoionization source, it is imperative to know the spectrum of reactant ions and the subsequent ionization reactions leading to the detection of analytes. To that end, an ionization chamber based on the photoionization source that reproduces the ionization processes in the ion mobility spectrometer and facilitates efficient transfer of the product ions into a mass spectrometer was developed. Photoionization of pure gasses and gas mixtures containing air, N2 , CO2 and N2 O and the dopant CH2 Cl2 is discussed. The main product ions of photoionization are identified and compared with the spectrum of reactant ions formed by radioactive and corona discharge sources on the basis of literature data. The results suggest that photoionization by soft X-radiation in the negative mode is more selective than the other sources. In air, adduct ions of O2- with H2 O and CO2 were exclusively detected. Traces of CO2 impact the formation of adduct ions of O2- and Cl- (upon addition of dopant) and are capable of suppressing them almost completely at high CO2 concentrations. Additionally, the ionization products of four alkyl nitrates (ethylene glycol dinitrate, nitroglycerin, erythritol tetranitrate and pentaerythritol tetranitrate) formed by atmospheric pressure chemical ionization induced by X-ray photoionization in different gasses (air, N2 and N2 O) and dopants (CH2 Cl2 , C2 H5 Br and CH3 I) are investigated. The experimental studies are complemented by density functional theory calculations of the most important adduct ions of the alkyl nitrates (M) used for their spectrometric identification. In addition to the adduct ions [M + NO3 ]- and [M + Cl]- , adduct ions such as [M + N2 O2 ]- , [M + Br]- and [M + I]- were detected, and their gas-phase structures and energetics are investigated by density functional theory calculations. Copyright © 2016 John Wiley & Sons, Ltd.

Infrared spectroscopy of ICAO taggants

The IR absorption spectra of the ICAO taggants, ethylene glycol dinitrate (EGDN), o-mononitrotoluene (2-NT), p-mononitrotoluene (4-NT) and 2,3-dimethyl-2,3-dinitrobutane (DMDNB) in the vapor phase, are studied at room temperature over a wide frequency range (500–4000 cm–1). The pre-assignment of the observed vibrational bands was performed. Modern quantum-chemical methods are applied to calculate the equilibrium geometries of these molecules and the frequencies of their fundamental vibrations. For the most intense bands of 2-NT and 4-NT, the absorption cross sections are estimated. Based on analysis of current laser technology, it has been concluded that their use in conjunction with the available spectroscopic data makes it possible to reliably perform local and remote detection and identification of ICAO taggants in an open atmosphere in real time.

E-Smoking Liquids as Precursors for Liquid Nitroesters

Currently, E-smoking cigarettes are widely used and occur within all classes of society. This work investigated the use of E-smoking liquids for the synthesis of Nitroglycerin (NG) and 1,2-Propylene Glycol Dinitrate (PGDN), both considered as nitroester liquid high explosives. Two kinds of E-smoking liquids (10 mL) were investigated: nicotine free and with nicotine (10 mg/mL). Quantitative analysis of the glycerin and propylene glycol (PG) present in the E-smoking liquids was carried out by gas chromatography-mass spectrometry (GCMS), with calculation of the accuracy and precision parameters. The percentage of glycerin was (10-13 wt.%) and percentage of propylene glycol was (40-70 wt.%) The synthesis of pure NG and pure PGDN were performed with laboratory grade glycerin and propylene glycol and compared to the samples obtained from the E-smoking liquid. Differential Scanning Calorimetry (DSC) was used for the determination of the activation energy and the heat of decomposition for each synthesized explosive, using the Ozawa and Kissinger models. The brisance index was assessed by the witness plate test and compared with some conventional explosives (TNT and C4). Finally, the influence of nicotine (less than 2 wt.%) on the synthetic process and the detonic properties of the explosive mixture was studied.

Assessing a novel contact heater as a new method of recovering explosives traces from porous surfaces

It can be very challenging to recover explosives traces from porous surfaces, such as clothing and car seats, compared to non-porous surfaces. The contact heater has been developed as a novel instrument designed to recover explosives traces from porous surfaces. Samples are taken by heating and drawing air across a surface, with the air flowing through a sampling cartridge containing adsorbent polymer beads, which act to trap any recovered explosive material. Any collected explosive can then be eluted from this cartridge using a solvent, prior to analysis. This paper outlines work performed to evaluate the usefulness of the contact heater with regards to the recovery of explosives traces from porous materials. Ethylene glycol dinitrate (EGDN) and triacetone triperoxide (TATP) were chosen as two representative explosives for this study. Quantification was performed using GC–MS for EGDN and LC–MS/MS for TATP. Different sampling temperatures, sampling times and elution solvents were investigated. Recovery was trialled from leather, carpet and denim. Recoveries of up to 71% were obtained following optimisation. It was also possible to recover TATP from fabrics exposed to TATP vapour in a vapour-laden jar up to two hours after exposure. The contact heater therefore appears to be a very useful tool for the recovery of explosives traces from porous materials.