Detection Of Trinitrotoluene Research Articles

A highly sensitive and selective Zn-based luminescent MOF for specific detection of trinitrotoluene in aqueous phase

The existence of nitroaromatic compounds, specifically 2,4,6-trinitrotoluene (TNT), in water reservoirs poses significant health risks, necessitating robust detection and monitoring strategies. In this study, we leverage the exceptional properties of the previously synthesized metal-organic framework (MOF), PUC2 as a highly luminescent probe for selective and sensitive detection of TNT in aqueous media. PUC2 exhibits remarkable luminescence, emitting a vivid blue light, making it an ideal candidate for TNT detection. Our investigations reveal that PUC2 demonstrates outstanding sensitivity, achieving an impressive detection limit of 0.145 μM towards TNT which can be attributed to the robust probe-analyte interactions evident from the quenching constant (Ksv) value of 0.18 × 104M−1. An intriguing aspect of PUC2 is its adaptability to a wide pH range, maintaining its sensing capabilities effectively in aqueous phase with pH levels ranging from 4 to 11. The predominant quenching mechanism in this context appears to be photoinduced electron transfer (PET), with an additional enhancement through Forster resonance energy transfer (FRET). The unique combination of structural features and exceptional sensing capabilities of PUC2 opens up new avenues for environmental monitoring and security applications, highlighting its potential as a highly effective luminescent sensor for detecting hazardous substances like TNT.

A facile and novel AIE vesicle as nanoprobe for simple and rapid detection of TNT in water

Trinitrotoluene (TNT) in water will damage biological tissues and organs of the human body due to its high toxicity and risk. However, the simple and rapid detection of TNT in water is always a challenging task. Herein, we reported a novel aggregation-induced emission-a vesicle (AIE-a-V) as fluorescent nanoprobe for the detection of TNT in water by π-π self-assembly of π-π stacking induced aggregation-emission. The AIE-a-V was spherical in shape with a hydrodynamic diameter of ∼106 nm and possessed robust stability. In addition, the AIE-a-V showed strong fluorescence and its fluorescence would quickly disappear after contact with TNT. Based on this, without any cumbersome operation, the AIE-a-V could detect the presence of TNT in water within 60 s, and its minimum detectable concentration was as low as 50 nM. Moreover, the AIE-a-V could selectively detect TNT in water and would not be affected by other components, including other aromatic compounds, toxic metals, and acid-base. Therefore, the new AIE-a-V with simplicity, rapidity, sensitivity and selectivity have great application potential in the detection of TNT in water.

Selective aptasensor for trinitrotoluene detection: Comparison of the detecting performances from liquid and vapor phases

In general, chromatographic and sensor analyses have been utilized for explosive detection. The main interest on those systems is to develop a method to selectively detect explosives at a single step as well as from vapor phase if possible. Moreover, on-site and real-time detection with portable systems is another challenge for the researchers. On the other hand, the detection of 2,4,6-trinitrotoluene (TNT) vapor at the crime scene, preferably before the explosion is highly demanded in order to prevent the negative effects of terrorism and to ensure the safety of the civilian population. In this study, initially, Quartz Crystal Microbalance (QCM) sensor was prepared for real-time monitoring of TNT in aqueous solution, through the attachment of TNT peptide aptamer on the gold surface of QCM sensor. Secondly, after providing optimum conditions, TNT detection was investigated even from vapor phase through the QCM aptasensor. According to results, the selectivity coefficient of QCM-based aptasensor was calculated as 6.78 for TNT in respect to DNT whereas that was calculated as 9.02 for TNT in respect to TNB. In addition, the evaluation of the reusability and storage stability emphasized that the sensor could be used repeatedly without significant reduction in dissipation (∆D) values. The linearity coefficient (R2) was found to be 0.9965. The limit of detection (LOD) and the limit of quantitation (LOQ) were determined as 0.0238 and 0.0739 nM, respectively. The studies demonstrated that the portable QCM sensor decorated with the aptamer selective for TNT molecules could be classified as a promising alternative, selective, cost-friendly, easy-to-prepare, ready-to-use, and applicable for on-site and real-time explosive measurements (even from vapor phase).

New fluorescent reporters capable of Ultra-sensitively detecting trinitrotoluene on surfaces: A proof-of-concept for finding hidden nitroaromatics in the workroom

We describe the proof of concept of a portable testing setup for the detection of trinitrotoluene (TNT), a common component in hidden explosive devices. The system allows for field-testing and generation of real-time results to test for TNT traces in surfaces by simply using a filter paper and a fluorescent reporter. In this way, the controlled trapping and detection of the analyte by a chemical sensor gives reliable results at extremely low concentrations of TNT on surfaces under real life conditions suitable for daily use in ordinary sampling for example at airlines luggage storage or sport locker rooms. The reported fluorescent methodology is very sensitive and selective, allowing for the trapping and detection of TNT by a fluorescent reporter to give reliable results at very low concentrations. As a complement, we report the preparation of a modified Sylgard film that is useful under real conditions for qualitative fluorescent detection of hidden traces of TNT on surfaces or fingers by a swab method. The combination of quantitative and qualitative detection of TNT traces on surfaces constitutes a comprehensive new method for the detection of hidden nitroaromatic explosives in the workplace.

Synthesis and crystal structure of the 6-oxyquinoline derivative cyclotriphosphazene chemosensor with high selectivity and immediate sensitivity for Fe(III) ion and TNT detection

New flexible hexapodal cyclotriphosphazene molecule, named 2,2,4,4,6,6-hexakis(quinoline-6-yloxy)cyclotriphosphazene (QCP) was designed and synthesized. The isolated compound was characterized by elemental analysis, NMR (proton decoupled 31P{H}, 1H, 13C, and COSY 1H) and FT-IR spectroscopy, mass analysis and single crystal X-ray crystallography. X-ray crystal structure analysis revealed that QCP crystallize in monoclinic crystal system with P2/c space group. According to TGA analysis, compound exhibited high thermal stability up to ∼ 355 °C. The photophysical and chemosensor properties of the QCP against a series of analytes (various metal ions and nitro compounds) were investigated by UV–Vis and Fluorescence spectrophotometer. A significant increase in UV–Vis absorption signals were observed with the addition of Fe(III) ions and TNT(trinitrotoluene), and the detection limits for these analytes were calculated as 1.40 and 0.42 μM, respectively. In addition, the complex stoichiometry of QCP and selective analytes was determined as 1:2 (L/M) by UV–Vis absorption titrations (Job's plot). This study showed that the donor N atoms on the QCP interact selectively with Fe(III) ion. It also showed that the oxyquinoline rings in QCP interact with the TNT ring through intermolecular π-π and CH-π stacking interactions.

Plasmonic Coupling of Au Nanoclusters on a Flexible MXene/Graphene Oxide Fiber for Ultrasensitive SERS Sensing.

High sensitivity, good signal repeatability, and facile fabrication of flexible surface enhanced Raman scattering (SERS) substrates are common pursuits of researchers for the detection of probe molecules in a complex environment. However, fragile adhesion between the noble-metal nanoparticles and substrate material, low selectivity, and complex fabrication process on a large scale limit SERS technology for wide-ranging applications. Herein, we propose a scalable and cost-effective strategy to a fabricate sensitive and mechanically stable flexible Ti3C2Tx MXene@graphene oxide/Au nanoclusters (MG/AuNCs) fiber SERS substrate from wet spinning and subsequent in situ reduction processes. The use of MG fiber provides good flexibility (114 MPa) and charge transfer enhancement (chemical mechanism, CM) for a SERS sensor and allows further in situ growth of AuNCs on its surface to build highly sensitive hot spots (electromagnetic mechanism, EM), promoting the durability and SERS performance of the substrate in complex environments. Therefore, the formed flexible MG/AuNCs-1 fiber exhibits a low detection limit of 1 × 10-11 M with a 2.01 × 109 enhancement factor (EFexp), signal repeatability (RSD = 9.80%), and time retention (remains 75% after 90 days of storage) for R6G molecules. Furthermore, the l-cysteine-modified MG/AuNCs-1 fiber realized the trace and selective detection of trinitrotoluene (TNT) molecules (0.1 μM) via Meisenheimer complex formation, even by sampling the TNT molecules at a fingerprint or sample bag. These findings fill the gap in the large-scale fabrication of high-performance 2D materials/precious-metal particle composite SERS substrates, with the expectation of pushing flexible SERS sensors toward wider applications.

A novel pyrenyl-furan hydrazone on paper-based device for the selective detection of trinitrotoluene

T2 paper-based sensor detection of TNT was linear from 30–500 μM with a detection limit of 30 μM. The T2 paper-based sensor can detect TNT with high selectivity and sensitivity.

Gold nanoclusters-engineered dual-emitting nanofibrous film for fluorescent discrimination and visual sensing of explosives

Development of reliable sensors for explosive detection is important to reduce explosion-related safety risks and mitigate widespread environmental concerns. However, it remains highly challenging to achieve on-site detection of multiple analytes in a simple yet efficient way. Herein, a flexible electrospun film-based sensing platform by engineering with dual-emitting gold nanoclusters (AuNCs) has been fabricated for the simultaneous fluorescent detection of two representative explosives, hexanitrohexaazaisowurtzitane (CL-20) and trinitrotoluene (TNT). Particularly, two types of AuNCs with different emission colors (green and red) and surface chemistry are designed, which can specifically respond to trace amounts of two explosives separately. While the presence of CL-20 can remarkably enhance the green emission of l-arginine/6-aza-2-thiothymine-protected AuNCs, the presence of TNT can efficiently quench the red emission of glutathione-protected AuNCs. Consequently, ratiometric fluorescent sensing of CL-20 and TNT can be achieved with these dual-emitting AuNCs (G/R-AuNCs), which exhibits a detection limit down to 0.55 and 2.38 µM, respectively. The distinct “turn on” and “turn off” response patterns of G/R-AuNCs towards two explosives could be harnessed to construct fluorescent “BUF” and “NOT” logic gates. Moreover, the present AuNCs-based explosive sensors were deposited into flexible electrospun nanofibrous film for visual and quantitative detection of CL-20 and TNT, which exhibit good mechanical property and promising sensing performance. This work provides a new approach to design explosive sensing platform by coupling the attractive features of fluorescent AuNCs to the electrospun nanofibrous film, which holds great potential for further practical applications.

Cluster of Hexamolybdenum [Mo6Cl14]2- for Sensing Nitroaromatic Compounds.

This contribution describes a novel method for the detection of trace amounts of trinitrotoluene (TNT) using a cluster of hexamolybdenum with general formula [Mo6Cl14]2–. The molybdenum cluster was characterized by UV–visible, FT-IR, and fluorescence techniques, and the synthesis was efficient and reproducible. The evaluation of the molybdenum cluster by TNT detection was perfomed by fluoresecent measurements, and the results were interpreted by the Stern–Volmer equation, obtaining KSV values of 2.9 × 105 and 1.6 × 104 M–1 in different concentration ranges. Further, the results suggest that at TNT concentrations higher than 4 × 10–5 mM (0.01 mg L–1) it is possible to measure the quenching of the cluster fluorescence. The DFT calculations indicate that the contribution of the TNT in the active lowest unoccupied molecular orbitals that are involved in the higher intensity transitions in the complex cluster–TNT are significant. This situation differs from all the luminescent [M6X8L6]2– clusters (M = Mo; X = facial bridging ligand, and L = labile axial ligands), where most of the closely spaced excited states are located in the {M6X8}q+ core. Thus, the TNT switches off the cluster luminescence. The approach using a [Mo6Cl14]2–-based fluorescence sensor has the potential to be a sensing technology for the detection of nitroaromatic explosives.

Computational design of a nanoconjugate model of pyrene-linked CdTe quantum dot for the detection of trinitrotoluene

This paper demonstrates a computational design of the CdTe QD-based nanoconjugate to detect trinitrotoluene (TNT). The bandgap of QD-pyrene nanoconjugate has been engineered depending on the nitrotoluenes attached. The bandgap is reduced significantly for TNT in comparison to others because the LUMO of TNT appeared at the mid-gap region of CdTe QD. The QD guides the VBT, and the lowest conduction band is the LUMO of TNT; hence CdTe QD-pyrene/TNT constructs a type-II band alignment. The dinitrotoluenes (DNTs) also construct the type-II band alignment. However, toluene and mononitrotoluenes (NTs) do not alter the bandgap of larger CdTe QD and construct the type-I band alignment. Significant reduction of the bandgap along with type-II band alignment may facilitate the photoexcited electron transfer from QD to TNT. One can expect rapid fluorescence quenching of CdTe QDs by TNT. So, the designed pyrene-linked CdTe QD-based nanoconjugate can act as an effective TNT sensor.

High sensitivity and fast detection system for sensing of explosives and hazardous materials

We demonstrate a high sensitivity and fast detection system for sensing of explosives and hazardous materials based on the external cavity quantum cascade laser (ECQCL). In this system, one galvanometer is utilized as the tuning component of the ECQCL to get high wavelength scanning speed. Meanwhile, the driving module of the galvanometer and the analog to digital conversion (ADC) module for data acquisition are synchronized, which brings in great significance for fast high sensitivity detection. For one thing, this synchronization exactly defines the data of each scanning period during data acquirement and processing, which enables our system to avoid data dislocation and cumulative error. For another, enough averaging times are allowed to obtain high sensitivity while detection speed is high enough for practical application. To verify the practical application effect, this system was utilized to detect trace amount of adsorbed trinitrotoluene (TNT) on the People's Republic of China Resident Identity (ID) Card. Although the wavelength tuning rate was as high as 17400 cm−1/s over the range of 1280–1454 cm−1(∼6.88–7.81 µm) with scanning frequency of 100 Hz, a TNT detection sensitivity of 1 μg/cm2 was achieved with detection speed of one result per second through multiple averaging technique.

Benzimidazolium ionic liquid tagged phenazine salophen as a bifunctional ‘off–on’ PET based fluorescent sensor for aqueous phase detection of trinitrotoluene and picric acid

Water soluble IL tagged phenazine salophen was synthesized and utilized as a fluorescent probe for discriminative detection of TNT and picric acid, which exhibits FL enhancement with TNT due to restriction of PET and FL quenching with PA due to PET.

TNT Sensor: Stern–Volmer Analysis of Luminescence Quenching of Ruthenium Bipyridine

TNT is both toxic and explosive, and therefore, the detection of TNT represents an environmental concern and a security concern. Dogs are often used for detection, but other methods are needed. This laboratory investigates a ruthenium bipyridine ([Ru(bpy)3]2+) luminescence-based trinitrotoluene (TNT) sensor. Students will synthesize [Ru(bpy)3]2+, investigate sensors, and consider possible mechanistic pathways of quenching. Students are unlikely to have analyzed luminescence quenching data previously, and using TNT shows how important the technique is for problems like national security, environmental contamination, and land mine deactivation. The content of the lab is ideal for upper-level laboratories, when students have the foundational coursework to appreciate the interdisciplinary nature of chemistry as the experiment integrates inorganic, analytical, and physical chemistry.

A Novel Strategy for Trinitrotoluene Detection Using Functionalized Gold Nanoparticles

Gold nanoparticles (AuNPs) with unique optical properties, such as easy operation and visualized assay, have a great ability to detect different types of analytes. In the present study, a novel AuNPs based aptasensor strategy for the detection of trinitrotoluene (TNT) was used. For this purpose, two different batches of AuNPs were functionalized by thiol modified DNA probes (P1 and P2) complementary to 5' and 3' ends of anti-TNT aptamer. Then, two batches of gold nanoprobes were mixed and the addition of anti-TNT aptamer induced the assembly and aggregation of nanoparticles. However, according to this strategy, in the presence of TNT, aptamer can bind to its target molecule (TNT) and prevent nanoparticles aggregation. The results indicate that the produced aptasensor can detect TNT molecule with high specificity (detection limit of 6 pM). In conclusion, this gold nanoparticle-based colorimetric anti-TNT aptasensor can be used in the next investigations with high efficiency.

Improved selectivity for the determination of trinitrotoluene through reactive stage tandem ion mobility spectrometry and a quantitative measure of source-based suppression of ionization

A tandem ion mobility spectrometer was used to mobility isolate ions at the drift time for trinitrotoluene (TNT) in a first mobility stage, remove an interfering compound by ion decomposition in a middle reactive stage, and mobility characterize the remaining TNT ions in a second mobility stage. This sequential processing of ions provided decisive detection of TNT in the presence of an interfering peak differing from TNT in reduced mobility coefficient (Ko) by only 0.02 cm2/V. Even though ions of TNT (as M − 1)- and the interfering compound were more than 90% convolved, TNT could be selectively detected with more than 95% decomposition of the interferent at 123 Td to an ion now separated by ΔKo of 0.2 cm2/V from TNT. Ions for TNT were not decomposed in these electric fields though transmission efficiency was decreased by 20% through a wire grid assembly (the reactive stage). Although tandem ion mobility spectrometry with a reactive stage improves selectivity of measurement in the drift time dimension, the chemistry of ion formation in the ion source is affected still by ion suppression. Response to 1 ng TNT was decreased as much as 30% from 200 ng of interferent deposited on sample trap.

GNPs-QDs core–satellites assembly: trimodal platform for on-site identification and detection of TNT in complex media

Accurate, sensitive, and selective on-site screening of explosives are of crucial importance in antiterrorism and homeland security. Here, we proposed a first tri-mode method capable of on-site discrimination and detection of trinitrotoluene (TNT) by utilizing the colorimetric, fluorescence and surface-enhanced Raman scattering (SERS) response of Au nanoparticles (GNPs)@quantum dots (GNPs-QDs) core-satellite assemblies. The cysteamine-modified GNPs and mercaptopropionic acid-capped CdTe QDs directly assemble each other due to electrostatic interaction, leading to significant photoluminescence quenching because of a high-effective (>95%) energy transfer from QDs to GNPs. However, the addition of TNT into GNPs-QDs assemblies induces formation of Meisenheimer complex (cysteamine-TNT complex) and destroys core-satellite structures, causing increment in colorimetric and fluorescent signals of hybrid system, which facilitates visualization of TNT by the naked-eyes. Importantly, the superior affinity of TNT toward cysteamine triggers self-aggregation of GNPs and enhancement of Raman signals of TNT, allowing for distinguishing of TNT from its analogues. The GNPs-QDs based trimodal strategy exhibits good linearity between 10 fM and 200 μM with a detection limit of 3.2 fM. Moreover, the proposed sensing system validates a reliable quantitative analysis of TNT from environmental specimens including soil, clothing, fruit, and liquor in a portable and rapid feature. The excellent performance makes the sensing platform ideal for point-of-care applications in forensic arena and homeland defense.

Nitrogen-doped carbon quantum dots conjugated isoreticular metal-organic framework-3 particles based luminescent probe for selective sensing of trinitrotoluene explosive.

Amine group-containing isoreticular metal-organic framework (IRMOF-3) particles are utilized for the first time as a trinitrotoluene (TNT) sensing material. IRMOF-3 particles are synthesized using zinc nitrate as a metal precursor and 2-amino-1,4-benzenedicarboxylic acid as a linker. The nitrogen-doped carbon quantum dots (NCQDs) are synthesized from citric acid and ethylenediamine as carbon and nitrogen precursor, respectively. The NCQDs are conjugated with IRMOF-3 particles as IRMOF-3/NCQDs. The TEM micrograph revealed the average size of IRMOF-3 particles to be 363.66nm. The photoluminescence emission intensity of IRMOF-3 particles at λem 430nm is highly increased in the presence of NCQDs (λex 330nm). Both the as-synthesized IRMOF-3 and IRMOF-3/NCQD particles are explored for TNT detection to compare the effect of NCQDs on the IRMOF-3 particle surface. Lower limit of detection (7.5 × 10-8M) and higher Stern-Volmer constant (4.46 × 106M-1) are achieved by IRMOF-3/NCQD particles. The association constant also increased from 5.3 × 104 to 2.78 × 106M-1 after the conjugation of IRMOF-3 particles with NCQDs. Moreover, enhanced selectivity for TNT over trinitrophenol is achieved using the IRMOF-3/NCQD particles. Graphical Abstract.

Tetramethylammonium Hydroxide-doped Starch Film as a Colorimetric Sensor for Trinitrotoluene Detection.

A tetramethylammonium hydroxide (TMAH)-doped starch film was developed for trinitrotoluene (TNT) detection. A purple Janowsky anion was obtained from the reaction of TNT with released TMAH. When the film was used in conjunction with digital image colorimetry (DIC), rapid quantitative analysis of TNT was achieved. The Red-Green-Blue (RGB) intensities analyzed from digital photographs of the purple product were used to establish calibration curves for TNT. A wide linear range (2.5 to 50 mgL-1) with good linearity (R2 > 0.99) was achieved for the quantification of TNT. Good precision (1.73 to 3.74%RSD) was obtained for inter-day tests (n = 5). The films were applied to test four post-blast soil samples and two positive results were observed. The concentrations quantified by DIC were in good agreement with spectrophotometry. The film was able to be stored in a freezer for 3 months with <4.3% change in performance.

Tb-doped BSA-gold nanoclusters as a bimodal probe for the selective detection of TNT.

Trinitrotoluene (TNT) is a widely used explosive belonging to the family of nitroaromatic compounds, and its misuse poses a significant threat to society. Herein, we propose a Tb-BSA-AuNC fluorescent and colorimetric sensing probe for the selective onsite detection of TNT in the aqueous phase. Tb-doped BSA-protected gold nanoclusters (Tb-BSA-AuNCs) were synthesized by a microwave-assisted method, and TNT detection was carried out utilizing the chemistry of Meisenheimer complex formation. Tb doping of gold nanoclusters was demonstrated to facilitate better electron shuttling effects and thereby improve the efficiency of complex formation between the TNT and gold nanoclusters. A paper strip assay was also developed for TNT detection with the designed probe. Limits of detection and quantification of 0.2136mM and 0.7120mM, respectively, were achieved. Graphical abstract.

Tfbar Sensors for Detection of Explosives Substances

Tfbar Sensors for Detection of Explosives Substances