Hexamethylene Triperoxide Diamine Research Articles

Sensor-monitored impact sensitivity investigations on HMTD of different aging stages with accompanying PTR-TOF measurements of the substances

ABSTRACT Hexamethylene triperoxide diamine (HMTD) is a commonly used homemade explosive due to its simple synthesis and availability of reactants. However, its impact sensitivity may vary significantly depending on synthesis methods and possibly substance aging, presenting safety concerns during handling. In this study, two batches of HMTD, one stored for 3 months and one freshly synthesized, were investigated. Analytical techniques including Raman spectroscopy and PTR-ToF were utilized for the HMTD specimen. A custom-designed drop hammer based on OZM’s Ball Impact Tester, equipped with optical and acoustic sensors, was employed to evaluate impact sensitivity and chemical reaction process. The setup was tested and validated with HMTD, TATP and lead azide and silver azide. Extracted features of sensor data were subjected to multivariate statistical analysis (LDA, PCA) to assess the impact of aging to impact sensitivity and reaction characteristics. The study aimed to determine the correlation between substance composition and reaction behavior. The results contribute to the understanding of the influence of aging on the response and mechanical sensitivity of HMTD as well as the batch-to-batch variation.

Rapid and selective screening of organic peroxide explosives using acid-hydrolysis induced chemiluminescence

Organic peroxide explosives (OPEs) are unstable, non-military, contemporary security threats often found in improvised explosive devices. Chemiluminescence (CL) can be used to detect OPEs, via radical formation consisting of peroxide moieties (-O-O-) under acidic conditions. However, selectivity for specific OPEs is hampered by the ubiquitous background of H2O2. Herein, we report the differentiation of hexamethylene triperoxide diamine (HMTD), triacetone triperoxide (TATP), and methyl ethyl ketone peroxide (MEKP) by specific flow injection analysis–CL (FIA-CL) signal profiles, after H2SO4 treatment. The radical degradation pathway of each structure, and its corresponding FIA-CL profile, was explored using mass spectrometry to reveal the rapid loss of -O-O- from TATP and HMTD structures, while MEKP formed CL signal-sustaining oligomers, as opposed to the immediate attenuation of H2O2. The CL response for OPEs in an aqueous media, measured via the described FIA-CL method, enabled ultra-trace limits of detection down to 0.40 μM for MEKP, 0.43 μM for HMTD, and 0.40 μM for TATP (combined linear range 1–83 μM with 95% confidence limit, n = 12). Expanded uncertainties of measurement (UM) of MEKP = ±0.98, HMTD = ±1.03, and TATP = ±1.1 (UM included probabilities of false positive and false negative as well as standard deviations of % recoveries and limit of detections of OPEs). Direct aqueous sample introduction via FIA-CL thus offers the prospect of rapid and selective screening of OPEs in security-heightened settings (e.g., airports), averting false positives from more ubiquitous H2O2.

Chiral explosives: A theoretical investigation of structure and chiroptical properties of triacetone triperoxide and hexamethylene triperoxide diamine.

Triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are cyclic peroxides that exhibit atropisomerism resulting from restricted rotation around three peroxide bonds. As a result, one pair of enantiomers with D3 symmetry and another pair of enantiomers with C2 symmetry can be identified. Previous studies, based on mass spectrometry data and computational results, have shown that conformations of TATP with D3 and C2 symmetry can be isolated. Assuming that enantiomer samples of TATP and HMTD can be obtained with sufficient enantiopurity, we investigated their chiroptical properties, namely, optical rotatory dispersion (ORD), vibrational circular dichroism (VCD), and Raman optical activity (VROA). ORD curves and VCD spectra are seen to be very similar for D3 - and C2 -symmetric atropisomers with the same overall helicity. Predicted VROA results, however, show significant differences between D3 - and C2 -symmetric atropisomers with the same overall helicity. The D3 -symmetric atropisomer is predicted to exhibit considerably larger magnitude vibrational optical activity signals than the C2 -symmetric atropisomer.

Direct Determination of Peroxide Explosives on Polycarbazole/Gold Nanoparticle-Modified Glassy Carbon Sensor Electrodes Imprinted for Molecular Recognition of TATP and HMTD.

Since peroxide-based explosives (PBEs) lack reactive functional groups, they cannot be determined directly by most detection methods and are often detected indirectly by converting them to H2O2. However, H2O2 may originate from many sources, causing false positives in PBE detection. Here, we developed a novel electrochemical sensor for the direct sensitive and selective determination of PBEs such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) using electrochemical modification of the glassy carbon (GC) electrode with PBE-memory polycarbazole (PCz) films decorated with gold nanoparticles (AuNPs) by cyclic voltammetry (CV). The prepared electrodes were named TATP-memory-GC/PCz/AuNPs (used for TATP determination) and HMTD-memory-GC/PCz/AuNPs (used for HMTD detection). The calibration lines of TATP and HMTD were found in the concentration range of 0.1-1.0 mg L-1 using the net current intensities of differential pulse voltammetry (DPV) versus analyte concentrations. The limit of detection (LOD) commonly found was 15 μg L-1 for TATP and HMTD. The sensor electrodes could separately determine intact TATP and HMTD in the presence of nitro-aromatic, nitramine, and nitrate ester energetic materials. The proposed electrochemical sensing method was not interfered by electroactive substances such as paracetamol, caffeine, acetylsalicylic acid, aspartame, d-glucose, and detergent (containing perborate and percarbonate) used as camouflage materials for PBEs. This is the first molecularly imprinted polymeric electrode for PBEs accomplishing such low LODs, and the DPV method was statistically validated in contaminated clay soil samples against the GC-MS method for TATP and a spectrophotometric method for HMTD using t- and F-tests.

Electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS) applied to the analysis of explosives

Electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS) was applied to the analyses of explosives including HMTD (hexamethylenetriperoxidediamine), RDX (cyclotrimethylene trinitroamine), HMX (cyclotetramethylenetetranitroamine), PETN (pentaerythritol tetranitrate), and TNT (2,4,6-trinitrotoluene) in positive- and negative-mode of operation. A mixture of H2O/CH3OH (9/1) containing 0.01 M trifluoroacetic acid (TFA) was used as a solvent for vacuum electrospray. For all explosives described above, intact molecules were detected by EDI/SIMS. HMX which is the least volatile compound tested could be readily detected in both positive- and negative-mode of operations. Nitramines of RDX and HMX were detected as proton- and Na+-bound cluster ions with H2O and CH3OH ligands. TNT and the nitrate ester PETN were not detected in positive mode. In negative mode, RDX, HMX and PETN were detected as adduct ions with NO2−, NO3−, and CF3COO−. TNT gave TNT−• and fragment ions similar to those detected in atmospheric-pressure chemical ionization. The characteristic difference in reactivity between the nitramine compounds (RDX and HMX) and the nitrate ester compound (PETN) is likely to be due to the more diffused negative charge in nitrate ester groups than in nitro groups.

Thermochemical analysis of improvised energetic materials by laser-heating calorimetry

Thermochemical analysis of six improvised energetic materials was carried out using laser-heating calorimetry to demonstrate the feasibility of this methodology to provide distinctive thermal signatures and information on the material shelf life. The chemicals evaluated were erythritol tetranitrate, hexamethylene triperoxide diamine (HMTD), poor-man's C-4 (blend of potassium chlorate and petroleum jelly), R-salt (represented by 1,3,5-trinitroso-1,3,5-triazinane), triacetone triperoxide (TATP), and urea nitrate. The measurement technique records the temperature rise with time, from which one can estimate the material endothermic/exothermic behavior, energy release rate, and total specific energy release (heating value, enthalpy of explosion), as well as the sample mass rate of change. Measurements were carried out in an inert nitrogen environment at laser heating rates up to 60 K/s with steady-state temperatures reaching about 933 K. Sample initial mass was between 1.0 mg and 4.0 mg. Experiments were carried out with freshly prepared samples, as well as refrigerated samples and those stored at room (laboratory) temperature for three years. Results indicated that the samples reacted rapidly between 0.50 s and 0.75 s, being initiated near the material decomposition temperature. The total specific energy release, using two different thermal-analysis models, was calculated and compared to values available in the literature. One model represents sample reaction and decomposition within the spherical reactor volume, while the second represents reactions emanating from sample in a pan centrally positioned within the sphere; the former model was found to be the more appropriate approach for these faster-reacting energetic materials. The thermal signatures (temperature-time derivatives with temperature) were different for each chemical, a feature that may be important for energetic material identification. The initiation and peak reaction temperatures were found to decrease with increasing initial sample mass. Also, the shelf life for TATP and HMTD was found not to degrade under nonideal conditions after three years.

The isotopic compositions of hexamine solid fuel tablets used to manufacture hexamethylene triperoxide diamine (HMTD) explosive

Hexamine, derived from solid fuel tablets, is a potential source for a number of home-made explosives including the primary high explosive hexamethylene triperoxide diamine (HMTD). Therefore, a means to characterise hexamine samples and to link HMTD with precursor hexamine may provide investigative intelligence to counter-terrorism agencies.We report the hydrogen, carbon and nitrogen isotopic compositions of hexamine isolated from retail samples of solid fuel tablets. Hydrogen isotopic compositions ranged from –123.0 to +172.6‰, carbon isotopic compositions from –47.1 to –27.6‰ and nitrogen isotopic compositions from –3.1 to +0.3‰. Despite within- and between-tablet inhomogeneity, a combination of these data could be considered characteristic of specific brands or manufacturers.Ten samples of hexamine were each used to synthesize four batches of HMTD using two isotopically distinct sources of hydrogen peroxide. The δ13C and δ15N compositions of the HMTD ranged from –48.8 to –31.5‰ for carbon and from +13.7 to +17.8‰ for nitrogen. δ2H compositions across all batches of HMTD was much wider than previously reported; –109.3 to +196.6‰.The changes in carbon and nitrogen isotopic compositions, progressing from hexamine to HMTD, could be explained by a reaction mechanism involving the decomposition of hexamine to methylimine and formaldehyde. Data also supported a mechanism whereby the hydrogen atoms of HMTD were derived from hexamine and not from other reagents.Based on the relationships Δ2HHEXAMINE-HMTD and Δ13CHEXAMINE-HMTD, a rule-of-thumb was proposed to identify possible hexamine precursors of HMTD.

Rapid and selective on-site detection of triacetone triperoxide based on visual colorimetric method

In this work, a visual colorimetric method for the rapid and selective detection of triacetone triperoxide is reported. This visual colorimetric method is based on the reaction between potassium titanyl oxalate and hydrogen peroxide (H2O2) released from triacetone triperoxide degradation. Potassium titanyl oxalate can selectively react with H2O2 to form peroxo-titanic acid (an orange complex), enabling the colorimetric detection of triacetone triperoxide. Based on the theory that triacetone triperoxide produces hydrogen peroxide under acidic conditions, acid types, acid concentration, response time, visual limit of detection, and reactants ratio are systematically studied simultaneously for this colorimetric method. Under sulfuric acid concentration is 60%, the proposed method can almost detect triacetone triperoxide instantly, and the color of the solution reaches the maximum within 1 min and remains stable with a visual limit of detection as low as 3.0 × 10−5 mol/L. Interference experiments were carried out on other kinds of explosives (hexamethylene triperoxide diamine, trinitrotoluene, etc.). The use of colorimetric card brings great convenience to the rapid, qualitative, and semi-quantitative on-site detection of triacetone triperoxide. Because of its rapidity, high sensitivity, simplicity, and selectivity, the proposed visual colorimetric method can serve as a valuable and promising reference for triacetone triperoxide’s rapid, qualitative on-site detection.

Some Ions of Hexamethylene Triperoxide Diamine - A DFT Treatment

Hexamethylene triperoxide diamine (HMTD) is one of the peroxide type organic explosive which is sensitive to various stimuli including electrical charging. In the present study, within the restrictions of density functional theory at the level of B3LYP/6-311++G(d,p) some ionic forms of HMTD have been investigated. Its anionic and cationic forms considered all undergo decomposition. The monoanion form exhibited cleavage of two peroxide bonds and two C-H bonds whereas the monocation and dication forms show the rupture of O-CH2 bonds. Some quantum chemical properties and UV-VIS spectra of HMTD and the decomposed products were obtained and discussed.

Study into parameters of the dust explosion ignited by an improvised explosion device filled with organic peroxide

Dust explosion poses a significant hazard in industry. An explosion of dispersed dust can be ignited by an improvised explosive device. The article deals with the study of explosion parameters of representative samples of dispersed dust ignited by an improvised explosive device. Hexamethylene triperoxide diamine was used as an igniter. Lycopodium clavatum spores were used as a standard sample. Furthermore, dust samples were selected from those types of operations that may be endangered if an improvised explosive device is used as an igniter. Wheat flour and beech wood dust were selected as representative samples. The achieved parameters of explosion pressure and explosion constant Kst were on average by 5–15% lower than the parameters achieved when using a commercial igniter. The Pmax value and the inflection point of the explosion record were reached 7–12 ms earlier than those achieved with a commercially available igniter. The findings may be relevant in the design of explosion prevention devices. New types of explosion prevention devices can be designed to reduce the risk of explosion of dispersed combustible dust caused by improvised explosive devices, e.g. in a case of terrorist attack on the objects with the occurrence of dust clouds.

Direct Electrochemical Determination of Peroxide-Type Explosives Using Well-Dispersed Multi-Walled Carbon Nanotubes/Polyethyleneimine-Modified Glassy Carbon Electrodes.

The sensitive and selective determination of peroxide-based explosives (PBEs) in the field/on site is an important analytical challenge. Most methods claiming to detect PBEs are indirect, actually detecting their decomposition product, H2O2. Here, we present an electrochemical sensor for direct detection of organic peroxide explosives, that is, triacetone triperoxide (TATP) and hexamethylenetriperoxide diamine (HMTD), using well-dispersed multiwalled carbon nanotubes/polyethyleneimine (MWCNTs/PEI)-modified glassy carbon (GC) electrode, namely, GC/MWCNTs/PEI electrode. This is the first use of the conductive polyelectrolyte PEI as an electrode modifier for pristine PBE sensing. The potential range, scan rate, solvent selection, and supporting electrolyte concentration were optimized for PBEs. As a distinct advantage over other similar methods, our sensor electrode responded to intact TATP solutions in neutral medium, meaning that TATP did not interact with acids/bases that would transform it into H2O2. Calibration curves were linear in the range of 10-200 mg L-1 for TATP and 25-200 mg L-1 for HMTD. Using differential pulse voltammetry, detection limits of 1.5 mg L-1 TATP and 3.0 mg L-1 HMTD were obtained from direct electrochemical reduction in 80/20% (v/v) H2O-acetone solvent medium. Electroactive camouflage materials such as passenger belongings (e.g., sweetener, detergent, sugar, and paracetamol-caffeine-based analgesic drugs), common ions, and other explosives were shown not to interfere with the proposed method. The nonresponsive behavior of our electrode to H2O2 prevents "false positives" from other peroxide materials of everyday use. This electrochemical sensor could also detect other nitro-explosives at different potentials and was statistically validated against standard GC-MS and spectrophotometric methods.

Detection of Triacetone Triperoxide (TATP) and Hexamethylene Triperoxide Diamine (HMTD) from the Gas Phase with Differential Ion Mobility Spectrometry (DMS)

One of the significant problems in the modern world is the detection of improvised explosives made of materials synthesized at home. Such compounds include triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD). An attempt was made to construct an instrument allowing for the simultaneous detection of both compounds despite the large difference of vapor pressure: very high for TATP and very low for HMTD. The developed system uses differential ion mobility spectrometry (DMS) in combination with a specially designed gas sample injection system. The created system of detectors allowed for the detection of a high concentration of TATP and a very low concentration of HMTD. TATP detection was possible despite the presence of impurities—acetone remaining from the technological process and formed as a coproduct of diacetone diperoxide (DADP) synthesis. Ammonia added to the carrier gas improved the possibility of detecting the abovementioned explosives, reducing the intensity of the acetone signal. The obtained results were then compared with the detection capabilities of drift tube ion mobility spectrometer (DT-IMS), which has not made possible such detection as DMS.

Paper spray ionization-high-resolution mass spectrometry (PSI-HRMS) of peroxide explosives in biological matrices.

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 vitro metabolism of HMTD and blood stability and toxicity of peroxide explosives (TATP and HMTD) in canines and humans

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.

Feasibility of use of medical dual energy scanner for forensic detection and characterization of explosives, a phantom study.

Detection of explosives is a challenge due to the use of improvised and concealed bombs. Post-bomb strike bodies are handled by emergency and forensic teams. We aimed to determine whether medical dual-energy computed tomography (DECT) algorithm and prediction model can readily detect and distinguish a range of explosives on the human body during disaster victim identification (DVI) processes of bombings. A medical DECT of 8 explosives (Semtex, Pastex, Hexamethylene triperoxide diamine, Acetone peroxide, Nitrocellulose, Pentrite, Ammonium Nitrate, and classified explosive) was conducted ex-vivo and on an anthropomorphic phantom. Hounsfield unit (HU), electron density (ED), effective atomic number (Zeff), and dual energy index (DEI),were compared by Wilcoxon signed rank test. Intra-class (ICC) and Pearson correlation coefficients (r) were computed. Explosives classification was performed through a prediction model with test-retest samples. Except for DEI (p = 0.036), means of HU, ED, and Zeff were not statistically different (p > 0.05) between explosives ex-vivo and on the phantom (r > 0.80). Intra- and inter-reader ICC were good to excellent: 0.806 to 0.997 and 0.890, respectively. Except for the phantom DEI, all measurements from each individual explosive differed significantly. HU, ED, Zeff, and DEI differed depending on the type of explosive. Our decision tree provided Zeff and ED for explosives classification with high accuracy (83.7%) and excellent reliability (100%). Our medical DECT algorithm and prediction model can readily detect and distinguish our range of explosives on the human body. This would avoid possible endangering of DVI staff.

Tfbar Sensors for Detection of Explosives Substances

Tfbar Sensors for Detection of Explosives Substances

Explosive vapor detection using novel graphdiyne nanoribbons—a first-principles investigation

We investigated the capability of graphdiyne nanoribbon (GdNR) to detect the existence of explosive vapors like hexogen or cyclonite, hexamethylene triperoxide diamine (HMTD), and 2,4,6-trinitrotoluene (TNT) using ATK-VNL package. In order to determine the sensing response of GdNR towards these explosive vapors, the geometric firmness of the material is first verified with the assistance of cohesive energy. Then, electronic characteristics like the projected density of states (PDOS) spectrum, band structure, and electron density are examined for both isolated and explosive vapor adsorbed GdNR. Further, adsorption attributes like average energy gap variation, enthalpy adsorption, adsorption energy, and Bader charge transfer are explored for explosive vapor adsorbed GdNR. Moreover, there is a need for rapid detection of explosive vapors using solid-state chemical sensors. The scrutinization of these attributes affirms the employment of GdNR as a chief material in a chemical nanosensor to perceive the availability of the mentioned explosive vapors.

Identification of post-blast explosive residues using direct-analysis-in-real-time and mass spectrometry (DART-MS)

Application of Direct-Analysis-in-Real-Time (DART) ionization with mass spectrometry (DART-MS) to identify homemade explosive (HME) residue recovered from genuine post-blast bomb fragments is presented. A variety of simulated improvised explosive devices (IEDs) were configured to replicate post-blast debris representative of materials encountered in real forensic casework scenarios. Peroxide-based HME was used as explosive filler: triacetone triperoxide (TATP), hexamethylene triperoxide diamine (HMTD) and methyl ethyl ketone peroxide (MEKP). Each IED was fired separately and the recovered fragments analyzed using full scan with high-resolution mass spectrometry. Fragments were analyzed directly and indirectly using cotton swabs and the target explosive was detected using either sampling technique. This work demonstrates the forensic validity of DART-MS to provide rapid and quality-assured identification of explosive residues from real post-blast IED fragments.

Sensors Using the Molecular Dynamics of Explosives in Carbon Nanotubes Under External Uniform Electric Fields.

Possessing a simulated sensor device to identify explosives is of extreme interest to the area of public security to fight against terrorism. In light of this, a carbon armchair nanotube was modeled under the action of an external, longitudinal and uniform electric field at an initial temperature of 1 mK simulation, causing the explosive molecules under analysis to rotate through the carbon nanotube, due to an evanescent effect generated from the action of an electric current and magnetic field induced in this system, and thus behaving as a selective temperature sensor and spinning radius for the molecules. For this, molecular dynamics was used to study the physicochemical properties of the molecules' interactions with a carbon nanotube. The following physical properties, as well as the kinetic, potential, and total energy were calculated for the 2,4,6-trinitrotoluene (TNT), triacetone triperoxide (TATP), hexogen (RDX), hexamethylene triperoxide diamine (HMTD), octogen (HMX) and pentaerythritol tetranitrate (PETN) explosives: thermodynamic conditions such as temperature; entropy variation; and distance between the molecules' center of mass from an armchair type carbon nanotube.

Variation in the headspace of bulk hexamethylene triperoxide diamine (HMTD): Part II. Analysis of non-detonable canine training aids

Detection canines are a major source of protection against the powerful peroxide explosive hexamethylene triperoxide diamine (HMTD), as well as other homemade explosives (HMEs). However, HMTD is an extremely unstable molecule, which makes it difficult to safely obtain and use for the purposes of canine training and testing. To address this challenge, several non-detonable canine training aids have been designed for canine training. Bulk HMTD has a complex headspace, as shown by previous studies. This makes it a difficult odor to mimic and, in turn, makes evaluations and comparison of such training aids essential. In this work, five non-detonable HMTD canine training aids that are either commercially available or under development were evaluated with the goal of determining which most accurately represents the headspace of bulk HMTD. Of the five training aids, two were observed to reasonably mimic HMTD. While the remaining three training aids contained similar headspace components as HMTD, they did not exhibit the complexity of the bulk compound headspace. While none of the tested training aids exactly mirrored the bulk HMTD samples, they may have use in maintenance training when no bulk material is available.