Organic Explosives Research Articles

Potential of Biotechnology in Phytoremediation

The accumulation of toxic substances involving the inorganic and organic contaminants in the soil is a global problem. Status of the World's Soil Resources Report (SWSR) recognized soil pollution as one of the main reasons affecting global soils and the ecosystem services provided by them. However, transgenic approaches utilizing the biodegradation capabilities of microbes and mammals into plants pledge an efficient and eco-friendly approach to renewing the environment. An effective method of phytoremediation involves an enhanced rate of pollutant uptake by the plant, followed by the detoxification of the chemicals absorbed or translocated. It also involves the production of genetically modified herbicide-resistant plants for herbicide remediation and exploits the principles of biotechnology and molecular biology for the introduction and improvement of potentially superior genes into plants. This review discusses the various transgenic approaches involved in the phytoremediation of persistent organic pollutants, metals, metalloids, and explosives. Besides, it also focuses on the limitations of transgenics and provides an insight into the future potential of emerging biotechnological tools and techniques in this field.

Peroxide Based Organic Explosives

In recent years progressively increasing terrorist activities, which use homemade explosives; such as acetone peroxide and other cyclic organic peroxides have led to worldwide awareness by security and defense agencies. Then the development of methodologies for the detection of cyclic organic peroxides have become an urgent need. Until quite recently, most of the current technology in use for trace detection of explosives had been unable to detect these energetic compounds. Differences in physical properties between cyclic organic peroxides is the main barrier for the development of a general method for analysis and detection of the peroxide explosives. In this short review, the most relevant contributions related to preparation, characterization and detection of the most important cyclic organic peroxides have been presented. It also includes few recent investigations about the toxicity and metabolism of some peroxide explosives.

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.

Assembling Hybrid Energetic Materials with Controllable Interfacial Microstructures by Electrospray.

Constructing hybrid energetic materials (HEMs) consisting of nanothermites and organic high explosives is an efficient strategy to regulate the reactivity of energetic composites. To investigate the role of interfacial microstructures in determining the reactivity of HEMs, we employ electrospray, one ramification of electrohydrodynamic atomization, to assemble Al/CuO and hexanitrohexaazaisowurtzitane (CL-20) into composites with various morphologies from different solvent systems. The morphology and compositional information of the assembled clay-like or granular HEMs, which are obtained from ketone, ester, or mixtures of alcohol and ether, are confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The phase transition of CL-20 due to the fast evaporation of charged droplets and insufficient time for recrystallization is studied by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric-differential scanning calorimetry (TG-DSC) is applied to investigate the thermodynamic behaviors and synergistic effect of the nanothermite and high explosive. Enhancements in combustion performance and pressurization characteristics of the as-sprayed HEMs have been observed through open burn tests and pressure cell tests. Granular HEMs show high gas generation and high pressurization rate, while nitrocellulose (NC) fibers existing in the clay-like HEMs would weaken the reactivity to a certain extent. HEMs obtained from the mixture of n-propanol and diethyl ether, in which nano-CL-20 exists as independent particles rather than a matrix, exhibit high gas generation but low pressurization rate. The results indicate that the energy releasing performance of the prepared HEMs can be readily regulated by constructing various interfacial microstructures to satisfy the broad requirements of energy sources.

Potential of Biotechnology in Phytoremediation

The accumulation of toxic substances involving the inorganic and organic contaminants in the soil is a global problem. Status of the World's Soil Resources Report (SWSR) recognized soil pollution as one of the main reasons affecting global soils and the ecosystem services provided by them. However, transgenic approaches utilizing the biodegradation capabilities of microbes and mammals into plants pledge an efficient and eco-friendly approach to renewing the environment. An effective method of phytoremediation involves an enhanced rate of pollutant uptake by the plant, followed by the detoxification of the chemicals absorbed or translocated. It also involves the production of genetically modified herbicide-resistant plants for herbicide remediation and exploits the principles of biotechnology and molecular biology for the introduction and improvement of potentially superior genes into plants. This review discusses the various transgenic approaches involved in the phytoremediation of persistent organic pollutants, metals, metalloids, and explosives. Besides, it also focuses on the limitations of transgenics and provides an insight into the future potential of emerging biotechnological tools and techniques in this field.

Design of Colorimetric Sensor Employing CdSe QDs Decorated Graphene Xerogel for Onsite Visual Detection of TNT

In today's world, extensive use of various organic explosives such as nitroaromatics, nitramines and peroxide can be seen in both military and terrorism. Among the different explosives, 2,4,6-Trinitrotoluene (TNT) and its degraded compound 2,4-Dinitrotoluene (DNT) are the most used energetic material in different legitimately produced explosives and improvised explosive devices (IEDs). The detonation of explosives usually causes damages to the environment, which in turn affects humans’ health and safety. Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. [1,2] In recent years, a number of fluorescent chemosensors/probes have been developed and widely used in chemical sensing of DNT and TNT, especially quantum dots (QDs) and nanoparticles, because of their comprehensive investigation in various applications such as optical sensor, bio-imaging, bio-labeling, biomolecular and NAEs detection. [3] Here, our research efforts are to promote fluorescent Cysteamine capped-CdSe QDs for decorating porous graphene xerogel (GSXS) to design a robust sensor with a new and elegant methodology. Consequently, this sensor can provide good opportunities for visual TNT detection in wearable applications. Graphene oxide (GO), a single monolayer of graphite, has recently attached great scientific attention; besides, the 3D-porous structure of GO has shown impulsive properties, such as large surface areas, high compressibility, ultralow density and adsorption potential. On the other hand, chitosan (CS), alkaline deacetylation of chitin, owned many fascinating properties such as biocompatibility, biodegradability and antimicrobial ability. The 3D-network of GO and CS blend scaffold is expected to have high porosity, surface area, electrochemical properties and high adsorption potential because of hydrogen-bond linking of epoxy groups of GO with the amino group of CS. This nanocomposite could effectively adsorb the QDs and NPs via covalent and non-covalent interactions. Inspired by this top-notch property of GO-CS nanocomposite and the excellent fluorescence property of CdSe QDs, a simple and elegant approach is introduced to design a colorimetric sensor based on QDs decorated graphene xerogel (QD-GSXS), also called GO-CS nanocomposite. Its dual benefit can provide a novel path of sensitive and selective sensing for chemical and biological applications. The preparation of this fluorescent QD-GSXS nanosensor would be a challenge of relevance because of the fluorescent material is usually quenched by graphene. [4] So, this work aims to successfully synthesis fluorescent QD-GSXS nanosensor and exhibits its application for on-site and visual detection of TNT via the formation of the Meisenheimer complex. Herein firstly, we synthesized porous graphene xerogels wrapped with an optimized mass ratio of chitosan. This xerogel surface is further decorated with highly fluorescent Cysteamine capped-CdSe QDs. These composite were characterized using XRD, FE-SEM, FTIR, Raman, BET, UV-Vis and fluorescence spectroscopy. This spongy fluorescent QD-GSXS nanosensor probe was employed for the sensitive and selective detection of TNT. The sensing mechanism is further stabilized via Time-correlated Single Photon Counting (TCSPC) measurement and with the frontier-molecular energy level analysis, calculated by Density-Functional-Theory (DFT). More importantly, we further demonstrated the utility of this designed nanosensor probe as on-site visual TNT sensor by observing a rapid fluorescence change in optical images captured under the illumination of Green Fluorescent Protein (GFP). The design chemosensor showed several advantages, including good selectivity, excellent stability and having linearity with the concentration of TNT. Such a simple colorimetric sensor allows the visual detection of TNT at µM level without any sophisticated instrument. In addition, CdSe-NH2 QDs were also exhibited sensing with DNT and TNT in solution with LOD 18.2 and 9.7 µM, respectively. Considering their structure versatility and design flexibility, we anticipate that our efforts were to combine the electron-donor unit, cystamine capped-CdSe QDs, with an intrinsic porosity of GSXS and make it functional for NAEs detection. This novel and elegant approach gives a new direction to make a prototype chemosensor for visual detection of different NAEs with the advantages of simplicity, ease of operation and high sensitivity. However, there is a wide scope to increase the sensitivity further. This approach will also benefit future research on developing fluorescent hybrid nanosensors based on fluorescent nanoparticles and quantum dots for various chemical and biological applications.

General Surface-Enhanced Raman Spectroscopy Method for Actively Capturing Target Molecules in Small Gaps.

Over the past decade, many efforts have been devoted to designing and fabricating substrates for surface-enhanced Raman spectroscopy (SERS) with abundant hot spots to improve the sensitivity of detection. However, there have been many difficulties involved in causing molecules to enter hot spots actively or effectively. Here, we report a general SERS method for actively capturing target molecules in small gaps (hot spots) by constructing a nanocapillary pumping model. The ubiquity of hot spots and the inevitability of molecules entering them lights up all the hot spots and makes them effective. This general method can realize the highly sensitive detection of different types of molecules, including organic pollutants, drugs, poisons, toxins, pesticide residues, dyes, antibiotics, amino acids, antitumor drugs, explosives, and plasticizers. Additionally, in the dynamic detection process, an efficient and stable signal can be maintained for 1-2 min, which increases the practicality and operability of this method. Moreover, a dynamic detection process like this corresponds to the processes of material transformation in some organisms, so the method can be used to monitor transformation processes such as the death of a single cell caused by photothermal stimulation. Our method provides a novel pathway for generating hot spots that actively attract target molecules, and it can achieve general ultratrace detection of diverse substances and be applied to the study of cell behaviors in biological systems.

Recent advances in stable isotope ratio analysis of common explosives

炸药的深度比对与溯源对于爆炸案事件的侦破具有重大意义,以不同地域来源的原料或不同生产工艺生产的炸药,其组成元素的稳定同位素比值具有差异,因而稳定同位素比值可作为炸药深度比对与溯源的重要指标。稳定同位素比值质谱法(IRMS)作为一种高精度的稳定同位素比值测量手段,已逐渐发展成熟,与元素分析仪、气相色谱仪、液相色谱仪等仪器联用,在食品安全、环境保护、法庭科学等领域应用广泛。IRMS在炸药比对与溯源上亦发挥了重要作用,自1975年IRMS被应用于区分不同国家生产的三硝基甲苯(TNT)以来,IRMS已成功用于多种炸药的分析。但目前尚未见有文献系统地总结常见炸药的稳定同位素比值分析研究进展。该文介绍了稳定同位素比值分析的相关原理、仪器组成及特点,分别总结了硝酸铵、黑火药、TNT、太恩、黑索金等常见炸药的稳定同位素比值分析方法,汇总了文献报道的不同国家生产的硝酸铵、黑火药、TNT等炸药的稳定同位素比值。文章就不同炸药的稳定同位素比值差异、炸药生产、存储过程中相关因素对同位素比值的影响,爆炸前后稳定同位素比值的变化情况等内容进行了分析。本文还指出了目前炸药的稳定同位素比值分析研究中存在的问题,对可能的解决办法进行了讨论,对未来的发展方向提出了建议。

Fast energy release from reactive materials under shock compression

Metal-based reactive nanomaterials (RNMs) can produce two to three times more energy than conventional organic explosives, but the exothermic reactions, which ordinarily require diffusive mixing of separated fuel and oxidizer components, are too slow and do not generate enough gas to produce detonations. Here, we studied shock initiation of 4Al/Bi2O3 and 4Al/BiF3 RNMs produced by arrested reactive milling. Initiated by a 3 km/s impact, which approximates a powerful detonation, fast energy release produced 3200 K temperatures. In the fluoride, a rapid volume increase was also observed. The shock-induced energy release was orders of magnitude faster than when the RNM was heated. Although these RNM powders by themselves likely cannot produce detonations, our results suggest that used as additives in detonating systems, they might significantly boost the energy of chemical explosives.

Engineering the Microstructure and Morphology of Explosive Films via Control of Interfacial Energy.

Physical vapor deposition of organic explosives enables growth of polycrystalline films with a unique microstructure and morphology compared to the bulk material. This study demonstrates the ability to control crystal orientation and porosity in pentaerythritol tetranitrate films by varying the interfacial energy between the substrate and the vapor-deposited explosive. Variation in density, porosity, surface roughness, and optical properties is achieved in the explosive film, with significant implications for initiation sensitivity and detonation performance of the explosive material. Various surface science techniques, including angle-resolved X-ray photoelectron spectroscopy and multiliquid contact angle analysis, are utilized to characterize interfacial characteristics between the substrate and explosive film. Optical microscopy and scanning electron microscopy of pentaerythritol tetranitrate surfaces and fracture cross sections illustrate the difference in morphology evolution and the microstructure achieved through surface energy modification. X-ray diffraction studies with the Tilt-A-Whirl three-dimensional pole figure rendering and texture analysis software suite reveal that high surface energy substrates result in a preferred (110) out-of-plane orientation of pentaerythritol tetranitrate crystallites and denser films. Low surface energy substrates create more randomly textured pentaerythritol tetranitrate and lead to nanoscale porosity and lower density films. This work furthers the scientific basis for interfacial engineering of polycrystalline organic explosive films through control of surface energy, enabling future study of dynamic and reactive detonative phenomena at the microscale. Results of this study also have potential applications to active pharmaceutical ingredients, stimuli-responsive polymer films, organic thin film transistors, and other areas.

Identification and analysis of organic explosives from post-blast debris by nuclear magnetic resonance

The growing threat of terrorism has triggered an urgent need to find effective ways to improve the analysis of explosives. This will aid forensic scientists in analysing the post-blast debris, which in turn helps the law enforcement agencies to frame suitable regulations. Analysis of post-blast debris is challenging as it hosts a massive amount of complexity. There are various techniques reported till date such as mass spectrometry, gas chromatography, high-performance liquid chromatography, Fourier transform infrared spectroscopy, and Raman spectroscopy for the analysis of post-blast residues. However, none of them has been able to identify the structural composition of the explosives. The current research study focuses on identifying the structural composition of the explosives from the post-blast debris using the nuclear magnetic resonance (NMR) technology. The post-blast analytes were extracted from soil samples, cleaned by the solid phase extraction (SPE) method and were rapidly analysed by the nuclear magnetic resonance spectrometer. This paper reports the identification of nitro organic explosives such as pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT) and 2,4,6-trinitrophenylmethylnitramine (tetryl) in post-blast debris by 400 MHz nuclear magnetic resonance spectrometer.

Trace multi-class organic explosives analysis in complex matrices enabled using LEGO®-inspired clickable 3D-printed solid phase extraction block arrays.

The development of a new, lower cost method for trace explosives recovery from complex samples is presented using miniaturised, click-together and leak-free 3D-printed solid phase extraction (SPE) blocks. For the first time, a large selection of ten commercially available 3D printing materials were comprehensively evaluated for practical, flexible and multiplexed SPE using stereolithography (SLA), PolyJet and fused deposition modelling (FDM) technologies. Miniaturised single-piece, connectable and leak-free block housings inspired by Lego® were 3D-printed in a methacrylate-based resin, which was found to be most stable under different aqueous/organic solvent and pH conditions, using a cost-effective benchtop SLA printer. Using a tapered SPE bed format, frit-free packing of multiple different commercially available sorbent particles was also possible. Coupled SPE blocks were then shown to offer efficient analyte enrichment and a potentially new approach to improve the stability of recovered analytes in the field when stored on the sorbent, rather than in wet swabs. Performance was measured using liquid chromatography-high resolution mass spectrometry and was better, or similar, to commercially available coupled SPE cartridges, with respect to recovery, precision, matrix effects, linearity and range, for a selection of 13 peroxides, nitramines, nitrate esters and nitroaromatics. Mean % recoveries from dried blood, oil residue and soil matrices were 79 ± 24%, 71 ± 16% and 76 ± 24%, respectively. Excellent detection limits between 60 fg for 3,5-dinitroaniline to 154 pg for nitroglycerin were also achieved across all matrices. To our knowledge, this represents the first application of 3D printing to SPE of so many organic compounds in complex samples. Its introduction into this forensic method offered a low-cost, 'on-demand' solution for selective extraction of explosives, enhanced flexibility for multiplexing/design alteration and potential application at-scene.

Solution-processed self-assemble engineering PDI derivative polymorphisms with optoelectrical property tuning in organic field-effect transistors

Abstract The crystal polymorphism study leads to an explosion of science research, related to many fields, such as organic semiconductors, pharmaceuticals, pigments, food, and explosives. Two different crystal phases of a perylene diimide derivative (4FPEPTC) have been prepared via a simple and efficient solution method. Via changing the concentration of the solution, we observed the polymorphisms clearly, wire-shape (α phase) and ribbon-like (β phase) crystals differed in the stacking mode and short-contacts. Moreover, the as-prepared n-channel microcrystal-based devices demonstrated distinct electron mobilities that of α phase architecture higher than β phase structure and obvious photoresponse discrepancy. Theoretical calculations further confirmed this phenomena, which help us to understand the structure-property relationship in this crystal polymorph. Our study indicates that the investigation of polymorphisms could be considered as a very useful method to realize functional property modulation and benefits the development of organic (opto)electronics.

The Effect of Metal Film Thickness on Ignition of Organic Explosives with a Laser Pulse.

The results of numerical ignition simulation of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) by aluminium (Al) and molybdenum (Mo) films heated by nanosecond laser pulses in a three-layer system: glass–metal–explosive material (EM) are presented. Influence of metal film thickness on the time of EM ignition delay was considered. A non-linier dependence of time of delay of ignition of EM from thickness of a metal film is shown. The greatest critical thicknesses of Al and Mo metallic films at which ignition of EM is still possible were determined. It was established that the greater the thickness of the metal film and heat resistance of EM, the greater the heat reserve needed in EM ignition film. It was established that the ignition delay time of EM increases in the sequence of PETN, RDX, HMX and TATB.

A mechanical stability enhanced luminescence lanthanide MOF test strip encapsulated with polymer net for detecting picric acid and macrodantin.

The improper use of organic explosives and antibiotics have brought serious threats to the public health and the environmental safety, exploiting cost-effective and handy luminescent sensors with water stability and high selectivity in monitoring and detecting these hazardous substances are of utmost importance. Herein, we developed a simple yet powerful luminescent test strip sensor in a facile way. As for fabricating this test strip, the filter paper used for filtering lanthanide MOF (Ln-MOF) of [Tb(HIP)(H2O)5]·(H2O)·(HIP)1/2 (Tb-HIP, where HIP is 5-hydroxyisophthalate) powders was firstly recycled, and encapsulated with poly(methyl methacrylate) (PMMA) polymer net. The as-fabricated Tb-HIP test strips exhibit enhanced mechanical stability than the un-encapsulated ones, and show characteristic green emission of Tb3+. These test strips can behave as promising highly selective luminescent probes for picric acid (PA) and macrodantin (MDT) even existence of relevant potentially competing analytes. The detection limit for PA is 0.26μM, and for MDT is 0.21μM. In addition, the sensors can be successfully applied to detect PA in the river water samples as well as MDT in serum samples with satisfactory results. More importantly, the Tb-HIP test strips are highly efficient, recyclable luminescence sensors to detect PA and MDT.

Utilizing Surface Acoustic Wave Nebulization (SAWN) for the Rapid and Sensitive Ambient Ionization Mass Spectrometric Analysis of Organic Explosives

When considering incident investigations and security checks focused on energetic materials, there is an ongoing need for rapid, on-scene chemical identification. Currently applied methods are not capable of meeting all requirements, and hence, portable mass spectrometry is an interesting alternative although many instrumental challenges still exist. To be able to analyze explosives with mass spectrometry outside the traditional laboratory, suitable ambient ionization methods need to be developed. Ideally such methods are also easily implemented in the field requiring limited to no power sources, gas supplies, flow controllers, and heating devices. For this reason, the potential of SAWN (surface acoustic wave nebulization) for the ambient ionization and subsequent mass spectrometric (MS) analysis of organic explosives was investigated in this study. Excellent sensitivity was observed for nitrate-based organic explosives when operating the MS in negative mode. No dominant adduct peaks were observed for the peroxides TATP and HMTD with SAWN-MS in positive mode. The MS spectra indicate extensive fragmentation of the peroxide explosives even under the mild ionization conditions provided by SAWN. The potential of SAWN-MS was demonstrated with the correct identification of nitrate-based organic explosives in pre- and post-explosion case samples in only a fraction of the time and effort required for the regular laboratory analysis. Results show that SAWN-MS can convincingly identify intact organic energetic compounds and mixtures but that sensitivity is not always sufficient to detect traces of explosives in post-explosion residues.

Effect of Decomposition of CuO Film on Ignition of Organic Explosives by a Laser Pulse

AbstractThis work presents experimental results of the PETN ignition in a three‐layer system: glass – copper oxide ( ) – explosive materials (EM) and results of numerical simulations of the ignition of PETN, RDX, HMX, and TATB with a film heated by a YLS‐150 fiber laser with a pulse duration of . In the numerical simulations, the endothermic reaction of decomposition of the film and decomposition reaction of EM were taken into account. It has been established that the endothermic effect of the decomposition reaction increases the dynamic ignition delay time of EM. The expression for an estimation of width of a reaction layer in EM at heating by a constant heat stream is obtained. Calculations have shown that the dynamic threshold of ignition of organic explosives by laser pulse in a three‐layer system (glass – – EM) has a minimum for the thickness of the copper oxide film of . The density of the critical ignition energy of an explosive laser pulse increases in the sequence of PETN, RDX, HMX, and TATB. The calculated dependence of the PETN dynamic ignition delay time on the thickness of the film is consistent with the experimental data.

Energetic Metal-Organic Frameworks Incorporating NH3OH+ for New High-Energy-Density Materials.

Energetic metal-organic frameworks (E-MOFs) have witnessed increasing development over the past several years. However, as a highly energetic cation, NH3OH+ has never been explored to construct transition-metal-based E-MOFs. Herein, we report the first examples of NH3OH+-containing E-MOFs with bis(tetrazole)methane (H2btm) as a ligand and copper and manganese as central metal ions, [(NH3OH)2(Cu(btm)2)]n and [(NH3OH)2(Mn(btm)2)]n. Crystal structure determinations reveal that both E-MOFs show two-dimensional layered structures. Experimental results suggest that they have high thermal decomposition temperatures (>200 °C). Among them, Cu-based E-MOFs possesses outstanding thermal stability (Tdec = 230.3 °C), which surpasses those of known NH3OH+-containing compounds. They also have high energy density; in particular, the Cu-based E-MOF affords a high heat of combustion (11447 kJ kg-1) and high heat of detonation (713.8 kJ mol-1) beyond the most powerful organic explosives in use today. Additionally, the two E-MOFs show completely different sensitivity properties: the Mn-based E-MOF is an insensitive high-energy-density material (IS > 40 J; FS > 360 N; EDS > 20 J), while the Cu-based E-MOF can be classified as a sensitive energetic material (IS = 13 J; FS = 216 N; EDS = 10.25 J), demonstrating their diverse applications in different fields. Our research proposes a unique class of high-energy-density materials.

Improved determination of femtogram-level organic explosives in multiple matrices using dual-sorbent solid phase extraction and liquid chromatography-high resolution accurate mass spectrometry

Identification and trace quantification of multiple explosives residues, their precursors and transformation products in complex samples remains very challenging. For solid phase extraction (SPE) and liquid chromatography-high resolution accurate mass spectrometry-based methods (LC-HRMS), interferences from co-extracted matrix components can significantly affect recovery during extraction and/or detector signal. The aim of this work was to develop a new, improved and more generalisable extraction approach to trace explosives analysis in a range of matrices using dual-sorbent SPE with LC-HRMS. Recoveries of 44 organic explosives from model solutions were optimised and compared for seven different sorbents (Oasis HLB, HyperSep Retain PEP and Isolute ENV+, HyperSep SAX, HyperSep NH2, Strata Alumina-N and Bond Elut CN). On average, Oasis HLB and Isolute ENV+ yielded the best recoveries (>80%). For three sorbents, mean recoveries remained ≤1%, which made them potentially suitable for matrix removal when used in series with more analyte-selective sorbents. To evaluate matrix effects, a range of aqueous (river- and wastewater), solid (soil), dirty (road sign swabs), oily (oven hood swabs) and biological (dried blood) samples were selected based on complexity and forensic relevance. With the exception of river water, matrix effects were lowest using dual-sorbent SPE, with little/no compromise in recovery. Quantitative method performance assessment is presented for 14 selected explosives, representative of different classes, molecular weights and volatilities, and across three different matrices (i.e. untreated wastewater, cooking oil residues and dried blood). Limits of detection improved by ∼10-fold over a single sorbent approach, enabling low fg sensitivity in many cases. Finally, application of the method to untreated wastewater enabled detection of new explosives traces for the first time, which could be used to help identify clandestine manufacture or sources of environmental toxicity. This approach offered a versatile solution to sample preparation for robust and highly sensitive detection/quantification of large numbers of explosives residues in a range of complex sample types.

Targeted and non-targeted forensic profiling of black powder substitutes and gunshot residue using gradient ion chromatography – high resolution mass spectrometry (IC-HRMS)

A novel and simplified gradient IC-HRMS approach is presented in this work for forensic profiling of ionic energetic material residues, including low-order explosives and gunshot residue (GSR). This new method incorporated ethanolic eluents to facilitate direct coupling of IC and HRMS without auxiliary post-column infusion pumps that are traditionally used to assist with gas phase transfer. Ethanolic eluents also enabled better integration with an in-service protocol for direct analysis of high-order organic explosives by IC-HRMS, without requiring solvent exchange before injection. Excellent method performance was achieved, enabling both full scan qualitative and quantitative analysis, as required. In particular, linearity for 19 targeted compounds yielded R2 > 0.99 across several orders of magnitude, with trace analysis possible at the low-mid pg level. Reproducibility and mass accuracies were also excellent, with peak area %RSDs <10%, tR %RSDs <0.4% and δm/z < 3 ppm. The method was applied to targeted analysis of latent fingermarks and swabbed hand sweat samples to determine contact with a black-powder substitute containing nitrate, benzoate and perchlorate. When combined with principal component analysis (PCA), the effect of time since handling on recorded signals could be interpreted further in order to support forensic investigations. In a second, non-targeted application, PCA using full scan IC-HRMS data enabled classification of GSR from three different types of ammunition. An additional 20 markers of GSR were tentatively identified in silico, in addition to the 15 anions detected during targeted analysis. This new approach therefore streamlines and adds consistency and flexibility to forensic analysis of ionic energetic material. Furthermore, it also has implications for targeted, non-targeted and suspect screening applications in other fields by expanding the separation space to low molecular weight inorganic and organic anions.