Detection Of Explosive Residues Research Articles

Research progress in chemometrics in the detection of explosive residues

Research progress in chemometrics in the detection of explosive residues

Detection of Explosive Residues Using Nanomaterial-based Sensors: A Review

Abstract: Due to the recent rise in explosive-based terrorism and ecological issues, the invention of good capacity detectors for the identification of explosives has emerged as one of the major thirsts in the scientific community. Due to their unique optical and electrical properties, nanocomposites can meet all of the prerequisites for developing preferential, responsive, easy, and cost-effective sensor nodes for the sensing of various explosives. This study primarily throws light on current developments in explosives detection using nanomaterial-based sensors. In particular, it describes how quantum dots, carbon nanomaterials, monometallic nanomaterials, and bimetallic nanomaterials have been used to detect explosives optically and electrochemically. The accurate and consistent features of the nanomaterials, including their synthesis, the explosive detection technique, and the analytical facets, are all thoroughly examined.

An Excitation Navigating Energy Migration of Lanthanide Ions in Upconversion Nanoparticles.

Upconversion nanoparticles (UCNPs) doped with lanthanide ions that possess ladder-like energy levels can give out multiple emissions at specific ultra-violet or visible wavelengths irrespective of excitation light. However, precisely controlling energy migration processes between different energy levels of the same lanthanide ion to generate switchable emissions remains elusive. Herein, a novel dumbbell-shaped UCNP is reported with upconverted red emission switched to green emission when excitation wavelength changed from 980 to 808 nm. The sensitizer Yb ions are doped with activator Er ions and energy modulator Mn ions in NaYF4 core nanocrystal coated with an inner NaYF4 :Yb shell to generate red emission after harvesting 980 nm excitation light, while an outer NaNdF4 :Yb shell is coated to form a dumbbell shape to generate green emission upon 808 nm excitation. Such specially designed UCNPs with switchable green and red emissions are further explored for imaging of latent fingerprint and detection of explosive residues in the fingerprint simultaneously. This work suggests a novel research interest in fine-tuning of upconversion emissions through precisely controlling energy migration processes of the same lanthanide activator ion. Furthermore, use of these nanoparticles in other applications such as simultaneous dual-color imaging or orthogonal bidirectional photoactivation can be explored.

β-Octaalkoxyporphyrins: Versatile fluorometric sensors towards nitrated explosives

Real time detection of explosive residues is important to mitigate increasing security threats. Therefore, systematic studies are essential to optimize the performance of sensors. In this work, we have explored β-octamethoxyporphyrin and β-octabutoxyporphyrin to evaluate the effect of alkoxy groups in solution and in vapor phase sensing of nitrated explosives. Our systematic studies revealed a marked difference in sensitivity of these free-base porphyrins in solution state and vapor phase sensing of nitrated explosives simply by modulation of alkyl chain lengths. Alkoxyporphyrins exhibit very good sensitivity towards not only nitro aromatics but also alkyl nitro explosive taggants compared to β-octaethylporphyrin. Therefore, alkoxyporphyrins may act as versatile fluorescence turn-off based chemical sensors for nitrated explosives.

Diaminocyclohexane-Functionalized/Thioglycolic Acid-Modified Gold Nanoparticle-Based Colorimetric Sensing of Trinitrotoluene and Tetryl.

Detection of explosive residues in soil and postblast debris is an important issue in sensor design for environmental and criminological purposes. An easy-to-use and low-cost gold nanoparticle (AuNP)-based colorimetric sensor was developed for the determination of nitroaromatic explosives, i.e., trinitrotoluene (TNT) and tetryl, capable of analyte detection at picomolar (pM) levels. The sensor nanoparticles were synthesized by functionalizing the negatively charged thioglycolic acid (TGA)-modified AuNPs with positively charged (±)- trans-1,2-diaminocyclohexane (DACH) at a carefully calculated pH. The working principle of the sensor is charge-transfer (CT) interaction between the electron-rich free amino (-NH2) group of DACH and the electron-deficient -NO2 groups of TNT/tetryl, added to possible nanoparticle agglomerization via electrostatic interaction of TNT-Meisenheimer anions with more than one cationic DACH-modified AuNP. The limit of detection (LOD) and limit of quantification (LOQ) of the sensor were 1.76 pM and 5.87 pM for TNT and 1.74 pM and 5.80 pM for tetryl, respectively. TNT, tetryl, and tetrytol, extracted from a nitroaromatic explosive-contaminated soil sample, were determined with the proposed sensor, yielding good recoveries. The sensor could be selectively applied to various mixtures of TNT with common energetic materials such as RDX, HMX, and PETN. Additionally, common soil ions (Cl-, NO3-, SO42-, K+, Mg2+, Ca2+, Cu2+, Fe2+, Fe3+, and Al3+) as well as detergents, sugar, sweeteners, acetylsalicylic acid (aspirin), caffeine, and paracetamol-based painkiller drugs, which may be used as camouflage materials for explosives, either had no adverse effects or removable interferences on the detection method. The developed method was statistically validated against a GC-MS literature method.

Influence of metal substrates on the detection of explosive residues with laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy is a promising approach for explosive residue detection, but several limitations to its widespread use remain. One issue is that the emission spectra of the residues are dependent on the substrate composition because some of the substrate is usually entrained in the laser-induced plasma and the laser-material interaction can be significantly affected by the substrate type. Here, we have demonstrated that despite the strong spectral variation in cyclotrimethylenetrinitramine (RDX) residues applied to various metal substrates, classification of the RDX residue independent of substrate type is feasible. Several approaches to improving the chemometric models based on partial least squares discriminant analysis (PLS-DA) have been described: classifying the RDX residue spectra together in one class independent of substrate, using selected emission intensities and ratios to increase the true positive rate (TPR) and decrease the false positive rate (FPR), and fusing the results from two PLS-DA models generated using the full broadband spectra and selected intensities and ratios. The combination of these approaches resulted in a TPR of 97.5% and a FPR of 1.0% for RDX classification on metal substrates.

Isobutane Chemical Ionization Mass Spectrographic Examination of Explosives

Abstract The detection of explosive residues in debris is difficult because of the thermal instability of many explosives along with the high sensitivity requirements of the analyses. The isobutane chemical ionization (CI) mass spectra of common civilian and military explosives were obtained under different instrumental parameters. The intent of the study was to determine the feasibility of applying CI to residue detection. The CI spectra of the explosives 1,3,5-trinitro-1,3,5-triazocydohexane, 1,3,5,7-tetraazocyclooctane, and pentaerythritol tetranitrate were shown to be particularly sensitive to the conditions of source temperature and reagent gas pressure. These parameters were adjusted to yield the least complex CI spectra for the explosives studied. The simplicity of the CI spectra obtained makes it a feasible technique for detecting explosive residues in the presence of extraneous materials found in the acetone extracts of debris material. Placement of the extract into the direct probe of the CI mass spectrometer eliminates the need for prior chromatographic treatment of the extract and would optimize the high sensitivity of the CI technique.