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Mitigation of the peroxide explosive threat, specifically triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), is a priority among the law enforcement community, as scientists and canine (K9) units are constantly working to improve detection. We propose the use of paper spray ionization–high-resolution mass spectrometry (PSI-HRMS) for detection of peroxide explosives in biological matrices. Occurrence of peroxide explosives and/or their metabolites in biological samples, obtained from urine or blood tests, give scientific evidence of peroxide explosives exposure. PSI-HRMS promote analysis of samples in situ by eliminating laborious sample preparation steps. However, it increases matrix background issues, which were overcome by the formation of multiple alkali metal adducts with the peroxide explosives. Multiple ion formation increases confidence when identifying these peroxide explosives in direct sample analysis. Our previous work examined aspects of TATP metabolism. Herein, we investigate the excretion of a TATP glucuronide conjugate in the urine of bomb-sniffing dogs and demonstrate its detection using PSI from the in vivo sample.

Triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are prominent explosive threats. Mitigation of peroxide explosives is a priority among the law enforcement community, with canine (K9) units being trained to recognise the scent of peroxide explosives. Herein, the metabolism, blood distribution, and toxicity of peroxide explosives are investigated.HMTD metabolism studies in liver microsomes identified two potential metabolites, tetramethylene diperoxide diamine alcohol aldehyde (TMDDAA) and tetramethylene peroxide diamine dialcohol dialdehyde (TMPDDD).Blood stability studies in dogs and humans showed that HMTD was rapidly degraded, whereas TATP remained for at least one week.Toxicity studies in dog and human hepatocytes indicated minimum cell death for both TATP and HMTD.

Encapsulation is proposed as a safer way of handling energetic materials. Different encapsulation methods for explosives, such as solvent evaporation, spray coating and supercritical carbon dioxide assisted encapsulation, were explored. Explosive training aids, where energetic materials, such as triacetone triperoxide (TATP), erythritol tetranitrate (ETN) and trinitrotoluene (TNT), are encapsulated in a polymer matrix were developed, followed by comprehensive quality control testing, including differential scanning calorimetry (DSC), thermogravimetric analysis-infrared spectroscopy (TGA-IR), gas chromatography-mass spectrometry (GC-MS), high-resolution mass spectrometry (HRMS) and sensitivity testing, and finally field approved by canine units trained on the pure explosive.

While exploring the synthesis pathway of HMTD, an unexpected new route for preparing HMTD was found through the reaction of formaldehyde, hydrogen peroxide, and ammonium hydroxide. The recovered HM...

Purpose Triacetone triperoxide (TATP) is a volatile but powerful explosive that appeals to terrorists due to its ease of synthesis from household items. For this reason, bomb squad, canine (K9) units, and scientists must work with this material to mitigate this threat. However, no information on the metabolism of TATP is available. Methods In vitro experiments using human liver microsomes and recombinant enzymes were performed on TATP and TATP-OH for metabolite identification and enzyme phenotyping. Enzyme kinetics for TATP hydroxylation were also investigated. Urine from laboratory personnel collected before and after working with TATP was analyzed for TATP and its metabolites. Results While experiments with flavin monooxygenases were inconclusive, those with recombinant cytochrome P450s (CYPs) strongly suggested that CYP2B6 was the principle enzyme responsible for TATP hydroxylation. TATP-O-glucuronide was also identified and incubations with recombinant uridine diphosphoglucuronosyltransferases (UGTs) indicated that UGT2B7 catalyzes this reaction. Michaelis–Menten kinetics were determined for TATP hydroxylation, with Km = 1.4 µM and Vmax = 8.7 nmol/min/nmol CYP2B6. TATP-O-glucuronide was present in the urine of all three volunteers after being exposed to TATP vapors showing good in vivo correlation to in vitro data. TATP and TATP-OH were not observed. Conclusions Since scientists working to characterize and detect TATP to prevent terrorist attacks are constantly exposed to this volatile compound, attention should be paid to its metabolism. This paper is the first to elucidate some exposure, metabolism and excretion of TATP in humans and to identify a marker of TATP exposure, TATP-O-glucuronide in urine.

Improvised explosive may be as primitive as a fuel and oxidizer mixture; yet not all fuel-oxidizer mixtures are explosive. Predicting explosive potential from laboratory-scale tests is desirable to...

Mitigation of the peroxide explosive threat, specifically triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), is a priority among the law enforcement community, as scientists and canine (K9) units are constantly working to improve detection. We propose the use of paper spray ionization-high-resolution mass spectrometry (PSI-HRMS) for detection of peroxide explosives in biological matrices. Occurrence of peroxide explosives and/or their metabolites in biological samples, obtained from urine or blood tests, give scientific evidence of peroxide explosives exposure. PSI-HRMS promote analysis of samples in situ by eliminating laborious sample preparation steps. However, it increases matrix background issues, which were overcome by the formation of multiple alkali metal adducts with the peroxide explosives. Multiple ion formation increases confidence when identifying these peroxide explosives in direct sample analysis. Our previous work examined aspects of TATP metabolism. Herein, we investigate the excretion of a TATP glucuronide conjugate in the urine of bomb-sniffing dogs and demonstrate its detection using PSI from the in vivo sample.

In this follow-up study the collaboration between two research groups from the USA and the Netherlands was continued to expand the framework of chemical attribution for the homemade explosive erythritol tetranitrate (ETN). Isotope ratio mass spectrometry (IRMS) analysis was performed to predict possible links between ETN samples and its precursors. Carbon, nitrogen, hydrogen and oxygen isotope ratios were determined for a wide variety of precursor sources and for ETN samples that were prepared with selected precursors. The stability of isotope ratios of ETN has been demonstrated for melt-cast samples and two-year old samples, which enables sample comparison of ETN in forensic casework independent of age and appearance. Erythritol and nitric acid (or nitrate salt) are the exclusive donor of carbon and nitrogen atoms in ETN, respectively, and robust linear relationships between precursor and the end-product were observed for these isotopes. This allowed for defining isotopic enrichment ranges for carbon and nitrogen that support the hypothesis that a given erythritol or nitrate precursor was used to synthesize a specific ETN batch. The hydrogen and oxygen atoms in ETN do not originate from one exclusive donor material, making linkage prediction more difficult. However, the large negative enrichments observed for both isotopes do provide powerful information to exclude suspected precursor materials as donor of ETN. Additionally, combing the isotopic data of all elements results in a higher discrimination power for ETN samples and its precursor materials. Combining the findings of our previously reported LC–MS analysis of ETN with this IRMS study is expected to increase the robustness of the forensic comparison even further. The partially nitrated impurities can provide insight on the synthesis conditions while the isotope data contain information on the raw materials used for the production of ETN.

This work is performed to determine if there is a potential for the accumulation and potential toxicity of triacetone triperoxide (TATP) in canines. Additional utility of this information may suggest human toxicity and possibly detection of biomarkers, metabolites or intact molecule of those using this material for nefarious reasons. Liquid chromatography/mass spectrometry of dog liver microsome (DLM) incubation samples of TATP was used to measure substrate depletion. Trapping of electrophilic products was performed using glutathione (GSH) and semicarbazide. Comparisons were made to free hydroperoxides found in methyl ethyl ketone peroxides (MEKP). The non-specific Km value of 2.2 μM and a Vmax of 1.1 nmol/min/mg of protein were determined. Canine recombinant cytochrome P450 (rCYP) 2B11 with human cytochrome b5 was found to catalyze the NADPH-dependent metabolism of TATP into its only phase I metabolite, hydroxy-TATP (TATP-OH). No secondary metabolite(s) or degraded products were detected or trapped from microsomal incubations. MEKP subjected to similar conditions was found to undergo significant metabolism, semicarbazide trapping and rapid oxidation of GSH to GSSG. The synthesized TATP-OH metabolite incubated in DLM progressed three times faster than TATP metabolism with no secondary metabolites found or trapped. TATP does not react as MEKP suggesting that TATP does not ring-open to form hydroperoxides. TATP and TATP-OH compete for the same enzyme, with TATP dominating this competition. Failure to detect additional metabolite(s) suggests they may be too small to detect by our system or bound covalently to a protein or polymer in the incubation reaction.

Finding a straightforward counter to infectious biological agents, such as Bacillus anthracis, is of great interest. We have found that a pyrotechnic mixture of iodate salts and aluminum is highly effective at producing heat and elemental iodine, both of which are considered as effective biocides. What is required is a general method of application. This paper outlines an approach to creating sprayable pyrotechnics. Polyurethane foams (energetic and non-energetic), nitrocellulose, and glycidyl azide polymer (GAP) have been applied as binders to pyrotechnic mixtures. Heat produced upon burning these formulations was quantified by bomb calorimetry, while iodine output was quantified by ultraviolet-visible spectroscopy (UV-Vis). The nitrocellulose-pyrotechnic formulation in acetone created a sprayable matrix, which dried to paint-like consistency. While the polyurethane-pyrotechnic was also sprayable, it was dried to a rigid, flammable foam. Properly formulated, all produced significant heat and iodi...

Our efforts to lower the detection limits of hexamethylene triperoxide diamine (HMTD) have uncovered previously unreported gas-phase reactions of primary and secondary amines with one of the six methylene carbons. The reaction occurs primarily in the atmospheric pressure chemical ionization (APCI) source and is similar to the behavior of alcohols with HMTD [1]. However, unlike alcohols, the amine reaction conserves the hydrogen peroxide on the intact product. Furthermore, with or without amines, HMTD is oxidized to tetramethylene diperoxide diamine dialdehyde (TMDDD) in a temperature-dependent fashion in the APCI source. Synthesized TMDDD forms very strong adducts (not products) to ammonium and amine ions in the electrospray ionization (ESI) source. Attempts to improve HMTD detection by generating TMDDD in the APCI source with post-column addition of amines were not successful. Signal intensity of the solvent related HMTD product in methanol, [HMTD+MeOH2–H2O2]+ (m/z 207.0975), was understandably related to the amount of methanol in the HMTD environment as it elutes into the source. With conditions optimized for this product, the detection of 100 pg on column was accomplished with a robust analysis of 300 pg (1.44 pmol) routinely performed on the Orbitrap mass spectrometers.

This paper considers a mariner under PDμ controller and analyses the effects of controller parameters on the yaw rate by using the Nomoto model. The Nomoto model describing the time evolution of the yaw rate of the steering dynamics of a mariner is reduced to an asymmetric Duffing oscillator with fractional order derivative. Under the approximation of calm water, the steady behavior of the mariner shows an “imperfect” supercritical pitchfork bifurcation. Region of safe behavior is identified and strategy to reduce the yaw rate by an appropriated selection of controller parameters are discussed. The frequency analysis of the mariner shows the prominence of hysteresis is reduced for small order of the fractional derivative as well as the amplitude of the yaw rate. Evidence of chaotic response is illustrated using robust chaotic indicators such as the Lyapunov exponent and the fast Fourier transform.

Over the last several decades, mass spectrometry has become one of the principle methods for compound identification and quantification. While for analytical purposes, fragments which are not fully characterized in terms of origin and intensity as a function of experimental conditions have been used, understanding the nature of those species is very important. Herein we discuss such issues relative to triacetone triperoxide (TATP) and its frequently observed fragment at m/z 89. This "fragment" has been identified as the gas-phase reaction product of TATP with one or two methanol molecules/ions. Additionally, the origin and conditions of other fragments at m/z 91, 75, and 74 associated with TATP will be addressed. Similar analytical issues associated with other multi-peroxide organic compounds [hexamethylene triperoxide diamine (HMTD), methyl ethyl ketone peroxides (MEKP)] will also be discussed. Solution storage conditions for TATP, HMTD, and tetramethylene diperoxide diamine dialdehyde have been determined. Graphical Abstract ᅟ.

The rheological dynamic characteristics of the functional polyurethane foam composite with solid additives (calcium iodate particles, aluminum flakes) were experimentally measured using an oscillatory rotational rheometer ARES-G2. Our previous studies demonstrated that the presence of the gas bubbles alters the rheology of the continuous liquid phase. The experimental tests results show that the apparent viscosity (the shear stress applied to a fluid divided by the shear rate) of the two-phase mixture increases with the concentration of the aluminum additive and decreases with the temperature rise. The rheological measurements showed that the functional foam exhibits a strong time-dependent and thixotropic (shear thinning) behavior. The rheological behavior of this composite can be described with the power law–generalized non-Newtonian fluid model. The apparent viscosity of the polyurethane increases with both the testing time (exponentially) and the solid content (polynomial) in the mixture. The measured rheological characteristics of the polyurethane-based functional foam will be helpful for material designers and developers.

With the recent availability of erythritol as an artificial sweetener, the synthesis of erythritol tetranitrate (ETN) has become economically feasible. This paper examines the eutectics of ETN, to see if it can be a useful component in melt-casted explosive formulations. To this end, we report several novel ETN–energetic eutectics, correct ratios, and melt-temperature for a previously reported eutectic, and we examine a new eutectic composed of insensitive explosives.

Pentaerythritol tetranitrate (PETN) finds many uses in the energetic materials community. Due to the recent availability of erythritol, erythritol tetranitrate (ETN) can now be readily synthesized. Accordingly, its complete characterization, especially its stability, is of great interest. This work examines the thermal decomposition of ETN, both through experimental and computational methods. In addition to kinetic parameters, decomposition products were examined to elucidate its decomposition pathway. It is found that ETN begins its decomposition sequence by a unimolecular homolytic cleavage of the internal and external O–NO2 bonds, while the competing HONO elimination reaction is largely suppressed. The global activation energy for decomposition is found to be 104.3 kJ/mol with a pre-exponential factor of 3.72 × 109 s–1. Despite the ability to exist in a molten state, ETN has a lower thermal stability than its counterpart PETN.

Currently there is a need for specialized pyrotechnic materials to combat the threat of biological weapons. Materials have been characterized based on their potential to produce heat and molecular iodine gas (I2) to kill spore-forming bacteria (e. g. anthrax). One formulation, already proven to kill anthrax simulants, is diiodine pentoxide with aluminum; however, it suffers from poor stability and storage problems. The heat and iodine gas output from this mixture and candidate replacement mixtures were measured with bomb calorimetry and extraction and analysis of I2 by UV-Vis. Of the mixtures analyzed, calcium iodate and aluminum was found to be the highest producer of I2. The heat output of this mixture and others can be tuned by adding more fuel, with the cost of some iodine. Products of combustion were analyzed by thermal analysis (SDT), XPS, XRD, and LC/MS. Evidence for various metal iodides and metal oxides was collected with these methods.

The rheological dynamic characteristics of the functional Polyurethane composite as well as its compounds ( triethanolamine (TEOA) and toluene-2,4-diisocyanate (TDI)) with and without solid additives (aluminum flakes) were experimentally measured using a computer-controlled mechanical spectrometer (rheometer) ARES-G2. Rheological studies showed that both components behave as viscous Newtonian fluids. TEOA exhibits a strong temperature-thickening behavior. TEOA with aluminum flake additives behaves as a viscous Newtonian fluid. The effective viscosity of the two-phase mixture increases with the concentration of the aluminum additive and decreases with the temperature rise. The rheometric tests showed that the effective viscosity of the TDI/Al mixture increases with the aluminum content. The mixture exhibits thermal-thickening and shear-thinning behaviors with the yield stress. The system can be described with the Bingham plastic model. It is determined that TEOA/TDI composite exhibits a strong time-thickening and shear-thinning behaviors. The rheological behavior of this composite can be described with the power-law generalized non-Newtonian fluid model. The effective viscosity of TEOA/TDI/Al composite increases with both the testing time (exponentially) and the aluminum content (polynomial) in the mixture. However, these shear-thinning composites obey the power-law generalized non-Newtonian fluid model, and their flow curves can be described by the logarithmic law.

Pipe bombs of steel or PVC fragment in reproducible patterns when similarly configured. The power of the explosion correlates with number, mass, and size of the fragments recovered, where a large number of small, low-mass fragments indicate a high-power event and vice versa. In discussing performance, describing pipe fragmentation pattern by fragment weight distribution mapping (FWDM) or fragment surface area distribution mapping (FSADM) was useful. When fillers detonated, detonation velocities of ~4.4 mm/μs were measured. In such cases, side walls of the pipe were thrown first; the average fragment velocity was ~1000 km/s. In deflagrations, the end cap was first thrown; fragment velocities were only ~240 km/s. Blast overpressures varied; at 10 feet, 2 × 12 inch steel pipes containing ~550 g of detonable mixture produced overpressures of 5-6 psi; similar nondetonating pipes produced less than 2 psi. Maximum fragment throw distances were 250-300 m, with an average of ~100 m.

Copper acetylide is used to describe copper and acetylene containing compounds. Depending on the valence of copper involved in reaction with acetylene, cuprous acetylide is formed from cuprous ion (Cu+) while cupric acetylide is formed from cupric ion (Cu2+). This study addresses the use of copper materials for removal of mercury and the potential for accidental accumulation of copper acetylides in the process. Alumina supports with copper oxide, copper carbonate or copper sulfide were exposed to acetylene and a variety of analytical techniques used to evaluate their potential for accumulation of copper acetylides. Copper oxide and copper carbonate exposed to acetylene did not demonstrate accumulation of either cuprous or cupric acetylides. However, resulting accumulated materials were energetic as they decomposed with release of heat during Differential Scanning Calorimeter analysis. The exothermic event was not excessive and it was speculated that the reaction involved copper oxide and carbon at elevated temperature. There was no apparent reaction between copper sulfide and acetylene. The condition for exposure of acetylene to the copper materials in this study was extreme. It concludes that when the copper materials are used for mercury recovery there is no apparent accumulation of copper acetylides.

Erythritol tetranitrate (ETN) was prepared independently by two research groups from the USA and the Netherlands. The partially nitrated impurities present in ETN were studied using liquid chromatography-mass spectrometry to address the ultimate challenge in forensic explosives investigations, i.e., providing chemical and tactical information on the production and origin of the explosive material found at a crime scene. Accurate quantification of the tri-nitrated byproduct erythritol trinitrate (ETriN) was achieved by in-lab production of an ETriN standard and using custom-made standards of the two isomers of ETriN (1,2,3-ETriN and 1,2,4-ETriN). Large differences in levels of ETriN were observed between the two sample sets showing that, even when similar synthesis routes are employed, batches from different production locations can contain different impurity profiles. In one of the sample sets the ratios of the lesser partially nitrated impurities, EDiN and EMN, in the ETN samples could be determined. The impurity profiles enable prediction of post-synthesis work-up steps by reduction of the level of partially nitrated products upon recrystallization. However, impurity analysis does not enable predictions with respect to raw material or synthesis route used. Nonetheless, characteristic impurity profiles obtained can be used in forensic casework to differentiate or link ETN samples. However, forensic interpretation can be complicated by acid catalyzed degradation which can cause changes in impurity levels over time. The high food-grade quality of the erythritol precursor materials did not provide other impurity markers using the LC-MS methods in this study. To expand our framework of chemical attribution a follow-up study will be reported that focuses on stable isotope analysis of ETN and its precursor materials that potentially allow predictions for forensic explosives intelligence. © 2019 Elsevier B.V. Chemicals / CAS erythritol, 149-32-6, 7541-59-5; erythrityl tetranitrate, 7297-25-8

Photon Doppler velocimetry (PDV) has become an important technique for explosives diagnostics over the last two decades. However, the inherent necessity for a very high-speed digitizer has rendered this technology expensive and inaccessible to the general research community. This letter reports a microwave-modulated PDV method, based on the conventional PDV testing, in which an RF modulator was used to directly modulate the current of a laser transmitter. Carrying the modulated frequency, the received PDV beat frequency was then engaged with a second beat frequency at the photo receiver, resulting in a low detection frequency. This resulting frequency can be detected using a digitizer with a lower sampling rate while retaining the information necessary for high-speed velocimetry measurement.

The interactions of energetic materials and polymers have important implications in safety, long-term storage, and performance of explosives and explosive mixtures. Atomic force microscopy was used to investigate adhesion forces at the molecular scale of nine energetic materials, organic explosives and energetic salts, on eleven common polymers (polyethylene, polyvinylalcohol, poly(vinyl chloride), polycarbonate, polystyrene, poly(methyl methacrylate), styrene-butadiene rubber, poly(4-vinyl phenol), poly(2,6-dimethylphenylene oxide), poly(2,6-diphenyl-p-phenylene oxide) (Tenax®), and polytetrafluoroethylene (Teflon®)). Teflon was the least adhesive polymer to all energetic materials, while no distinct trend could be elucidated among the other polymers or energetic materials.

Kinetic behavior of ammonia decomposition at titanium dioxide nanotube photosensitive anode was studied. Ammonia was dissolved into water to form solutions with difference concentrations. The ammonia concentration ranges from 0.025 wt% to 10 wt%. Time-dependent open-circuit potential was measured to examine the photochemical response of the cell. The ammonia decomposition behavior was confirmed by measuring the decrease in pH values of the solutions. In addition, the kinetic behavior of ammonia decomposition was characterized under the actions of both ultra violet light irradiation and polarization. The current density values at the titanium dioxide nanotube anode during anodic polarization and UV light irradiation tests were used to compare the ammonia decomposition rates associated with photon excitation and polarization. The double–layer capacitance was estimated as high as 35 F/m indicating the excellent charge storing capability of Original Research Article Gan et al.; ACRI, 3(4): 1-12, 2016; Article no. ACRI.25848 2 the nanotube photosensitive anode. The effect of ammonia concentration on the open-circuit potential was also observed. In the lower ammonia concentration range, the change in the open circuit potential increase with the increasing in the ammonia concentration. Interestingly, in the higher concentration range from 2.5 wt% to 10 wt%, the change in the open circuit potential reveals a reversed trend.

The synthesis and decomposition of hexamethylene triperoxide diamine (HMTD) were studied. Mechanisms were proposed based on isotopic labeling and mass spectral interpretation of both condensed phase products and head-space products. Formation of HMTD from hexamine appeared to proceed from dissociated hexamine as evident from scrambling of the 15N label when synthesis was carried out with equal molar labeled/unlabeled hexamine. Decomposition of HMTD was considered with additives and in the presence and absence of moisture. In addition to mass spectral interpretation, density functional theory (DFT) was used to calculate energy differences of transition states and the entropies of intermediates along different possible decomposition pathways. HMTD is destabilized by water and citric acid making purification following initial synthesis essential in order to avoid unanticipated violent reaction.

There is a need in the explosives detection community for an insensitive, storage-stable source of triacetone triperoxide (TATP). To achieve this, the solvent evaporation microencapsulation technique was used to disperse TATP in a plastic matrix. This lowered the shock sensitivity greatly and prevented loss of TATP at room temperature, allowing for easy long-term storage. It was then demonstrated that pure TATP vapor was released on demand from the matrix by heating.

Ballistic projectiles (fragments, missiles) thrown due to the explosions can be a greater hazard than the blast wave. Safe distances from the blast can be readily calculated since it falls off as the cube root of distance. Far more complex is predicting how far fragments may be thrown. This work develops an engineering method to predict aerodynamics of explosive ballistic projectiles (EBPs) of arbitrary shapes. Incorporating the numerical solution of the equations of the dynamic motion of projectile with a complex variable method (“linearization of single-bonded area”), the velocities and the trajectories of arbitrary shape EBPs have been determined. The results are compared to previously developed model predictions and the fragment recovery tests results.

A rheometric characterization of the functional Polyurethane (PU) foam composite with and without solid additives (aluminum flakes) were experimentally measured using a computer controlled mechanical spectrometer (rheometer) ARES-G2. It is determined that PU composite exhibits a strong time thickening and shear thinning behavior. The rheological behavior of this composite can be described with the power-law generalized non-Newtonian fluid model. The rheometric tests showed that the PU/Al mixture exhibits thermal thickening and shear thinning behavior with the yield stress. The system can be described with the power-law generalized non-Newtonian fluid (Ostwald-de-Waele) model. The effective viscosity of PU composite increases with both the testing time (exponentially) and the solid content (polynomial) in the mixture.

RATIONALE Hexamethylene triperoxide diamine (HMTD) is a sensitive peroxide explosive first synthesized in 1885. HMTD exhibits an unusual gas-phase phenomenon in the presence of alcohols that has been previously observed, but incorrectly resolved. We are attempting to determine this specific mechanism. METHODS We used positive ion mode atmospheric pressure chemical ionization (APCI) as the interface to the mass spectrometer. HMTD was infused with various solvents including 18O- and 2H-labeled methanol in order to determine gas-phase reaction mechanisms. RESULTS Based on these labeled experiments, it was determined that, under APCI conditions, the alcohol oxygen attacks a methylene carbon of HMTD and releases H2O2. This was attempted with nine different alcohols and, in each case, the alcohol is fully incorporated into the molecule with the peroxide release. A mechanism for this reaction has been proposed. CONCLUSIONS This work appears to have confirmed the gas-phase reaction mechanism of HMTD with alcohols. As we continue efforts to characterize this unusual molecule, the information may prove useful in determining formation and degradation mechanism(s). In addition, this property of HMTD may find use in other fields of science. Copyright © 2014 John Wiley & Sons, Ltd.

This work deals with synthesis and characterization of polyaniline and titanium dioxide nanocomposites for explosive detection and mitigation. The titanium dioxide nanotube array was prepared through electrochemical oxidation of pure titanium in a fluorine ion-containing ethylene glycol water solution followed by annealing at 450 °C in air. Polyaniline was obtained by electrochemical polymerization from an aniline and sulfuric acid solution. Both polyaniline and the nanotube show sorption of 2,4,6-trinitrotoluene (TNT) vapor at 60 °C. Polyaniline modified by alginic acid sodium salt caused color change of TNT solutions. Polyaniline-based sensor showed decrease of electrical resistance in TNT acetonitrile solutions. Ultraviolet light response tests revealed that TNT caused significant drop in open circuit voltage of the titanium dioxide nanotube. In addition, the polyaniline/titanium oxide nanocomposites show colorimetric responses in the explosive solution, which makes them have multiple response mechanisms for nitro-aromatic explosive detection and mitigation.

A survey of the stability and performance of eleven solid oxidizers and thirteen fuels was performed by differential scanning calorimetry, simultaneous differential thermolysis, and hot-wire ignition. Sugars, alcohols, hydrocarbons, benzoic acid, sulfur, charcoal, and aluminum were used as fuels; all fuels except charcoal and aluminum melted at or below 200 °C. It was found that the reaction between the oxidizer and the fuel was usually triggered by a thermal event, i.e., melt, phase change, or decomposition. Although the fuel usually underwent such a transition at a lower temperature than the oxidizer, the phase change of the fuel was not always the triggering event. When sugars or sulfur were the fuels, their phase change usually triggered their oxidation. However, three oxidizers, KNO3, KClO4, and NH4ClO4, tended to react only after they underwent a phase change or began to decompose, which meant that their oxidization reaction, regardless of the fuel, was usually above 400 °C. KClO4–fuel mixtures decomposed at the highest temperatures, often over 500 °C, with the ammonium salt decomposing almost 100 °C lower. Mixtures with ammonium nitrate (AN) also decomposed at much lower temperatures than those with the corresponding potassium salt. With the exception of the oxidizers triggered to react by the phase changes of the polyols and sulfur, the oxidizer–fuel mixtures generally decomposed between 230 and 300 °C, with AN formulations generally decomposing at the lowest temperature. In terms of heat release, potassium dichromate–fuel mixtures were the least energetic, generally releasing less than 200 J g−1. Most of the mixtures released 1000–1500 J g−1, with potassium chlorate, ammonium perchlorate, and AN releasing significantly more heat, around 2000 J g−1. When the fuel was aluminum, most of the oxidizers decomposed below 500 °C leaving the aluminum to oxidize at over 800 °C. Only two oxidizers reduced the temperature of the aluminum exotherm—chlorate and potassium nitrite. To go to temperatures above 500 °C, unsealed crucibles were necessary, and with these containers, the endothermic volatilization of reactants and products effectively competed against the exothermic decomposition so that heat release values were artificially low.

Urea nitrate (UN) has not found use as a legitimate explosive but is commonly used as an improvised explosive. The dehydration product of UN is nitrourea (NU). Visually both UN and NU are white solids that both melt around 160 °C. Other properties differ markedly as might be expected from an inorganic salt (UN) and an organic molecular compound (NU). An extensive physical characterization of NU and UN is reported. Two reported routes to the NU product are compared and a decomposition mechanism of UN proposed.

Conditions, which result in the formation of tria- cetone triperoxide (TATP) or diacetone diperoxide (DADP) from acetone and hydrogen peroxide (HP) were studied for the purposes of inhibiting the reaction. Reaction of HP with acetone precipitates either DADP or TATP, but the overall yield and amount of each was found to depend on (1) reac- tion temperature, (2) the molar ratio of acid to HP/acetone, (3) initial concentrations of reactants, and (4) length of reac- tion. Controlling molar ratios and concentrations of starting materials was complicated because both sulfuric acid and hydrogen peroxide were aqueous solutions. Temperature exercised great control over the reaction outcome. Holding all molar concentrations constant and raising the tempera- ture from 5 to 258C showed an increase of DADP over TATP formation and a decrease in overall yield. At 258C a good yield of TATP was obtained if the HP to acetone ratio was kept between 0.5-to-1 and 2-to-1. At constant temperature and HP-to-acetone held at one-to-one ratio, acid-to-HP molar ratios between 0.10 : 1 and 1.2 : 1 pro- duced good yield of TATP. Plotting the molality of HP vs. that of sulfuric acid revealed regions, in which relatively pure DADP or pure TATP could be obtained. In addition to varying reaction conditions, adulterants placed into ace- tone were tested to inhibit the formation of TATP. Because there is much speculation of the relative stability, sensitivity, including solvent wetting of crystals, and performance of DADP and TATP, standard tests (i.e. DSC, drop weight impact, and SSED) were performed.

Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression. Graphical Abstract ᅟ.

Vapor pressure is a fundamental physical characteristic of chemicals. Some solids have very low vapor pressures. Nevertheless numerous chemical detection instruments aim to detect vapors. Herein we address issues with explosive detection and use thermogravimetric analysis (TGA) to estimate vapor pressures. Benzoic acid, whose vapor pressure is well characterized, was used to calculate instrumental parameters related to sublimation rate. Once calibrated, the rate of mass loss from TGA measurements was used to obtain vapor pressures of the 12 explosives at elevated temperature: explosive salts – guanidine nitrate (GN); urea nitrate (UN); ammonium nitrate (AN); as well as mono-molecular explosives – hexanitrostilbene (HNS); cyclotetramethylene-tetranitramine (HMX), 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diaza-tetracyclododecane (TEX), cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate (PETN), 3-nitro-1,2,4-triazol-5-one (NTO), 1,3,3-trinitroazeditine (TNAZ), triacetone triperoxide (TATP), and diacetone diperoxide (DADP). Ambient temperature vapor pressures were estimated by extrapolation of Clausius-Clapeyron plots (i.e. ln p vs. 1/T). With this information potential detection limits can be assessed.

The present study documents the results of a literature search and experimental work to assess the risks of mixing dilute H 2 O 2 and acetone solutions. The use of dilute H 2 O 2 to clean chemical vessels is common, but it has been shown to be potentially hazardous due to the reaction of H 2 O 2 with organic solvents to form explosive peroxides. Mixing concentrated H 2 O 2 and acetone with an acid catalyst is known to form the shock and friction sensitive explosives triacetone triperoxide (TATP) and diacetone diperoxide (DADP). A search of the chemical literature was unable to identify any directly applicable research or technical information that addressed the potential formation of explosive peroxides when mixing dilute H 2 O 2 and acetone solutions. The conclusion of these experiments is that when mixing dilute solutions, such as less than 3% H 2 O 2 and 7% acetone, the solutions are unlikely to form significant amounts of TATP or DADP. In the presence of an acid catalyst, hundreds of parts per million of organic peroxides can be formed. Although TATP is relatively insoluble in water, it is soluble at roughly the 15 ppm level and higher for acetone and H 2 O 2 solutions, thus any acetone peroxides that are formed without acid catalyst should remain soluble in the aqueous cleaning solution.

Thermal behaviors, vapor pressures, densities, and drop weight impact results, as well as analytical protocols, are reported for three tetranitrate esters: erythritol tetranitrate (ETN), 1,4-dinitrato-2,3-dinitro-2,3bis(nitratomethylene) butane (DNTN), and pentaerythritol tetranitrate (PETN). ETN and DNTN both melt below 100 °C and have ambient vapor pressures comparable to TNT. While LC/MS was shown to be a viable technique for analysis of all three tetranitrate esters, only ETN was successfully analyzed by GC/MS. Performance of these nitrate esters as evaluated in lab using the small-scale explosivity device (SSED) suggested RDX≫DNTN>PETN>ETN. Detonation velocities were calculated using Cheetah 6.0. Since the starting material is now widely available, it is likely that law enforcement will find ETN in future improvised explosive devices. This paper with its analytical schemes should prove useful in identification of this homemade explosive.

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.

The safe decomposition of solid TATP (triacetone triperoxide) explosive is examined theoretically. The route to destruction starts with formation of metal complexes between a metal ion and the TATP molecule. The second step is decomposition of the molecules into stable final products. We examined the structure and stability of both metal ion (including Na(+), Cu(+), Cu(2+), Co(2+), and Zn(2+)) and proton complexes with TATP using quantum chemical calculations at the DFT-PBE0 level of theory. In addition, for each ion complex, we determined the initial steps in the pathway to decomposition together with the associated transition states. We find that the products of decomposition, in particular, acetone, are also stabilized by ion metal complexes. In agreement with experiment, we find the best candidates for metal ion induced decomposition are Cu(2+) and Zn(2+).