Water-recyclable and reusable fluorescent sensors for nerve gas mimetic detection

Herein, the serendipitous discovery of two water-recyclable and reusable fluorescent sensors IMPC (cyan-blue-cyan) and IMPC-OH (green-blue-green) is reported for sensing nerve agent simulants diethylcyanophosphonate and diethylchlorophosphate, respectively, with high sensitivity, short response time, and low detection limits. The unique features of these probes are their regeneration with the addition of a green and cheap solvent, namely water in CHCl3, and ease of fabrication into a portable paper-strip system that can also be regenerated. Various spectroscopic studies were employed to understand the mechanism of sensing and regeneration of both probes; the results reveal that water plays a critical role in the hydrolysis of the adduct formed with DCNP and DCP, which enables the retrieval of the probe with its original fluorescence.

Chromogenic Detection of the Organophosphorus Nerve Agent Simulant DCP Mediated by Rhodium(II,II) Paddlewheel Complexes

Organophosphorus nerve agents (OPNAs) pose a great threat to humanity. Possessing extreme toxicity, rapid lethality, and an unassuming appearance, these chemical warfare agents must be quickly and selectively identified so that treatment can be administered to those affected. Chromogenic detection is the most convenient form of OPNA detection, but current methods suffer from false positives. Here, nitrogenous base adducts of dirhodium(II,II) acetate were synthesized and used as chromogenic detectors of diethyl chlorophosphate (DCP), an OPNA simulant. UV-vis spectrophotometry was used to evaluate the sensitivity and selectivity of the complexes in the detection of DCP. Visual limits of detection (LOD) for DCP were as low as 1.5 mM DCP, while UV-vis-based LODs were as low as 0.113 μM. The dirhodium(II,II) complexes were also tested with several potential interferents, none of which produced a visual color change that could be mistaken for OPNA response. Ultimately, the Rh2(OAc)4(1,8-diazabicyclo[5.4.0]undec-7-ene)2 complex showed the best combination of detection capability and interferent resistance. These results, when taken together, show that dirhodium(II,II) paddlewheel complexes with nitrogenous base adducts can produce instant, selective, and sensitive detection of DCP. It is our aim to further explore and apply this new motif to produce even more capable OPNA sensors.

Thin colorimetric film array for rapid and selective detection of v-type nerve agent mimic in potentially contaminated areas

The expeditious detection and quantification of V-series nerve agents (VX) on potentially contaminated surfaces are crucial for the prevention of regional conflict incidents, acts of terrorism, or illicit activities. However, the low volatility and high toxicity of VX make these tasks challenging. Herein, we designed two novel colorimetric thin polymeric films to rapidly and sensitively detect demeton-S, a VX mimic, in contaminated areas. The polymeric films were specifically engineered to include a coordination site for Au (III) ions. Initially, these films were coordinated with Au (III), causing a discernible alteration in color due to enhancement in intramolecular charge transfer process. In the presence of demeton-S, the Au (III) ligands in the films are displaced with demeton-S, resulting in the restoration of the original color of the film, as the enhanced intramolecular charge transfer process is inhibited and thereby serving as an indicator of the presence of demeton-S. The polymeric films exhibit remarkable selectivity toward demeton-S compared to G-type nerve agents and other interference. The reusability of the polymeric films for demeton-S detection was achieved owing to the reversibility of the films during the alternative exposure of Au (III) and demeton-S. The polymeric films demonstrated their applicability for demeton-S detection and quantification in several contaminated areas, including different water, soil, and skin, rendering them highly suitable for on-site measurements.

Highly selective and sensitive chromogenic recognition of sarin gas mimicking diethylchlorophosphate

The high-level toxic effects of organophosphate (OP) nerve agents severely threaten national security and public health. Generating trustworthy, accurate methods for quickly identifying these poisonous chemicals is urgently necessary. In this study, we have presented an azine-based colorimetric sensor (HBD) for the highly sensitive and selective identification of poisonous sarin gas surrogate diethylchlorophosphate (DCP). Our introduced sensor shows a purple color in contact with DCP, which is fully reversible upon the addition of triethylamine (TEA). The detection limit of our sensor for the toxic nerve agent mimic DCP is in the μM range. We have fabricated a test kit to verify the capability of HBD for on-the-spot identification of DCP to execute its practical use. To prove that HBD is an effective chemosensor, dip-stick investigation was conducted to detect DCP in the vaporous stage in the presence of different OPs, inorganic phosphates (IPs), and many other deadly analytes. A cellphone-based display method was also undertaken for on-the-spot recognition and measurement of DCP in isolated regions.

A benzoxazole-triphenylamine conjugated fluorogenic probe for specific detection of sarin gas mimic diethylchlorophosphate

In this study, an excellent chromo-fluorogenic PMPA probe, (E)-4-(((4-(benzoxazole-2-yl)phenyl)imino)methyl)-N,N-diphenylamine, is introduced for the detection of sarin gas mimic diethyl chlorophosphate (DCP) in solution and gaseous phases. On adding DCP into PMPA solution in a pure DMSO and water-DMSO (4 : 1) medium, it exhibits a hypsochromic shift from yellow to colorless and from no fluorescence to highly intense blue-violet photoluminescence via the formation of a phosphorylated PMPA-DCP product due to the inhibition of intramolecular charge transfer (ICT) and photoinduced electron transfer (PET) mechanism. The sensor could detect DCP in the presence of several other notorious guest analytes with a detection limit in the μM range. Moreover, to accomplish the on-spot detection of DCP and explore the practical applicability of the probe, a paper strip-based test kit, "dip-stick" method, and, more interestingly, a real sample analysis was demonstrated in spiked soil samples.

Fabrication of a re-useable ionic liquid-based colorimetric organo nanosensor for detection of nerve agents' stimulants

Nerve agents are highly poisonous organophosphorus chemicals, and the possibility of being used in terrorist attacks seriously threatens public safety. Thus, developing quick and straightforward detection techniques for these dangerous substances is paramount for the scientific communities. In this contribution, we have fabricated a sensitive and easily applicable ionic liquids (ILs) based colorimetric sensor for detecting various nerve agents' stimulants in solution and gas phases, respectively, based on methyl orange (MO)-based IL ([P66614]+[MO]-) derived from MO dye and trihexyltetradecylphosphonium chloride (P66614Cl) by a simple ion exchange mechanism. The developed [P66614]+[MO]- and water-suspended [P66614]+[MO]- nanoparticles are found to be very much sensitive to detecting various nerve agents' stimulants having detection limits in the μM range in any medium and could be identified based on the response times which is found to be superior to many chemosensors available in the literature. The naked eye observed a distinct color change from yellow to fuchsia in the presence of nerve agents' stimulants, which shows better sensitivity than the free organic indicator. Furthermore, a facile test strip with [P66614]+[MO]- and water-suspended [P66614]+[MO]- NPs has been fabricated that can achieve visual detection of various nerve agents' stimulants within the stockpiles of other analogous harmful analytes. Also, a dip-stick experiment has been performed to detect harmful toxic analytes vapor. The effectiveness of [P66614]+[MO]- and water-suspended [P66614]+[MO]- NPs in identifying and quantifying various nerve agents' stimulants demonstrated its potential for usage as a signal tool for real sample analysis.

A benzoxazole-based turn-on fluorosensor for rapid and sensitive detection of sarin surrogate, diethylchlorophosphate

A benzoxazole-based fluorosensor (IMP) has been synthesized and employed for the selective and sensitive detection of sarin surrogate, diethylchlorophosphate (DCP) in solution, and gas phase, respectively. Remarkable turn-on fluorescence is observed due to the introduction of DCP in the solution of IMP because of inhibition of the intramolecular charge transfer process and disruption of the excited state intramolecular proton transfer (ESIPT) mechanism. The synthesized IMP-based fluorescence sensor exhibits excellent selectivity, high sensitivity, and a wide linear range of 15-60 μM with a detection limit of 44 nM. Low-intense to highly intensified visible violet color could be seen by the naked eye under a portable 365 nm UV lamp due to the addition of DCP in the solution of IMP. IMP-stained paper strips-based test kit experiment has been demonstrated to detect traces of DCP in stockpiles of related analytes. A dip-stick experiment for the detection of DCP vapor has also been demonstrated. The effectiveness of IMP in detecting DCP established that it might be used as a signal tool for real sample analysis.

Recent advances in fluorescent and colorimetric chemosensors for the detection of chemical warfare agents: a legacy of the 21st century

Chemical warfare agents (CWAs) are among the most prominent threats to the human population, our peace, and social stability. Therefore, their detection and quantification are of utmost importance to ensure the security and protection of mankind. In recent years, significant developments have been made in supramolecular chemistry, analytical chemistry, and molecular sensors, which have improved our capability to detect CWAs. Fluorescent and colorimetric chemosensors are attractive tools that allow the selective, sensitive, cheap, portable, and real-time analysis of the potential presence of CWAs, where suitable combinations of selective recognition and transduction can be integrated. In this review, we provide a detailed discussion on recently reported molecular sensors with a specific focus on the sensing of each class of CWAs such as nerve agents, blister agents, blood agents, and other toxicants. We will also discuss the current technology used by military forces, and these discussions will include the type of instrumentation and established protocols. Finally, we will conclude this review with our outlook on the limitations and challenges in the area and summarize the potential of promising avenues for this field.

Enantiopure chiroptical probes for circular dichroism and absorbance based detection of nerve gas simulants

A series of oxovanadium(V) compounds 1-4 were prepared and explored as stereodynamic chiroptical probes to detect a simulant of sarin known as diethyl chlorophosphate (DCP) without any interference from the competing analytes. Simultaneous CD cum UV/vis based bimodal instant recognition of DCP using optically active probes is unprecedented. Upon fabricating the vanadium compound with a polymer has yielded a chiroptical membrane, which showed a change in its dichroic as well as colorimetric signals on interaction with DCP vapour at 1 ppm. EPR and UV/vis studies revealed an irreversible change of the CD-active V(V) to the CD-silent ternary V(V) species in presence of DCP via a transient V(IV) species. Nucleophilic attack of the alkoxo oxygen of 1-4 to the electrophilic P atom of DCP resulted in the formation of ternary V(V) compounds as confirmed by ⁵¹V/³¹P NMR.

A self-degradable hydrogel sensor for a nerve agent tabun surrogate through a self-propagating cascade

Nerve agents that irreversibly deactivate the enzyme acetylcholinesterase are extremely toxic weapons of mass destruction. Thus, developing methods to detect these lethal agents is important. To create an optical sensor for a surrogate of the nerve agent tabun, as well as a physical barrier that dissolves in response to this analyte, we devise a network hydrogel that decomposes via a self-propagating cascade. A Meldrums acid-derived linker is incorporated into a hydrogel that undergoes a declick reaction in response to thiols, thereby breaking network connections, which releases more thiols, propagating the response throughout the gel. A combination of chemical reactions triggered by the addition of the tabun mimic initiates the cascade. The dissolving barrier is used to release dyes, as well as nanocrystals that undergo a spontaneous aggregation. Thus, this sensing system for tabun generates a physical response and the delivery of chemical agents in response to an initial trigger.

Design and development of a prototype for specific naked-eye detection of blister and nerve agents

In view of the strong need to strengthen the national security arising from chemical terrorism, a rapid, specific, and onsite detection of chemical warfare agents (CWAs) employing a simple and easy-to-use kit is of utmost importance. Constant and sincere efforts are being carried out by the scientific community to find reliable techniques/methods for early warning detection. Herein, we designed a prototype technique in the form of a smart and portable chemical weapon detection kit (CWDK) to facilitate rapid and onsite detection. In this portable kit, a range of unique chemical probes were condensed to achieve the specific chromogenic and fluorogenic detection and discrimination of each member of blister and nerve agents. The embodiment of three chemical probes (Fc, SQ, and LH2) was eventually employed in a compact and flexible plastic packaging for detecting the presence of CWAs with the 'naked-eye' in the areas where laboratory services do not normally exist. The CWDK contains dye/reagent vials, sampling assembly, and a UV torch. The convenience and practicality of this technique suggest a great prospect for highly specific sensing of the complete class of CWAs with fast and accurate results in real-time scenarios with a sensitivity much below their lethal dose.

Chromo-fluorogenic sensors for chemical warfare agents in real-time analysis: journey towards accurate detection and differentiation

The existence of chemical weapons (blister and nerve agents) is an unfortunate reality of the modern world. The usage of these chemical agents by rogue states or terrorist groups has showcased their ugly faces in the past and even in recent years. Despite extensive and strenuous efforts by the Organization for the Prohibition of Chemical Weapons (OPCW) to eliminate chemical warfare agents (CWAs) by the prohibition of their production and the destruction of their stockpiles, many countries still possess them in enormous quantities. Given the potential threat from these lethal agents, it is imperative to have a foolproof chemical sensor and detection system, which should consist of readily deployable chemical probes that can operate with high specificity and sensitivity. Over the last decade, our group has been engaged in designing and developing novel field-deployable sensing techniques by exploring approaches based on supramolecular tools, which can result in excellent specificity, sensitivity, high speed, portability and low cost. In this article, I describe our group's journey and success stories in the development of chemical warfare detection protocols, detailing the range of unique chemical probes and methods explored to achieve the specific detection of individual agents under real environmental conditions. It is interesting to note that the combination of three molecular probes (SQ, Fc and LH2) could simply achieve the detection of all CWAs at room temperature in one go without the need for nonportable and expensive instruments. The ease and generality of these techniques/methods suggest great promise for the highly specific chemical sensing of almost the entire class of CWAs. In this paper, a brief introduction is first provided to present the basic chemistry related to CWAs and the importance of supramolecular chemistry in the design of new protocols with new insights. The manipulation of molecular probes is then debated towards the development of a system for the chromo-fluorogenic sensing of CWAs without interference from most relevant analytes. Finally, the outlook of open challenges and the future developments of this rapidly evolving field is discussed.

Freestanding and Flexible β-MnO2@Carbon Sheet for Application as a Highly Sensitive Dimethyl Methylphosphonate Sensor

Research on wearable sensor systems is mostly conducted on freestanding polymer substrates such as poly(dimethylsiloxane) and poly(ethylene terephthalate). However, the use of these polymers as substrates requires the introduction of transducer materials on their surface, which causes many problems related to the contact with the transducer components. In this study, we propose a freestanding flexible sensor electrode based on a β-MnO₂-decorated carbon nanofiber sheet (β-MnO₂@CNF) to detect dimethyl methylphosphonate (DMMP) as a nerve agent simulant. To introduce MnO₂ on the surface of the substrate, polypyrrole coated on poly(acrylonitrile) (PPy@PAN) was reacted with a MnO₂ precursor. Then, phase transfer of PPy@PAN and MnO₂ to carbon and β-MnO₂, respectively, was induced by heat treatment. The β-MnO₂@CNF sheet electrode showed excellent sensitivity toward the target analyte DMMP (down to 0.1 ppb), as well as high selectivity, reversibility, and stability.

Luminol-Based Turn-On Fluorescent Sensor for Selective and Sensitive Detection of Sulfur Mustard at Ambient Temperature

We have explored a novel turn-on fluorescence detection of sulfur mustard (SM) at "room temperature". The innovative protocol that uses the combination of luminol and an ionic liquid in water exhibits fluorescence detection of SM within seconds. In this simple, fast, and low-cost chemosensing method, luminol acts as the receptor as well as a signaling element, and the ionic liquid (1-ethyl-3-methylimidazolium dicyanamide) provides the requisite and polarizing medium to realize the detection at "room temperature". Interestingly, with a higher concentration of a probe (0.56 mM), SM sensing can be visualized with the naked eye, leading to the formation of a fluorescent green color within a minute, thus expanding the application of the developed sensing technique for chromo-fluorogenic detection of SM. Excellent selectivity, sensitivity (LOD: 6 ppm), and chemosensing at ambient temperature make this methodology completely field-deployable.

A Fluorogenic and Chromogenic Probe Distinguishes Fluoride Anions and Thiols: Implications for Discrimination of Fluoride-Containing G Series and Sulfur-Containing V Series Nerve Agents

A coumarin-based probe, FP2, was designed for the differential detection of fluoride anions and thiols, i.e., the corresponding nucleophilic substitution products from fluorine-containing G agents and sulfur-containing V agents, thus having the potential to discriminate between these two nerve agents. FP2 with two functional reaction groups, α, β-unsaturated ketone and silyl groups, can react selectively with fluoride anions and thiols at the μM level respectively. Intriguingly, in the THF solution, FP2 reacts with the fluoride anion but not with the thiol, whereas in the EtOH/HEPES solution, FP2 reacts with the thiol but not with the fluoride anion. As a result, FP2 can produce different fluorophores in the two detection solutions, thus displaying significant fluorescence changes. In addition, the FP2 detection system can show a significant color change from colorless to yellow within seconds when detecting fluoride anions in THF detection solutions, and from yellow to light blue when detecting thiols in EtOH/HEPES solutions, which will facilitate visual detection by emergency responders at the scene of an incident involving a nerve agent.

Selective detection of chemical warfare agents VX and Sarin by the short wavelength inner filter technique (SWIFT)

A novel SWIFT-based strategy for fluorimetric detection of practical amounts (minimal effective dose or lower) of chemical warfare agents is reported. This strategy employs readily available reagents and allows distinguishing between the V and G agents, as well as their discrimination from potential interferents.

Enhancing the selectivity of optical sensors using synthetic transmembrane ion transporters

Herein, we introduce a new method to optimize the properties of optical sensors, coined the transporter-liposome-fluorophore (TLF) approach. It is shown that this approach can greatly improve the selectivity of the sensor, increase the dynamic range and maintain the sensitivity of the original fluorophore.

A fluorescent probe bearing two reactive groups discriminates between fluoride-containing G series and sulfur-containing V series nerve agents

Herein, we present an approach to design a fluorescent molecule for detection and discrimination of fluoride-containing G series and sulfur-containing V series nerve agents. FP1 bearing two reactive groups can react with fluorides and thiols from the two types of nerve agents and generate different products with obvious and diverse fluorescences, which will be helpful when dealing with terrorist crises.

Decomposition of Chemical Warfare Agent Simulants Utilizing Pyrolyzed Cotton Balls as Wicks

A simple method to improve the thermal decomposition of chemical warfare agent simulants is reported. Utilizing pyrolyzed cotton balls as a substrate for the delivery of an incendiary agent into a bulk volume of chemical warfare agent simulants, significant enhancements in the burning rates were achieved with respect to either other wicks or the incendiary agent by itself. To perform the decomposition experiments and follow the reaction in real time, while still addressing the important safety considerations related to experiments involving chemical warfare agent simulants and incendiary agents, a simple instrument was assembled in a laboratory hood, where all experiments were performed. Under ambient conditions, this method was able to enhance the decomposition of simulants for both sulfur mustard (HD) and sarin (GB) chemical warfare agents. Overall, the proposed approach represents one of the simplest and more cost-effective ways to improve the decomposition of these dangerous substances, presenting options for field expedient and low-cost processes that could be applied in the near future to the safe destruction of an actual CWA.

A New Portable Colorimetric Sensor Based on RGB Chromaticity for Quantitative Determination of Sarin in Water

Background:

Sarin is a nerve agent which is lethal to people due to its high toxicity. According to its extreme toxicity, sarin, relatively lack of color, highly toxic, miscible in water, poses viable threats to potable water sources. Therefore, there is an urgent need for portable, rapid and yet reliable methods to monitor for adulteration of potable water sources by sarin on spot.

Methods:

A stock solution of 30 mg/L sarin was prepared daily by dissolving 300 μg of sarin in 10 mL isopropanol. A certain amount of sarin was added to the glass tube, and then o-dianisidine and hydrogen peroxide were added. The pH value of the solution was adjusted to 9.8. The solution was transferred to the test tube after 10 minutes. A test tube of 2 mL was placed between the light source and the RGB color sensor. The LED light source illuminates directly over the test tube while the RGB sensor obtained the generated spectral response. This RGB voltage output is connected to the ADC and microcontroller to convert these analog voltages to three digital data. This RGB digital data is linked to the microcomputer through the serial port that is interfaced with the user interface. The data thus obtained in the sensor can be processed to display the sarin concentration.

Results:

Under the optimum conditions as described above, the calibration curve of chromaticity value versus sarin concentration was linear in the range of 0.15 mg/L to 7.8 mg/L. According to the IUPAC definition, theoretical detection limits of this method were 0.147 mg/L and 0.140 mg/L for R and B values, respectively. The practical detection limit was 0.15 mg/L. The sensor was successfully applied to the determination of sarin in artificial water samples and the recoveries were between 86.0% to 95.9%.

Conclusion:

The results in the present work have demonstrated the feasibility to design a new portable colorimetric sensor based on the RGB chromaticity method for quantitative determination of sarin in water. The influences of chromogenic reagent, oxidant, reaction time, o-dianisidine concentration, hydrogen peroxide concentration, reaction temperature, pH on the chromaticity values were investigated. The results showed that the sensor possessed high selectivity, sensitivity and good repeatability. The method would be potentially applied to the analysis of other toxic compounds in environment, such as other chemical warfare agents.

Detection Papers with Metal Complexes with Triphenylmethane Dyes for the Detection of G-Series Nerve Agents (Sarin, Soman, Cyclosarin) in the Liquid Phase

The paper presents the results of the study of the possibilities of using color metal complexes to detect the presence of chemical warfare agents (CWA) in liquid or aerosol form. Aluminon/Fe3+ and Eriochrome Cyanine R/Cu2+ coordination complexes and their ability to detect CWA in liquid phase are discussed. Detection systems have been demonstrated on instances of simple detection papers exposed to drops of real CWAs. Detection papers showed a positive response to G-series nerve agents and vesicant lewisite. Other liquid CWA do not interfere and the systems are also resistant to common organic solvents and a wide range of industrial chemicals.

Detection Papers with Chromogenic Chemosensors for Direct Visual Detection and Distinction of Liquid Chemical Warfare Agents

This work provides a summary of our results in the area of the experimental development of detection paper for the detection of liquid phase chemical warfare agents (drops, aerosol), the presence of which is demonstrated by the development of characteristic coloring visible to the naked eye. The basis of the detection paper is a cellulose carrier saturated with the dithienobenzotropone monomer (RM1a)–chromogenic chemosensor sensitive to nerve agents of the G type, blister agent lewisite, or choking agent diphosgene. We achieve a higher coloring brilliance and the limit certain interferences by using this chemosensor in the mix of the o-phenylendiamine-pyronine (PY-OPD). We prove that the addition of the Bromocresol Green pH indicator even enables detection of nerve agents of the V type, or, nitrogen mustards, while keeping a high stability of the detection paper and its functions for other chemical warfare agents. We resolve the resistance against the undesirable influence of water by providing a hydrophobic treatment of the carrier surface.

Ultrasensitive Detection of Sulfur Mustard via Differential Noncovalent Interactions

In this work, we fabricate two types of hierarchical microspheres, i.e., one coassembled from two fluorene-based oligomers (1 and 2) and one self-assembled from a fluorene-based oligomer (1), for ultrasensitive and selective detection of trace sulfur mustard (SM) vapor. On the basis of distinct fluorescence responses of 1-2 coassembled and individual 1 hierarchical microspheres that originate from differential noncovalent interactions between analytes and these sensors, SM vapor can be ultrasensitively detected (30 ppb) and easily discriminated from various sulfides and other potential interferents. Our work that utilizes differential noncovalent interactions to give sensitive and selective fluorescence response patterns represents a new detection approach for SM and other hazardous chemicals.

Organoiridium(III) Complexes as Luminescence Color Switching Probes for Selective Detection of Nerve Agent Simulant in Solution and Vapor Phase

In this work, cationic organoiridium(III) complex based photoluminescent (PL) probes have been developed to selectively detect the chemical warfare nerve agent mimic, diethyl chlorophosphate(DCP) at nanomolar range by distinct bright green to orange-red luminescence color switching (on-off-on) in solution as well as in the vapor phase. Interference of other chemical warfare agents (CWAs) and their mimics was not observed either by PL spectroscopy or with the naked-eye in solution and gas phase. The detection was attained via a simultaneous nucleophilic attack of two -OH groups of the 4,7-dihydroxy-1,10-phenanthroline ligand with DCP by forming bulkier phosphotriester. The detailed reaction mechanism was established through extensive ¹H NMR titration, ³¹P NMR, and ESI-MS analysis. Finally, a test paper strip and solid poly(ethylene oxide) (PEO) film with iridium(III) complex 1[PF₆] were fabricated for the vapor-phase detection of DCP. The solution and vapor-phase detection properties of these luminescent Ir(III) complexes can offer a worthy approach into the design of new metal complex based PL switching probes for chemical warfare agents.

Photo-induced formation of organic nanoparticles possessing enhanced affinities for complexing nerve agent mimics

Organic nanoparticles, composed of molecular baskets, could act as nanocarriers for selective “mopping” of toxic CWAs or pesticides, after being assembled by a light stimulus.

Amplified Detection of Chemical Warfare Agents Using Two-Dimensional Chemical Potential Gradients

Chemical warfare agents such as sarin are highly toxic, and detection of even trace levels is important. Using a hydrogel film containing a built-in two-dimensional chemical potential gradient, we demonstrate the detection of a sarin simulant under conditions potentially as low as a level 1 (6.90 × 10^-9 mg/cm³ for 10 min) Acute Exposure Guideline Level sarin exposure. Specifically, the sarin simulant diisopropyl fluorophosphate (DFP) is aerosol-deposited on a hydrogel film containing a built-in ionic chemical gradient and the enzyme, diisopropyl fluorophosphatase (DFPase). DFPase degrades the DFP, releasing fluoride ions. The fluoride ions are then concentrated by the gradient to a miniature electrochemical sensor embedded in the hydrogel providing a 30-fold amplification of the fluoride ion signal, which is an indication of exposure to DFP, relative to a gradient-free system. This method is general for agents which hydrolyze into chemically detectable ionic species.

A novel high-performance liquid chromatography-fluorescence analysis coupled with in situ degradation-derivatization technique for quantitation of organophosphorus thioester pesticide residues in tea

A novel high-performance liquid chromatography-fluorescence analysis in combination with in situ degradation-derivatization (ISD-D) technique was developed for simultaneous determination of seven organophosphorus thioester pesticides (OPTPs) in tea. The ISD-D technique was based on degradation of OPTPs by a nucleophilic substitution reaction between phenylbutane-1,2,3-trione-2-oxime and OPTPs, which can give thiol degradation products (DPs). The thiol DPs obtained were derivatized with the novel derivatization reagent N-(4-(carbazole-9-yl)-phenyl)-N-maleimide (NCPM) in a syringe. Attractively, NCPM itself did not fluoresce, whereas the derivatives of the thiol DPs fluoresced intensely, with excitation and emission maxima at 290 nm and 368 nm, respectively, which extraordinary reduced the background interference and increased the detection sensitivity for thiol DPs. Excellent linearity (R² > 0.995) for all OPTPs was achieved, with limits of detection and limits of quantitation ranging from 0.23 to 0.45 μg/kg and from 0.75 to 1.43 μg/kg, respectively. Satisfactory recoveries ranging from 90.5% to 96.0% were obtained for all OPTPs. The ISD-D technique provided a novel and sensitive strategy for quantitation of trace amounts of OPTPs in real samples. Graphical abstract ᅟ.

Real time detection of the nerve agent simulant diethylchlorophosphate by nonfluorophoric small molecules generating a cyclization-induced fluorogenic response

Herein, we report the detection of DCP by nonfluorophoric small molecules.