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

Highly sensitive chemiluminescence sensors for the detection and differentiation of chemical warfare agents

Highly sensitive chemiluminescence-based probes that effectively detect and differentiate between the extremely toxic real G- and V-type organophosphorus chemical warfare agents (OPCWAs) are presented. This straightforward approach does not require any instrumentation or light source; hence, it appears ideal for the future development of field colorimetric detectors.

A single recognition unit-based virtual sensor Array: Applying 3D fluorescence spectroscopy to inner filter effect-based sensing

A convenient, fast, low-cost detection and discrimination method is demanded for environmental monitoring but still it remains more technological challenges. Herein, we demonstrate that the inner filter effect (IFE), in combination with three-dimensional fluorescence spectroscopy, can offer a virtual sensor array (VSA) as apropersolution. And with the aid of pattern recognition techniques, it is feasible to recognize compounds with structural similarities economically and effectively. In this study, with the help of visual clustering plots of principal component analysis (PCA), a prediction model based on hierarchical strategy was made using support vector machine (SVM) method for the qualitative profiling of aromatic pollutants. The VSA was constructed by a single metal-organic framework (MOF) recognition unit (MOF-74 (Zn)) with the excitation wavelength as external regulatory factors. Pattern characteristics of four aromatics with very similar structures (phenylamine, chlorobenzene, nitrobenzene, and phenol), both single analyte and binary mixtures, were acquired. The primary constituents of multi-dimensional spectral signals were subsequently extracted and fed into a vector machine to construct a prediction model through 10-fold cross-validation optimization, resulting in a classification accuracy of 100% for single analytes and 96% for mixtures. Quantitative research has shown that, except for chlorobenzene, all three other analytes can be predicted in concentration within an acceptable error range, and the mixture can be predicted proportionally. Moreover, the VSA can be used to distinguish these pollutants in tap and river water also. We propose for the first time a new tack for the construction of VSA in a general manner, namely using three-dimensional full range fluorescence scanning for IFE based sensing to get multiple times of information resulting from different weak interaction between analyte and sensor for decision-making.

Differentiating Between V- and G-Series Nerve Agent and Simulant Vapours Using Fluorescent Film Responses

In-field rapid and reliable identification of nerve agents is critical for the protection of Defence and National Security personnel as well as communities. Fluorescence-based detectors can be portable and provide rapid detection of chemical threats. However, most current approaches cannot differentiate between dilute vapors of nerve agent classes and are susceptible to false positives due to the presence of common acids. Here a fluorescence-based method is shown for rapid differentiation between the V-series and phosphonofluoridate G-series nerve agents and avoids false positives due to common acids. Differentiation is achieved through harnessing two different mechanisms. Detection of the V-series is achieved using photoinduced hole transfer whereby the fluorescence of the sensing material is quenched in the presence of the V-series agent. The G-series is detected using a turn-on mechanism in which a silylated excited state intramolecular proton transfer sensing molecule is selectively deprotected by hydrogen fluoride, which is typically found as a contaminant and/or breakdown product in G-series agents such as sarin. The strategy provided discrimination between classes, as the sensor for the G-series agent class is insensitive to the V-series agent, and vice versa, and neither responded to common acids.

Fast and Selective Detection of Trace Chemical Warfare Agents Enabled by an ESIPT-Based Fluorescent Film Sensor

Reliable detection of airborne chemical warfare agents (CWAs) at the site and in real-time remains a challenge due to the rarity of miniaturized analytical tools. Herein, an o-carborane-functionalized benzothiazole derivative (PCBO) with excited-state intramolecular proton transfer (ESIPT) and AIE characteristics was synthesized. The PCBO-based film sensor showed a highly sensitive response to representative simulants of CWAs, and detection limits were found to be 1.0 mg·m^-3 for triphosgene, 6.0 mg·m^-3 for chloroethyl ethyl sulfide, and 0.2 mg·m^-3 for diethyl chlorophosphite. Moreover, the sensor showed great reusability (>100 cycles) and unprecedented response speed (<0.5 s). The excellent sensing performance was ascribed to the microenvironmental sensitivity of the sensing fluorophore, the porous adlayer structure of the film, and the specific binding of the fluorophore to the analytes. Furthermore, discrimination and identification of the examined CWA simulants were realized via the introduction of another fluorophore (HCBO)-based film. Importantly, a portable fluorescent CWA detector was built with the sensor as the key component, and its applicability was demonstrated by the successful detection of a typical CWA sample (Sarin). The present study indicates that fluorescent film sensors could satisfy reliable onsite and real-time detection of harmful chemicals.

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.