Nitroaromatic Explosive Compounds Research Articles

An Adenine‐Based Chromone‐Coupled ‘Off‐On‐Off’ Fluorogenic Dyad for Cascade Detection of Zn2+ and HSO₄− Ions or Zn2+ Ions and Picric Acid

AbstractA chromone‐coupled adenine‐based fluorogenic chemosensor (BD1) has been introduced for cascade detection of Zn2+ and HSO4−ions or Zn2+ and picric acid (PA) based on the fluorescence ‘OFF‐ON‐OFF’ mechanism. A momentous fluorescence improvement has been observed due to the accumulation of Zn2+ ions in the BD1 solution because of the formation of the Zn2+ chelated BD1 complex. A cyan color fluorescence enhancement is visible under the exposure of a 365 nm UV lamp, which is also manifested in the CIE diagram. The detection limit of our developed sensor BD1 and Zn2+−BD1 complex towards the identification of Zn2+ and HSO4− ions are in the nM and μM range, respectively, in the solution phase. Among the several explosive nitroaromatic compounds (NACs), only PA quenches the fluorescence of the Zn2+ chelated BD1 complex, and the nature of quenching is both static and dynamic. A paper strips‐based test kit experiment is performed for on‐spot identification of Zn2+ ions and PA. Based on these chemically encoded inputs and the fluorescence intensity as optical output, we have constructed an INHIBIT molecular logic circuit. The present report evokes a new approach for the development of new chemosensors from bioinspired materials such as adenine, a purine nucleobase.

Selective detection of explosive nitro-aromatic compounds using the 2D organic nanosheets (2DONs) synthesize via 2D click chemistry directed by ultrasonication

Recent advancements in click chemistry have made it an effective method for quickly and easily assembling extremely stable nanomaterial assemblies onto surfaces. Therefore, a new class of fluorescent sensor utilizing two-dimensional organic nanosheets (2DONs) for the selective sensing of 2,4-dinitrophenylhydrazine (2,4-DNPH) has been proposed by using the click chemistry directed by the probe ultrasonication method (CCDPS) which is driven by the π-π stacking interactions with the aid of DMF solvent. Prolonged human exposure to 2, 4-DNPH has been associated with various detrimental health consequences, including skin conditions, liver issues, and disturbances to the central nervous and cardiovascular systems. Fluorescence titration tests with nanomolar scale limit of detection (LOD, 100 nM or 0.1 μM) and limit of quantification (LOQ, 0.4 μM) for 2,4-DNPH showed fluorescence quenching reactions and excellent reversibility. Additionally, zeta potential and UV-absorption spectroscopy were used to validate the interaction and binding characteristics of 2D ONs with 2,4-DNPH. In contrast to the widely reported ground-state charge transfer or FRET-based probes for nitroaromatics detection, the signal response for 2,4-DNPH was achieved by a strong inner filter effect with the combination of FRET (IFE-FRET).

Facile construction of an anthracene-decorated highly luminescent coordination polymer for the selective detection of explosive nitroaromatics and the mutagenic pollutant TNP.

Explosive nitroaromatic compounds (epNACs) are a group of chemicals that have caused significant human casualties through terrorist attacks and they also pose health risks. For the benefit of homeland security and environmental health, there is room for advancing research on the precise detection of epNACs. Coordination polymers (CPs) successfully serve this purpose because of their binding abilities and quenching capabilities. In this regard, a one-dimensional (1D) CP [Zn(bdc)(avp)2(H2O)]n (1; H2bdc = 1,4-benzenedicarboxylic acid and avp = 4-[2-(9-anthryl)vinyl]pyridine) was synthesized, which remarkably demonstrated extremely efficient ratiometric and selective sensing capacity toward epNACs and the mutagenic pollutant 2,4,6-trinitrophenol (TNP) with a quick response. Density functional theory (DFT) calculations provided a thorough analysis of the mechanistic routes behind the quenching reaction. Herein, geometrically accessible interaction sites were strategically decorated using anthracene moieties, allowing the quick and precise detection of explosive nitro derivatives and the carcinogenic pollutant TNP with increased sensitivity.

Synthesis of two-dimensional bismuth molybdenum oxide (2D-BMO) nanosheets and their application as fluorescent probes for the detection of explosive nitroaromatic compounds

2D-BMO fluorescent nanosheets were synthesized using a solvothermal method followed by probe sonication.

Voltammetric Detection of Explosive Nitroaromatic Compounds Using Boron-Doped Carbon Nanowall Electrodes

Nitroaromatic highly energetic explosive compounds were widely used during the I and II World Wars. Some of them, like 2,4,6-trinitrotoluene (TNT), are still used in military munitions or in industrial applications i.e., underwater blasting, mining, deep well or dye production. The worldwide use of nitroaromatic compounds led to widespread pollution of the environment causing a danger to living organisms due to their high toxicity and possible carcinogenicity. The most commonly used techniques for the detection of explosive nitroaromatics are high-performance liquid chromatography or high-resolution gas chromatography coupled with different detectors like mass spectrometers. Both methods require: expensive instrumentation, complex sample preparation which is crucial to analysis, and well-trained staff to perform the experiments. Therefore it is difficult to implement chromatography in the field. Electrochemical sensing is emerging as a fast, sensitive and relatively simple technique for detecting explosive materials. To date, various materials have been used as working electrodes for this purpose, however, carbon materials are particularly promising [1-2]. Among carbonaceous materials, boron-doped carbon nanowall (B:CNW) electrodes are particularly attractive for the sensitive and rapid detection of nitro-based compounds [3] due to the high content of sp2 phase, wide electrochemical working potential window (from -1.6 V to 1.2 V in 0.5 M KCl) and high values of heterogeneous electron transfer rate constant.In this work, we present electrochemical detection of chosen nitroaromatic explosive compounds like TNT on boron-doped carbon nanowall electrodes in aqueous solutions using voltammetric electrochemical techniques (differential pulse voltammetry, square-wave voltammetry, cyclic voltammetry). B:CNW electrodes were obtained using microwave plasma-assisted chemical vapour deposition in a one-step growth process. B:CNW electrode show enhanced electrocatalytic activity towards nitro moieties attached to aromatic rings, resulting in improved sensitivity toward detecting these groups. Hence, it is an attractive nanocarbon surface for nitroaromatic compound determination.

One-Dimensional Coordinated Polymers of Tetraphenylethene Pyridine and Copper-Iodide for Fluorescence Detection of Nitroaromatic Explosives.

The spatial arrangement of molecules plays a crucial role in determining the macroscopic properties of functional materials. Coordinated polymers (CPs) formed by self-assembly of organic isomeric ligands and metals offer unique performance characteristics. In this study, we present the investigation of a one-dimensional CP, named CIT-E, composed of tetraphenylethene pyridine derivative (TPE-2by-2-E) ligands and cuprous iodide. The resulting CP exhibits a one-dimensional bead chain structure with exceptional thermal and chemical stability. By leveraging the competitive absorption between CIT-E and the explosive analog 2,4-dinitroaniline, we achieve detection of the explosive through changes in the absorption intensity of the excitation light source and subsequent fluorescence response. The CP demonstrates high selectivity and anti-interference ability in detecting 2,4-dinitroaniline in aqueous solution, with a detection linear range of 0.1 μM to 300 μM and a detection limit of 0.05 μM, surpassing the national third-level emission standard. These findings highlight the potential of CP CIT-E as a promising material for the detection of explosive nitroaromatic compounds.

Photoluminescent pyrene-based ionic liquid derived ratiometric organo nanosensor for rapid and selective detection of picric acid

Due to the rising menace of illicit actions and pollution aroused by explosive nitroaromatic compounds (NACs), the growth of an adept sensor for detecting these NACs is highly essential. Herein, in this communication, a photoluminescent IL-assimilated group of uniform materials based on organic salt (GUMBOS) and nano-GUMBOS has been fabricated by integrating pyrene butyrate with a quaternary phosphonium IL (PbIL) via a simple ion exchange process. Neat PbIL shows a bright cyan color photoluminescence under a 365 nm UV lamp irradiation and is employed as photoluminescence security ink and picric acid (PA) detection among the tested NACs. By simple reprecipitation method, we have developed water-suspended crystalline pyrene assimilated nanoparticles, nPbIL, characterized by various analytical techniques. The PbIL-derived water-suspended nanomaterials, nPbIL, display a robust cyan color excimer-like emission, which turns blue (monomeric) due to adding PA over the other related NACs. This ratiometric cyan to blue photoluminesce change is due to the displacement of the anionic pyrene moiety of the nPbIL by the picrate anion. The fabricated organo nanosensor is enormously discerning and responsive towards PA with a detection limit of 0.77 nM and is found to be superior to many available in the literature. Additionally, a fluorogenic paper strip-based test kit experiment has been demonstrated to detect and quantify PA selectively in aqueous solvents amongst the other tested NACs. The present contribution evokes a novel approach to developing different IL-based chemosensors for detecting and quantifying various target analytes.

Phthalimide‐Based Off‐On‐Off Fluorosensor for Cascade Detection of Cyanide Ions and Picric Acid

AbstractNovel methods that can be utilized to identify and detect harmful environmental pollutants still need to be proposed. This article describes the effective design and development of a turn‐on photoluminescence probe, T1 [(E)‐5‐((2‐hydroxybenzylidene) amino) isoindoline‐1, 3‐dione], which is selective and sensitive towards CN− ions having detection limit nM to μM range. When exposed to CN− ions, Probe T1 displays a strong fluorescence response under a 365 nm UV light irradiation with a noticeable low to high intense cyan color photoluminescence visible to the naked eye. For the practical utility of the present probe T1, a paper strips‐based test kit experiment has been demonstrated as a portable and displayable photonic device for on‐site detection of CN− ions. Furthermore, the T1‐CN− adduct has been applied for detecting explosive nitroaromatic compounds, especially PA, based on the photoluminescence quenching mechanism. Using CN− ions, and PA as chemically encoded inputs and corresponding optical output, a molecular logic gate has been constructed. Further, probe T1 has been employed as a bio‐analytical tool to map intercellular CN− ions in live cells. This study invokes a novel approach for designing and developing efficient and selective sensors employing well‐known fluorescent probes as signaling units with prior photophysical knowledge.

Real-Time Monitoring and 3D Mapping of Trace Vapors of Explosive Nitroaromatic Compounds at Room Temperature by Gas-Phase Scanning Electrochemical Microscopy.

Development of sensing technologies for trace vapors of nitroaromatic compounds (NACs) is highly desired due to the toxic and explosive nature of the target molecules. Here, a NAC sensor based on a membraneless ionic liquid electrochemical cell was developed and applied for room-temperature trace vapor detection. Submicrometer working electrode dimensions yielded maximized portability and cost efficiency and extremely short time scales for molecular identification. The nanoprobe exhibited detection limitscomparable to those of state-of-the-art NAC sensors. The most noteworthy feature was the fast response to trace vapors, allowing for real-time detection of NACs without sample pretreatment. The pulled capillary form factor of the developed sensor enabled its application as tip electrodes in gas-phase scanning electrochemical microscopy (SECM). With the degree of freedom in three dimensions, mapping of the differential vapor pressure of NACs was possible, leading to potential application of the probe in sniffing out the source of explosive gas dissemination.

A 4-aminophthalimide derive smart molecule for sequential detection of aluminum ions and picric acid

A fluorosensor derived from 4-aminophthalimide,((E)-5-((2-hydroxybenzylidene) amino) isoindoline-1, 3-dione, HID) working with excited state intramolecular proton transfer (ESIPT) mechanism is synthesized and employed for the selective recognition of aluminum(Al3+) ions and picric acid (PA) based on ‘off–on-off’ fluorescence mechanism. The sensor HID shows a turn-on fluorescence response towards Al3+ ions in 10 % (v/v) DMSO/H2O with a rapid response time (2 min) and exceptional sensitivity (LOD = 0.56 μM). The binding constant (K) of HID with Al3+ ions is estimated to be 1.32 × 108 M−2. The 1:2 stoichiometries of the complex between HID and Al3+ ions are confirmed through Job’s plot and 1H NMR spectral analysis. Al3+ chelated HID complex is further employed to detect explosive nitroaromatic compounds, especially PA. Furthermore, using these two chemically encoded inputs, viz. Al3+ and PA and corresponding optical output, we have constructed the INHIBIT molecular logic gate. The HID chemosensor and Al3+ chelated HID complex are also applied to map Al3+ ions and PA in the living cell. The HID chemosensor and Al3+ chelated HID complex's performance toward detecting Al3+ ions and PA demonstrates that they might be used as a signaling tool for the analysis of biological and environmental samples.

Tetraphenylethylene Based Fluorescent Chemosensor for the Selective Detection of Explosive Nitroaromatic Compounds

AbstractHerein, we have reported a tetraphenylethylene (TPE) based fluorescent chemosensor 4,4′,4′′,4′′′‐(ethene‐1,1,2,2‐tetrayl)tetrakis(N,N‐dimethylaniline) (TPE‐DMA) for the selective detection of explosive nitroaromatic compounds (NACs), such as 2, 4, 6‐trinitrophenol also called as picric acid (PA), 2,4‐dinitrophenol (DNP), and p‐nitrophenol (NP) over other NACs in CHCl3. TPE‐DMA is highly selective and sensitive toward PA in presence of various metal ions and anions. The quenching efficiency can be calculated from the Stern‐Volmer equation and was found to be 4.02×104 M−1, 1.82×104 M−1and 3.12×104 M−1 respectively for PA, DNP and NP. The detection limit of TPE‐DMA towards PA, DNP and NP of about 4.088×10−6 M, 5.155×10−6 M and 3.989×10−6 M respectively. Furthermore, to study the practical applicability of TPE‐DMA, visual‐eye detection was performed not only in solid‐state on TLC plates but also in solution state in CHCl3 under visible light as well as UV light illumination.

Selective Low-Level Detection of a Perilous Nitroaromatic Compound Using Tailor-Made Cd(II)-Based Coordination Polymers: Study of Photophysical Properties and Effect of Functional Groups.

Three coordination polymers (CPs 1-3) are prepared based on diverse electron-donating properties and coordination arrangements of conjugated ligands. Interestingly, this is also reflected in their photophysical properties. The distinguishable high emissive nature of the luminescent coordination polymer shows its potentiality toward the detection of the perilous substance 2,4,6-trinitrophenol (TNP) or picric acid (PA). TNP has a higher propensity among explosive nitroaromatic compounds (epNACs) due to its significant π···π interaction with the free benzene moieties present in the CPs. Among CPs 1-3, 2 exhibits the highest sensitivity and selectivity toward TNP because of the most favorable π-π stacking with the conjugated organic linker. The calculated limit of detection (LOD) and corresponding quenching constant (KSV) from the Stern-Volmer (SV) plot for 1, 2, and 3 are found to be 0.68 μM and 7.49 × 104 M-1, 0.41 μM and 8.01 × 104 M-1, and 1.18 μM and 8.1 × 104 M-1, respectively. The fluorescence quenching mechanism is also highly influenced by their structure and coordination arrangement.

2H-Pyran-2-one-Functionalized Diketopyrrolopyrrole Dye: Design, Synthesis, and Explosives Sensor.

In this work, a 2H-pyran-2-one-functionalized diketopyrrolopyrrole (DPP) (coded as receptor 1) was designed, synthesized, and fully characterized by various spectroscopic methods. The physical properties of molecular architecture 1 were studied employing theoretical calculations. Receptor 1 was elegantly scrutinized for the sensing of explosive nitroaromatic compounds (NACs). Receptor 1 exhibited detection of nitro explosives, i.e., picric acid (PA), 2,4-dinitrophenol (DNP), and nitrophenol (NP), via the fluorescence quenching mechanism. The Stern-Volmer equation was employed to evaluate the effectiveness of the quenching process. It was found that 1 exhibited a detection limit of about 7.58 × 10-5, 8.35 × 10-5, and 9.05 × 10-5 M toward PA, DNP, and NP, respectively. The influence of interfering metal ions and anions on PA detection was investigated thoroughly. Furthermore, receptor 1-based low-cost fluorescent thin-layer chromatography (TLC) plates were developed for the recognition of PA.

Crystal engineering of Pb(II)-salen coordination polymer enforced for the selective fluorescence NACs sensing activity in a dispersed aqueous medium: A combined experimental and theoretical DFT monologue

A new 1D coordination polymer (CP), [(SCN)Cd(L1)Pb(NCS)]n (1) was synthesized using N2O4-based Scaffold (H2L1 = N, N’-bis(3-methoxysalicylidenimino)-1,3-diaminopropane) and structurally characterized using various analytical instruments. X-ray structure disclosed complex (1) crystallize in the Orthorhombic space group P212121 with Z=4. The crystal structure contains heteronuclear units of [(SCN)Cd(L1)Pb(NCS)]n, linked by a μ1,1,3 thiocyanate (SCN−) bridging. Here weak S···S chalcogen, Pb···S tetrel bonding with two C-H···π(SCN) and one C-H···π(arene) like interactions are vividly observed. The QTAIM/NCI diagram successfully explains the nature of these contacts. Hirshfeld surface (HS) and 2D fingerprint plots analysis has described the non-covalent supramolecular features. The H…H interactions dominate the solid-state crystal structure. The complex fluorescence behaviour is eventually quenched in the presence of explosive nitroaromatic compounds. Complex (1) retained high fluorescence sensitivity and selectivity only for organo-toxin trinitrophenol (TNP). The Stern-Volmer equation evaluated the enhancement of the fluorescence mechanism, the limit of detection (LOD), and the quenching constant (KSV), which for TNP is 6.92 × 104 M−1. The turn-off fluorescence sensing mechanism is explained by (a) AIM/RDG surface interactions energy, (b) Charge-transfer complex, (b) Photo-induced electron transfer (PET) through the HOMO-LUMO approach, (c) Fluorescence resonance energy transfer (FRET), and (d) 1H NMR titration. Notably, the active dynamic sensing is due to a decrease in fluorescence lifetime after the successive addition of TNP with the polymer. Finally, the title complex (1) is employed as a quenched fluorescence response sensor for detecting TNP in a dispersed aqueous medium.

Target Analyte Interaction with a New Julolidine Coupled Benzoxazole‐based Dyad: A combined Photophysical, Theoretical (DFT), and Bioimaging Study

AbstractA julolidine‐coupled benzoxazole‐based fluorescent chemosensor (BPOZ) is designed and developed to investigate the different target analyte interactions spectroscopically. Based on the ′off‐on‐off′ photoluminescence mechanism, the as‐prepared BPOZ is used for sequentially detecting Zn2+ and HSO4− ions, respectively. The UV‐visible absorption and photoluminescence spectral behavior is intramolecular charge transfer (ICT) in nature. When Zn2+ ions bind with BPOZ, its fluorescence is significantly enhanced at 512 nm due to chelation‐enhanced fluorescence. A green color emission is also visible under 365 nm UV light exposure, which is also confirmed by the color chromaticity diagram. Chelation‐enhanced photoluminescence is also manifested in the lifetime decay analysis. Further, it is well supported by different spectroscopic techniques and DFT analysis. In the presence of HSO4− ions, photoluminescence of the Zn2+ chelated BPOZ complex is significantly reduced, rebirthing the free BPOZ. The detection limit of BPOZ for Zn2+ and Zn2+ chelated BPOZ complex towards detecting Zn2+ and HSO4− ions is established to be in the order of nM and μM range, respectively, in the solution phase. Among the various explosive nitroaromatic compounds, picric acid (PA) quenched the emission of the Zn2+ chelated BPOZ complex, and the quenching mechanism is found to be both static and dynamic in nature. Using these chemically prearranged inputs and optical outputs, two inputs, INHIBIT, and three inputs, combinational logic gates have been constructed. The BPOZ chemosensor and Zn2+ chelated BPOZ complex are also employed to map Zn2+ ions and PA in the living cell. The performance of the BPOZ chemosensor and Zn2+ chelated BPOZ complex toward Zn2+ ions and PA proved that it could be exploited as a signal tool for environmental and biological samples.

Single-Molecule Tunneling Sensors for Nitrobenzene Explosives.

The tunneling current through the single-molecule junctions principally offers the ultimate solution for chemical and biochemical sensing via the interactions between probes and target analytes at the single-molecule level. However, it remains unexplored to achieve the sensitive and selective detection of targeted analytes using single-molecule junction techniques due to the challenge in quantitative evaluation of sensing sensitivity and selectivity. Herein, we demonstrate a single-molecule tunneling sensor for the highly sensitive and selective detection of nitrobenzene explosives using scanning tunneling microscope break junction (STM-BJ). Taking advantage of π-π stacking interactions between the molecular probes and nitrobenzene explosives, we use a spectral clustering algorithm to assign the signal of probes and π-stacked probes for sensitively detecting the targeted analytes and the distinguishable conductance change of probes when interacting with different nitroaromatic explosive compounds for selective detection. We find that pronounced conductance changes up to 0.8 orders of magnitude when the probes interact with TNT. Also, we obtain a sensitivity of up to ∼10 pM for TNT and high sensitivity for eight TNT analogues. Combined with theoretical calculations, we discover that the harness of the destructive quantum interference of the probe M1OH after interacting with TNT leads to high selectivity in sensing with TNT. Our work demonstrates the great potential of the single-molecule tunneling current for environmental sensing molecules with high selectivity and sensitivity.

A coumarin coupled electron donor-acceptor dyad for cascade detection of aluminium ions and explosive nitroaromatic compounds

A coumarin coupled electron donor–acceptor dyad (HL) has been synthesized and characterized by different conventional techniques. Details spectroscopic investigation has been carried out to understand the photophysical behavior of as-prepared HL. The UV–visible spectral behavior of HL is found to be intramolecular charge transfer in nature and shows broadband, having maxima at 432 nm with a shoulder peak around 348 nm in DMF. The emission spectrum of HL also gives broadband, having maxima located at 480 nm in DMF. Further, HL is employed for the cascade detection of Al3+ ions (ON) and picric acid (PA, OFF) in DMF-H2O (7:3, v/v) media. A colorimetric change from yellow to colorless is observed in the presence of Al3+ ions. A significant fluorescence enhancement is observed due to the well coordination of Al3+ ions with HL. A visual bluish-green color could be seen under 365 nm UV light irradiation, which is also well supported by the color chromaticity diagram. The fluorescence of the HL-Al3+ complex is quenched in the presence of PA among all the tested nitroaromatic compounds. The sensitivity of HL and HL-Al3+ complex towards detection of Al3+ ions and PA can be possible down to 0.638 μM and 0.623 µM, respectively. The developed chemosensor is employed for the practical application for mapping Al3+ ions in the living cell. The performance of HL toward Al3+ ions proved that it could be exploited as a signal tool for environmental and biological samples.

Tetraphenylethylene Based Fluorescent Chemosensor for the Selective Detection of Explosive Nitroaromatic Compounds

Tetraphenylethylene Based Fluorescent Chemosensor for the Selective Detection of Explosive Nitroaromatic Compounds

Amino Appended Coumarin Composites for Pb2+Capturing in Aqueous Medium.

The C1-C3 receptors were synthesized by using coumarin and amines viz., 1-butylpiperazine (1), cis-myrtanylamine (2), and 3-methyldiphenyl amine (3) at room temperature without using harsh conditions. All the probes show beautiful and strong binding with Pb2+ ions among all the tested essential elements of human body. The binding is clearly seen and confirmed in UV-visible, NMR and HPLC studies. Also, all the substituted amines (1-3) are well known bioactives viz., piperazine as anthelmintic, cis-myrtanyl use for cannabinoid receptor (CB2) antagonists, 3-methyldiphenyl is used in probes for selective detection of explosive nitroaromatic compounds further increases their sensitivity for use as Pb2+ sensor. As they are already well in use for research on human body metabolomics their future introduction as sensors in the human body for lead toxicity is highly favourable.

Gas phase ion-molecule reactions of nitroaromatic explosive compounds studied by hollow cathode discharge ionization-mass spectrometry

In this study, we have developed a variable pressure operating hollow cathode discharge (HCD) ion source to investigate the gas phase ion-molecule reactions of nitroaromatic explosive compounds. The developed HCD ion source coupled MS system has also been validated as an analytical method to analyze explosives at trace levels. The ion source was designed in such a way that the plasma can be generated alternatively at high pressure (~30 Torr), medium pressure (~5 Torr) and low pressure (~1 Torr) regions. The plasma contains a sufficient amount of reactant ions, electrons and excited species, thus the gaseous analyte molecules were efficiently ionized when they passed through the plasma. In the ion-molecule reactions of the nitroaromatic explosives, the discharge products of NOx− (x = 2,3), O3 and HNO3 originating from the plasma-excited air were suggested to contribute to the formation of mostly [M − H]-, [M − NO]-, [M+NO3–HNO2]- and [M-NO+HNO3]- adduct ions at the higher ion source pressures (~5 and 28 Torr) while the electron rich plasma leads to the formation of molecular ion, M−•, at the lower ion source pressure (~1 Torr). Formation of the hydride-adduct ions of the nitroaromatic compounds reveals the surface-assisted Birch type reduction in the HCD plasma. The variety of spectral patterns in the air-assisted glow discharge would be useful for high through-put detection of TNT and TNT-related explosives. An ambient helium dielectric barrier discharge (DBD) ion source was also used and gave identical mass spectra of the nitroaromatic explosive compounds to those observed by the HCD ion source, but did not give any hydride-adduct ions of the explosive compounds. Ion formation mechanism of these ions is also discussed.