Determination Of TNT Research Articles

Sensitive and selective impedimetric determination of TNT using RSM-CCD optimization

Detection of trace amounts of 2,4,6-Trinitrotoluene as a widely used explosive in the military and industrial sectors is of vital importance due to security and environmental concerns. The sensitive and selective measurement characteristics of the compound still is considered a challenge for analytical chemists. Unlike conventional optical and electrochemical methods, the electrochemical impedance spectroscopy technique (EIS), has a very high sensitivity, but it faces a significant challenge in that it requires complex and expensive steps to modify the electrode surface with selective agents. We reported the design and construction of an inexpensive, simple, sensitive, and selective impedimetric electrochemical TNT sensor based on the formation of a Meisenheimer complex between magnetic multiwalled carbon nanotubes modified with aminopropyl triethoxysilane (MMWCNTs @ APTES) and TNT. The formation of the mentioned charge transfer complex at the electrode-solution interface blocks the electrode surface and disrupts the charge transfer in [(Fe (CN) 6)] 3−/4- redox probe system. Charge transfer resistance changes (ΔRCT) were used as an analytical response that corresponded to TNT concentration. To investigate the influence of effective parameters on the electrode response, such as pH, contact time, and modifier percentage, the response surface methodology based on central composite design (RSM-CCD) was used. The calibration curve was achieved in the range of 1–500 nM with a detection limit of 0.15 nM under optimal conditions, which included pH of 8.29, contact time of 479 s, and modifier percentage of 12.38% (w/w). The selectivity of the constructed electrode towards several nitroaromatic species was investigated, and no significant interference was found. Finally, the proposed sensor was able to successfully measure TNT in various water samples with satisfactory recovery percentages.

Chemical reduction as a facile colorimetric approach for selective TNT detection by spectrophotometry and photothermal lens spectroscopy

In this study, the simple determination of TNT is achieved through the vivid stable red color products generated after chemically reduction by NaBH4 as a common and accessible reducing/colorimetric reagent. Some other nitroaromatics were impressed under reduction reaction and led to the colorful products. The color of these reduced nitroaromatics were unstable and approximately vanished after some few minutes which ameliorated the selectivity in TNT determination. Utilizing the time-dependent selectivity, the method was applied specifically for discriminating of TNT from other nitroaromatic compounds (NACs). UV–vis spectrophotometry and photothermal lens spectrometry were employed as detection techniques. The former was simpler and more available in various laboratories while the latter provides higher sensitivity. It was revealed that the photothermal lens responses were linear from 2.0 to 55.0 nM with a limit of detection (LOD) of about 0.8 nM. The LOD of the photothermal lens measurement were found to be 241 times lower than that of the UV–vis spectrophotometry in TNT quantification. The evolved method was successfully carried out for TNT vapor determination after trapping into the colorimetric reagent. The recoveries and relative standard deviations (RSD, n = 3) calculated for 3 gas samples were ≥91% and ≤7%, respectively.

Electrochemical Determination of 2,4,6-Trinitrotoluene by Linear Sweep Voltammetry Using a Gold Nanoparticle/Mesoporous Graphitic Carbon Nitride Modified Glassy Carbon Electrode

A novel electrochemical sensor for 2,4,6-trinitrotoluene (TNT) was constructed using a glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs)/mesoporous graphitic carbon nitride(mpg-C3N4) nanocomposite (hereafter designated by AuNPs/mpg-C3N4). A facile method based on ultraviolet excitation was used to produce the AuNPs/mpg-C3N4 nanocomposite. The new AuNPs/mpg-C3N4 nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy. The AuNPs were evenly distributed on the surface of mpg-C3N4. The AuNPs/mpg-C3N4 modified GCE sensor shows high sensitivity (viz., 0.32 μA/μM) and a low TNT detection limit (42 ppb) by linear sweep voltammetry (LSV). The enhanced electrochemical performance of AuNPs/mpg-C3N4 GCE is attributed to synergistic interactions between AuNPs and mpg-C3N4. The AuNPs/mpg-C3N4/GCE demonstrated good selectivity, stability, and reproducibility for TNT. The AuNPs/mpg-C3N4/GCE show a 100% ± 5% TNT recovery for natural water analysis. The results show the potential in AuNPs/mpg-C3N4/GCE sensor applications for the determination of TNT.

A sensitive colorimetric nanoprobe based on gold nanoparticles functionalized with thiram fungicide for determination of TNT and tetryl

Water and soil pollution (especially by explosive residues) is a global environmental problem, and tackling with this problem involves the selective and sensitive development of analytical techniques for trace explosives detection. In this regard, a gold nanoparticles (AuNPs)-based colorimetric probe was developed for the determination of TNT and tetryl as nitro-explosives. Au-nanoparticles were synthesized and their surface was modified with a fungicide, tetramethylthiuram disulfide (thiram), having both Au-anchoring S-atoms and TNT/tetryl ligating tert-amine groups as charge donors. The prepared probe (AuNPs@Thr) rapidly aggregated as a result of donor–acceptor (D-A) interaction between the amine group of thiram and the nitro-groups of explosives (TNT and tetryl), resulting in a bathochromic shift in the characteristic surface plasmon resonance band of AuNPs@Thr. Detection and quantification limits (LOD and LOQ) for TNT and tetryl were found as 5 and 15 ppb (µg L-1), respectively. Common soil ions (Cd2+, Fe3+, Fe2+, Mn2+, Zn2+, Mg2+, Cu2+, Al3+, Co3+, Ca2+, K+, Na+, Cl-, NO3–, SO42-, NO2–, and CO32–) did not interfere, and the explosive mixtures (comp B, synthetic comp B, and tetrytol) having TNT and tetryl constituents could be effectively analyzed with the proposed method. The method was validated against the reference LC–MS/MS method, applied to sandy soil samples contaminated with TNT and tetryl. Thiram as AuNPs − modifier was much cheaper than other aminothiols for probe manufacture, but could compete with them with respect to selectivity and sensitivity of nitro-explosives assay.

Small molecule based water-soluble fluorescence material for highly selective and ultra-sensitive detection of TNT: Design and spectrofluorimetric determination in real samples

A novel water-soluble double-anthracene bridged material consisting of two cyclotriphosphazene cores (5) as a small molecule was designed and systematically synthesized. The developed small molecule was used for ultra-sensitive and highly selective spectrofluorimetric determination of TNT in 100 % aqueous media. The characterization of 5 was examined by standard spectroscopic techniques. Fluorescent sensor features of 5 towards TNT were examined by UV–vis absorption, steady-state-, time-resolved-, and 3D-fluorescence measurements. The interaction and fluorescence mechanisms were investigated by DFT. The designed fluorescent sensor demonstrated a “turn-off” response towards TNT and required measurement conditions were evaluated for the determination of TNT in environmental waters. The LOD and LOQ for TNT were found as 0.030 and 0.091 mg.L−1 in the linear response of 0.02−15.00 mg.L−1 (R2 = 0.9964), respectively. This study demonstrated that 5 selectively interacted with TNT via intermolecular π-π and CH-π stacking interactions which led to effective electron transfer resulting in a “turn-off” response. The spectrofluorimetric determination of TNT in environmental waters was performed under optimized conditions and the accuracy was evaluated with HPLC and spike/recovery test. In addition, paper-based test kits were prepared for the detection of TNT, which can be easily used for highly selective, portable, sensitive, and rapid field analysis.

Photothermal lens microfluidic sensor for femtomole detection of 2,4,6-trinitrotoluene based on Meisenheimer complexation

Since the simple and accurate quantification of 2,4,6-trinitrotoluene (TNT) traces is still a challenge for analytical chemists, we employed a recently developed crossed-beam photothermal lens spectrometer for highly sensitive and selective determination of TNT through a well-known Meisenheimer complexation with n-butylamine (nBA). The colorless solution of TNT in dimethyl sulfoxide (DMSO) was changed to deep-red after the addition of nBA. Hence, we used a 532 nm diode laser as excitation source in photothermal lens investigations. All the instrumental parameters and chemical conditions such as chopper frequency, sample flow velocity, amine concentration and etc. were optimized. Photothermal lens measurements yielded a linear signal dependence on TNT quantity from 5 to 100 nM. The limit of detection (LOD) was 1.6 nM (˜5 fmol). The method was successfully carried out for determination of the TNT vapor extracted into the 300 μL dimethyl sulfoxide (DMSO).

Hybrid Optoelectrochemical Sensor for Superselective Detection of 2,4,6-Trinitrotoluene Based on Electrochemical Reduced Meisenheimer Complex

2,4,6-Trinitrotoluene (TNT) is known as one of the most used explosives, and its detection is significant in public security, human health, and environmental protection. The fabrication of absorbance based optical sensors for TNT is a serious challenge due to poor selectivity and sensitivity. We reported the design and fabrication of a superselective hybrid optoelectrochemical sensor based on the electrochemical reduction of Meisenheimer complex in a deep eutectic solvent (DES) modified with n-butylamine (nBA) for determination of TNT. The hybrid optoelectrochemical sensor (HOPES) that placed in DES modified with nBA and also an optical sensor (OPS) were fabricated. The electrochemical reduction of Meisenheimer complex occurred at HOPES when the potential was applied and consequently the sensing performance (sensitivity and selectivity) was dramatically enhanced compared to OPS. The both OPS and HOPES responded linearly to TNT with detection limits of 310 and 8 nmol L-1, respectively. The selectivity observed for the HOPES toward TNT compared to the other interferences was enhanced by a factor of 103-104, thus we can use the term "superselectivity" for HOPES. The mechanism of HOPES response was proved by optoelectrochemical and electrochemical impedance spectroscopy (EIS) techniques. The field emission scanning electron microscope (FESEM) was employed for the characterization of electrodeposited Meisenheimer layer. Finally, we presented a proposed model for the sensing mechanism of OPS and HOPES based on TNT complexation in the absence and presence of electric potential, respectively.

Electrochemical Determination of TNT, DNT, RDX, and HMX with Gold Nanoparticles/Poly(Carbazole-Aniline) Film-Modified Glassy Carbon Sensor Electrodes Imprinted for Molecular Recognition of Nitroaromatics and Nitramines.

Since nitroaromatic- and nitramine-type energetic materials, mostly arising from military activities, are persistent pollutants in soil and groundwater, on-site sensing of these hazardous chemicals has gained importance. A novel electrochemical sensor was designed for detecting nitroaromatic- and nitramine-type energetic materials, relying on gold nanoparticles (Aunano), modified glassy carbon (GC) electrode coated with nitro-energetic memory-poly(carbazole-aniline) copolymer (Cz- co-ANI) film (e.g., TNT memory-GC/P(Cz- co-ANI)-Aunano modified electrode). Current was recorded against concentration to build the calibration curves that were found to be linear within the range of 100-1000 μg L-1 for 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT): 50-1000 μg L-1 for 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The corresponding limits of detection were 25 μg L-1 for TNT, 30 μg L-1 for DNT, and 10 μg L-1 for both RDX and HMX, using nitro-energetic memory-GC/P(Cz- co-ANI)-Aunano electrodes. These electrodes were used separately, and specific determinations were made in various mixtures of nitro-energetic materials. The developed method could be efficiently used in electroanalyzing nitroaromatics and nitramines in military explosives (i.e., comp B, octol, and comp A5). The sensor electrodes were specific for the tested nitro-energetic compounds and did not respond to paracetamol-caffeine-based analgesic drug, acetylsalicylic acid (aspirin), sweetener, and sugar that can be used as camouflage materials in passenger belongings. The developed method was statistically validated against the standard LC-MS reference method in contaminated clay soil samples containing TNT and RDX explosives.

Chemiresistor gas sensor based on sulfonated dye-doped modified conducting polypyrrole film for high sensitive detection of 2,4,6-trinitrotoluene in air

2,4,6-Trinitrotoluene (TNT) is a widely used nitroaromatic explosive and its detection is important in the public security, environmental protection and human health. We presented a sensitive chemiresistor gas sensor based on modified nanostructured dye-doped polypyrrole (PPy) as anfilm to detection of TNT for the first time. The chemiresistor gas sensors were fabricated via electrosynthesis of PPy on Au interdigital electrodes (Au-IDEs) in the presence of the sulfonated dyes. The films were modified with n-butylamine (nBA), and they could absorb TNT molecules by the formation of the Meisenheimer complex. The role of the sulfonated dyes on the behavior of films was studied. The properties of the polymeric films before and after modification were investigated by scanning electron microscopy, elemental mapping analysisand spectroelectrochemical methods The mechanism of sensing was studied by spectroelectrochemical method and response of modified gas sensor was compared to unmodified sensor. The spectroelectrochemical measurements showed that the potential-dependent of spectra in PPy-Dye films is more than in PPy-ClO4 film after modification. Thus dye molecule can act as versatile compound in the polymer backbone. It was found that modified chemiresistor gas sensor has a high sensitivity and good selectivity to TNT over other related gases and no response without modification. The detection limit and linear dynamic range for determination of TNT was 0.2ppb and 9.7–827.8 ppb, respectively.

Ratiometric fluorescence “Turn On” probe for fast and selective detection of TNT in solution, solid and vapour

Fluorescent probe UREA-TP undergoes nearly 600% increase in emission intensity at 310nm on addition of 1 equivalent of TNT, but the emission band centered at 440nm remains unchanged. UREA-TP acts as a ratiometric fluorescence “turn-on” probe and can detect TNT between 10−9 to 10−5M with limit of detection as low as 100 pM. Paper strips coated with UREA-TP on interaction with TNT become fluorescent purple under 365nm light and can determine both qualitatively and quantitatively as low as 10μl solution of 10−13M TNT, which accounts for 2.27×10−16gcm−2 TNT, significantly lower than the TNT concentration allowed in drinking water by EPA. The common nitroaromatic derivatives 2,4-DNT, 2,6-DNT, picric acid and 2,4-DNP, the pain killers, food supplements and inorganic anions show insignificant interference in the determination of TNT using UREA-TP. The aggregate size determination using dynamic light scattering analysis and morphological studies using TEM investigations reveals that UREA-TP in H2O-DMSO (98:2) remains in aggregate state with average size of 200nm, which undergo further aggregation to larger size aggregates with increasing amounts of TNT.

Selective chemiluminescence method for the determination of trinitrotoluene based on molecularly imprinted polymer-capped ZnO quantum dots

A novel molecularly imprinted polymer (MIP) based chemiluminescence (CL) assay is described for the determination of TNT in environmental samples.

Mesoporous structured MIPs@CDs fluorescence sensor for highly sensitive detection of TNT

A facile strategy was developed to prepare mesoporous structured molecularly imprinted polymers capped carbon dots (M-MIPs@CDs) fluorescence sensor for highly sensitive and selective determination of TNT. The strategy using amino-CDs directly as “functional monomer” for imprinting simplify the imprinting process and provide well recognition sites accessibility. The as-prepared M-MIPs@CDs sensor, using periodic mesoporous silica as imprinting matrix, and amino-CDs directly as “functional monomer”, exhibited excellent selectivity and sensitivity toward TNT with detection limit of 17nM. The recycling process was sustainable for 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of TNT in soil and water samples with satisfactory recoveries of 88.6–95.7%. The method proposed in this work was proved to be a convenient and practical way to prepare high sensitive and selective fluorescence MIPs@CDs sensors.

Graphene Nanoribbon-Supported PtPd Concave Nanocubes for Electrochemical Detection of TNT with High Sensitivity and Selectivity.

In this work, PtPd concave nanocubes anchored on graphene nanoribbons (PtPd-rGONRs) were successfully fabricated through a hydrothermal process. The structural characterizations confirmed that PtPd concave cubes with an average size of around 11 nm have been successfully synthesized and they are uniformly assembled on the surface of rGONRs. The electrochemical measurements demonstrated that the PtPd-rGONRs composite-modified glassy carbon electrode (GCE) shows much enhanced current signals for TNT reduction, which is 4 and 12-fold higher than rGONRs and bare glassy carbon electrode, respectively. The PtPd-rGONRs exhibited a wide linear range for TNT detection from 0.01 to 3 ppm with the sensing limit of 0.8 ppb. Moreover, the PtPd-rGONRs showed excellent detection stability for the determination of TNT. Most importantly, the PtPd-rGONRs-based electrochemical detection platform can be successfully applied to TNT detection in tap water and real lake water samples. The present study indicates that graphene nanoribbon-supported nanocrystals are promising in designing high performance electrochemical sensors for explosives detection.

Label-Free Electrochemiluminescence Aptasensor for 2,4,6-Trinitrotoluene Based on Bilayer Structure of Luminescence Functionalized Graphene Hybrids.

The electrochemiluminescence (ECL) behavior of N-(aminobutyl)-N-(ethylisoluminol)/hemin dual-functionalized graphene hybrids (A-H-GNs) and luminol-functionalized silver/graphene oxide composite (luminol-AgNPs-GO) was investigated under cyclic voltammetry and pulse potential. It was found that A-H-GNs and luminol-AgNPs-GO exhibited excellent ECL activity. On this basis, a label-free ECL aptasensor for 2,4,6-trinitrotoluene (TNT) detection was developed based on bilayer structure of luminescence functionalized graphene hybrids consisting of A-H-GNs and luminol-AgNPs-GO. First, positively charged chitosan-coated A-H-GNs were modified on the surface of indium-doped tin oxide electrode by simple dripping and drying in the air; after that, the modified electrode was immersed in negatively charged luminol-AgNPs-GO modified with aptamer (apta-biotin-SA-luminol-AgNPs-GO) to form apta-biotin-SA-luminol-AgNPs-GO/CS-A-H-GNs/ITO electrode (i.e., aptasensor) by electrostatic interaction. In the presence of TNT, a remarkable decrease in ECL signals was observed due to the formation of aptamer-TNT complex. TNT could be detected based on the inhibition effect. The aptasensor exhibits a wide dynamic range from 1.0 × 10(-12) to 1.0 × 10(-9) g/mL, with a low detection limit of 6.3 × 10(-13) g/mL for the determination of TNT, which is superior to most previously reported bioassays for TNT. Moreover, the proposed aptasensor has been successfully applied to the detection of TNT in environmental water. It is sensitive, selective, and simple, avoiding complicated labeling and purification procedures. Due to the wide target recognition range of aptamer, this strategy provides a promising way to develop new aptasensor for other analytes.

Electrochemiluminescence Detection of TNT by Resonance Energy Transfer through the Formation of a TNT-Amine Complex

2,4,6-Trinitrotoluene (TNT) is a widely used nitroaromatic explosive with significant detrimental effects on the environment and human health. Its detection is of great importance. In this study, both electrochemiluminescence (ECL)-based detection of TNT through the formation of a TNT-amine complex and the detection of TNT through electrochemiluminescence resonance energy transfer (ECRET) are developed for the first time. 3-Aminopropyltriethoxysilane (APTES)-modified [Ru(phen)3](2+) (phen=1,10-phenanthroline)-doped silica nanoparticles (RuSiNPs) with uniform sizes of (73±3) nm were synthesized. TNT can interact with APTES-modified RuSiNPs through charge transfer from electron-rich amines in the RuSiNPs to the electron-deficient aromatic ring of TNT to form a red TNT-amine complex. The absorption spectrum of this complex overlaps with the ECL spectrum of the APTES-modified RuSiNPs/triethylamine system. As a result, ECL signals of the APTES-modified RuSiNPs/triethylamine system are turned off in the presence of TNT owing to resonance energy transfer from electrochemically excited RuSiNPs to the TNT-amine complex. This ECRET method has been successfully applied for the sensitive determination of TNT with a linear range from 1×10(-9) to 1×10(-6) M with a fast response time within 1 min. The limit of detection is 0.3 nM. The method exhibits good selectivity towards 2,4-dinitrotoluene, p-nitrotoluene, nitrobenzene, phenol, p-quinone, 8-hydroxyquinoline, p-phenylenediamine, K3[Fe(CN)6], Fe(3+), NO3(-), NO2(-), Cr(3+), Fe(2+), Pb(2+), SO3(2-), formaldehyde, oxalate, proline, and glycine.

Hybrid of non-selective quantum dots for simultaneous determination of TNT and 4-nitrophenol using multivariate chemometrics methods

The overall fluorescence of a hybrid of two non-selective quantum dots (CQDs and CdTe QDs) has been used for pattern-based discrimination of different analytes and simultaneous determination in a binary mixture of analytes.

Electrochemical Detection of TNT at Cobalt Phthalocyanine Mediated Screen‐Printed Electrodes and Application to Detection of Airborne Vapours

AbstractWe describe the use of cobalt phthalocyanine as a mediator to improve the sensitivity for the electrochemical detection of TNT. Commercial screen‐printed electrodes containing cobalt phthalocyanine were employed for determination of TNT. Improved sensitivities compared to screen‐printed carbon electrodes without phthalocyanine were observed, current response for cyclic voltammetric measurements at modified electrodes being at least double that of unmodified electrodes. A synergistic effect between oxygen and TNT reduction was also observed. Correlation between TNT concentrations and sensor output was observed between 0–200 µM TNT. Initial proof‐of‐concept experiments combining electrochemical determinations, with the use of an air‐sampling cyclone, are also reported.

Determination of TNT explosive based on its selectively interaction with creatinine-capped CdSe/ZnS quantum dots

Here, a creatinine-modified CdSe/ZnS quantum dots fluorescent probe has been prepared and used for sensing 2,4,6,-trinitrotoluene explosive (TNT). The proposed method is based on the selective interaction between creatinine and nitroaromatic compounds according to the well-known Jaffé reaction. The procedure for the synthesis of creatinine-CdSe/ZnS reagent is very simple and reproducible and its fluorescent characteristics are reported. We found that the presence of TNT quenches the original fluorescence of creatinine-QD according to the Stern–Volmer model. Under the working conditions, the calibration plot of Io/I versus concentration of TNT was linear in the range 10–300μgL−1 (R2=0.996). The mechanism interaction is discussed. The selectivity of fluorescence quenching of creatinine-QD for TNT has been evaluated. Finally, the potential application of the proposed methodology for the determination of TNT in spiked soils is demonstrated. For the analysis of soil samples a solid-liquid extraction is carried out and a four-point standard addition protocol is used to correct the matrix effect. The method, which is simple and rapid, allows the detection of 0.057μgg−1 of TNT in soil samples. This sensor could be a useful tool for environmental studies, a crucial topic for nanotechnology nowadays.

Two-dimensional molecular imprinting approach for the electrochemical detection of trinitrotoluene

In this work, we demonstrated a sensitive and selective electrochemical sensing protocol for the detection of TNT prepared from alkanethiols self-assembled on AuNPs modified glassy carbon (GC) electrode with preadsorbed templates of TNT. It demonstrated that the 2D molecular imprinting monolayers (MIMs) can provide a better site accessibility and lower mass-transfer resistance, while the AuNPs can enhance electrode conductivity, facilitate the electron transfer and increase the amount of TNT-imprinted sites. The prepared sensor showed not only high selectivity toward TNT in comparison to other similar nitroaromatic compounds (NACs), but also a wide linear range over TNT concentration from 4.0 × 10 −8 to 3.2 × 10 −6 M with a detection limit of 1.3 × 10 −8 M (S/N = 3). Moreover, the imprinted sensor has been applied to the determination of TNT in spiked environmental water samples and shows promise for fast and sensitive measurement of trace levels of TNT in real samples.

Selective colorimetric determination of TNT partitioned between an alkaline solution and a strongly basic Dowex 1-X8 anion exchanger

The Meisenheimer anions formed from TNT in KOH solutions in alcohol or acetone were used in screening tests for TNT among possible nitro-explosives. The same reaction was used for the spectrophotometric assay of TNT in soil by CRREL (Cold Regions Research & Engineering Laboratory of the U.S. Army) method, also known as Jenkins’ method, but the color stability was too dependent on the solution composition and the water tolerance was low, necessitating complete drying of soil samples (which may cause partial analyte decomposition) prior to analysis. This study reports the development of a colorimetric method based on the solid phase extraction (SPE) of the Meisenheimer anion formed from TNT and aqueous NaOH into a strongly basic anion exchange resin Dowex 1-X8 (OH − form). The orange-red color that developed both in the solid resin and solution phases was persistent for at least 1 h. The resin was let to swell in alcohol, washed first with 1 M aqueous NaOH, and then with H 2O before use. To 5 mL of 4–400 ppm TNT solutions in 1:1 (v/v) acetone–water, 0.5 mL of 5% NaOH was added, diluted to 50 mL with 1:1 acetone–water, and the resulting solutions (containing the orange-red Meisenheimer anion of TNT) were agitated at room temperature with 0.9 g resin for ≤50 min. TNT exhibited a reasonably constant distribution coefficient between the resin and aqueous phases. The absorbance of the filtered solutions was measured against a reagent blank at 500 nm. The TNT-loaded resins were regenerated with 1 M HCl containing sodium sulfite. The calibration line of filtrate absorbance versus analytical concentration was linear over two orders of magnitude between 0.4 and 40 ppm TNT in final solution. Unlike Jenkins’ method, the method was tolerant to 100-fold (by mass) of common soil anions like sulfate, nitrate, and chloride. The basic advantages of the developed colorimetric method over the similar CRREL/Jenkins’ method may be summarized as color stability, water and common ion tolerance, lowering of the LOD, and widening of the linear range. As opposed to Jenkins’ method, the charge-transfer bands characteristic to colorimetric detection were not obscured by the presence of water. The method is suitable for on-site applications, because the color developed in heterogenous solution was stabilized, and the method can be easily practiced with a portable colorimeter to large numbers of samples.