Methods of extraction-spectrophotometric determination of tris(2-chloroethyl)amine using nine acid dyes from the groups of sulfonephthaleins, sulfonated anthraquinones, and azo dyes have been developed. These procedures are based on the formation of the ion associates of the reactants and their extraction into chloroform. The conditions of the determination were optimized to determine the optimal pH for extraction from the water phase, the optimal excess of the dye, and the time needed for the extraction. The limits of detection and determination, the molar absorptivities of ion associates, extraction efficiency, distribution ratio, and conditional extraction constants for the separate procedures of determination were calculated. Of the studied acid dyes, the most suitable agents for determining the analyte were bromothymol blue and Acid Blue 129. These procedures are relatively undemanding in terms of time and instruments required and can be applied in field analysis of nitrogen mustards.

In this work we observe the reactions of selected agents fentanyl and its derivatives alfentanil, remifentanil and sufentanil with a specific reagent resulting in the creation of ion pairs and we verify the possibility of reliable determination of those agents by the extraction spectrophotometry method in the sphere of visible radiation. The procedure is based on protonation of agents in the acid environment and their extraction in the form of an associate with the acid dye anion into an organic phase immiscible with water – chloroform. The ion associates of fentanyl and its derivatives with Acid Red 88 absorb the light at a maximum of λmax 518 nm.

Methods of extraction-spectrophotometric determination of tris(2-chloroethyl)amine using nine acid dyes from the groups of sulfonephthaleins, sulfonated anthraquinones, and azo dyes have been developed. These procedures are based on the formation of the ion associates of the reactants and their extraction into chloroform. The conditions of the determination were optimized to determine the optimal pH for extraction from the water phase, the optimal excess of the dye, and the time needed for the extraction. The limits of detection and determination, the molar absorptivities of ion associates, extraction efficiency, distribution ratio, and conditional extraction constants for the separate procedures of determination were calculated. Of the studied acid dyes, the most suitable agents for determining the analyte were bromothymol blue and Acid Blue 129. These procedures are relatively undemanding in terms of time and instruments required and can be applied in field analysis of nitrogen mustards.

In a polar environment, tris(2-chloroethyl)amine molecule undergoes isomerization when forming N,N-bis(2-chloroethyl)aziridinium cation as a reactive intermediate. New methods were developed to spectrophotometrically determine tris(2-chloroethyl)amine in the form of aziridinium cation extraction using 4 sulfonephthaleins—bromothymol blue, thymol blue, bromoxylenol blue, and bromocresol green. The developed methods, reflecting potent electrophilic properties of the analyte, are based on the formation of extractable ion pairs between the aziridinium cation and a quinoid anion form of a sulfonephthalein. Chloroform was used as the solvent for extraction from the water phase. The conditions of the methods were optimised by determining the suitable pH (8.5) of a buffer and the concentration of sulfonephthaleins as reagents. The dependence of the reaction time in the water phase was found to be 10 min. The composition of the ion pairs was found to be 1:1 by in all cases and the conditional extraction constant of the complexes were calculated. The detection and determination limits of separate procedures were ascertained. Best results (detection limit 3.5 µg ml−1 and determination limit 11.6 µg ml−1) were obtained using bromothymol blue. The methods were empirically compared with a group spectrophotometric method to determine alkyl halides using the alkalized water–ethanol solution of thymolphthalein. Relatively low interferences of other nitrogen mustards and sulfur mustard were recorded. The interaction mechanism—ion association—was validated.

A simple colorimetric biosensor, which uses the modified Ellman's reaction, enables selective analysis of nerve agents based on a different ability of bispyridinium oximes to reactivate enzyme-inhibitor complexes in the phase before dealkylation.The analysis was made based on spectral data of reflectance of the surface of a cotton cloth reaction zone of biosensor with immobilized and stabilized enzyme after inhibition and subsequent reactivation.The evaluation of measured data was made based on a method of artificial neuronal networks.The individual inhibitors from the groups of three nerve agents were identified: sarin, soman, tabun, cyclosarin, agent VX and its Russian analogue, R-33.

This article deals with a detection of nerve agents. A photocolorimetric biosensor was designed for the detection of this group of cholinesterase inhibitors. This biosensor utilizes the enzyme butyrylcholinesterase. Ellman's modification of the cholinesterase reaction was used for the determination. To test the detection ability of the proposed cholinesterase detection means, tabun, sarin, soman, cyclosarin, agent VX and R33 were used. The detector was able to detect these substances in the air at very low concentrations (5.79·10–8 – 4.33·10–7 mg L–1, depending on the type of inhibitor).

This article deals with a detection of nerve agents. A photocolorimetric biosensor was designed for the detection of this group of cholinesterase inhibitors. This biosensor utilizes the enzyme butyrylcholinesterase. Ellman's modification of the cholinesterase reaction was used for the determination. To test the detection ability of the proposed cholinesterase detection means, tabun, sarin, soman, cyclosarin, agent VX and R33 were used. The detector was able to detect these substances in the air at very low concentrations (5.79.10(-8) - 4.33.10(-7) mg L-1, depending on the type of inhibitor).

Procedures for the extraction-spectrophotometric determination of tris(2-chloroethyl)amine, an alkylating agent known as a drug as well as a chemical warfare agent (nitrogen mustard HN-3), with 7 acid-base indicators of a triphenylmethane lactone type, phthaleins, were developed. Representatives of phthaleins without an oxygen bridge (thymolphthalein, o-cresolphthalein, naphtholphthalein) and with an oxygen bridge (fluorescein, 2',7'-dichlorofluorescein, eosin B and eosin Y) were used. The methods were based on the formation of ion pair complexes. Chloroform was used as a non-polar solvent for an extraction. The conditions to determine were optimized for the optimal pH of the buffer and the concentration of a phthalein as a reagent. The dependence on the reaction time in a water phase and the stoichiometry of extraction products were studied. The detection limits and the limits of the determination of separate procedures and conditional extraction constants were determined. Comparison with the spectrophotometric method of the group determination of alkyl halides and acyl halides using alkaline ethanol-water solution of thymolphthalein, the so-called T-135 agent, was conducted. While studying the selectivity, the possible interference of bis(2-chloroethyl)sulphide and 3 nitrogen mustards in the proposed procedures were verified. Copyright © 2016 John Wiley & Sons, Ltd.

Methods of determination of fentanyl, alfentanil, remifentanil and sufentanil were developed based on their ability to form coloured associates with acid dyes which can be extracted chloroform. Crocein Orange and Amido Black dyes produce the 1: 1 and 2: 1 associates at 485 nm and 626 nm, respectively.

The ability of the examined compounds to create ion pairs with the selected anionic dyes, allows their determination by the method of extraction spectrophotometry in the visible radiation.These ion pairs are extractable with an organic solvent immiscible with water.The procedure is based on protonisation of the studied compounds in acidic environment, and consequently their extraction in the form of associate with the anion of the acid dye into the organic phase, in this case in chloroform.Mentioned methods of analysis may be advantageously used for simple and express determination of fentanyl, alfentanil and remifentanil.

To detect nerve agents in practice, the analytical methods such as gas, liquid and thin-layer chromatography, mass spectrometry or capillary electrophoresis are usually used. Apart from these analytical methods, we developed an analytical device (tape photocolorimetric biosensor) based on the modified Ellman's cholinesterase biochemical reaction for multidetection of cholinergic organophosphorus compounds. Enzyme butyrylcholinesterase was used as a biorecognizing component and its activity was evaluated by red, blue, green (RGB) sensor. This method eliminates errors in the evaluation and provides automatic data collection with their subsequent evaluation. The unique method of dosing allows appropriate dispensing of reagents in microlitres volumes and the whole system is simple to operate. Suitability of the constructed biosensors was evaluated using the six organophosphates (Tabun, sarin, Soman, cyclosin, VX and R33 compound). Biosensor showed the ability to measure substances at concentrations ranging between similar to 1 x 10(-8) mg/l - 1 x 10(-6) mg/l in the air, according to their inhibition effect.

Construction of Detehit (nerve-agent detector), a colorimetric biosensor of nerve agents, enables its utilization for selective analysis of nerve agents based on the different ability of nucleophilic reagents to reactivate enzyme-inhibitor complexes in the phase before dealkylation. For this purpose mono-and bispyridinium aldoximes, common in treatment of nerve agent poisoning, are used.For a positive identification of a pair of organophosphates, a neural network analysis was used. The analysis was processed based on spectral data of the intensity of color changes of the surface of a cotton cloth reaction zone with immobilized and stabilized enzyme acetylcholinesterase. Color changes are based on Ellman's reaction. Intensity of these changes depends on activity of the enzyme after inhibition and reactivation of enzyme-inhibitor complex. The following nerve agents were identified: sarin, soman, tabun, cyclosarin, VX, and R-33.

A brief overview of the history of modern chemical weapons with emphasis on current chemical warfare agents (CWA). Some attempts at finding toxic compounds as potential CWA are mentioned. Recent CWA, V-series nerve agents, binary CWA and compounds with increased toxic effects are accented. A new category of CWA, fast-acting opioid anesthetics of the fentanyl type used as legal antiterrorism means is documented on the Dubrovka 2002 event.

The article describes the history and current importance of detection tubes for detection of chemical warfare agents, with stress put on their integration in the system of modern field analysis. The central part of the article is acquaintance with the results obtained in research, development and production of detection tubes in the period 1993-2008. Selected detection tubes for nerve, blister and choking agents as well as generally toxic and incapacitating (irritating and psychoactive) agents are described. A new chemical detector (CH-5) introduced to armament of the Czech Army is also mentioned. Further development in this field is discussed.

A simple visual and tristimulus colorimetric method (three-dimensional system CIE-L*a*b*) for the determination of trace amounts of hydrogen cyanide in air has been developed. The method is based on the suction of hydrogen cyanide through a chlorinating cartridge where cyanogen chloride is formed, which is further driven to an indicator disc made of a modified cotton fabric. This indicator disc is placed into an adapter. Prior to analysis, the disc is saturated with a chromogenic reagent, a solution of 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and 4-benzylpyridine in ethanol. In the presence of hydrogen cyanide (cyanogen chloride), a pink coloration emerges on the indicator disc, the intensity of which is evaluated either visually or by use of a tristimulus colorimeter. The detection limit is 0.1 mg m-3. The method is mainly suitable for mobile field analyses. It was applied for the CHP-5 chemical agent detector introduced into the equipment of the Czech Army corps.

Reactivation efficacy of three homologous and three isomeric series of pralidoxime-type reactivators with aldoxime group in position 2, 3 and 4 of the heterocycle was tested in reactivation of tabun-inhibited AChE. The experiments were performed with immobilized and stabilized porcine brain AChE. The enzyme acticity was measured by Ellman method. Reactivation efficacy was determined by measurement of indicator fabric coloration intensity as a measure of AChE activity. Of the studied group of nine reactivators, isomers with the functional group in position 2 were the most effective. The highest value (30 %) for reactivation of inhibited AChE was found for 2PAE after treatment for 15 min at concentration 0.5 mg/cm(3). The efficacy of the isomers decreased in the order ortho > para > meta. No marked effect on the efficacy of the reactivators was observed on prolongation of the reactivation time. The reactivators efficacy decreased with decreasing concentration of their solutions.

Reactivation with bis quaternary aldoxime HI-6, chemical formula 1-(2-hydroxyamino-methylpyridinium)-3-(4-carbamoylpyridinium)-2-oxapropane dichloride of immobilized enzyme acetylcholinesterase inhibited by nerve agent type "G" was studied. This aldoxime is effective in reactivation of sarin-inhibited acetylcholinesterase. Substantially lower reactivation potency was observed with cyclosarin-inhibited enzyme and almost no effect was found for that acetylcholinesterase is the enzyme complex. HI 6 is completely ineffective towards the soman-inhibited enzyme: After a 2-minute inhibition of the enzyme with soman no ability to define reactivator the inhibited enzymes and complexes.

OBJECTIVES:Quantification of efficacy of monopyridinium isomers and homologs derived from clinically used Pralidoxime within reactivation of acetylcholinesterase inhibited with organophosphorus nerve agents.METHODS:This work uses the colorimetric biosensor called Detehit - cotton cloth with immobilized enzyme acetylcholinesterase. Biosensor is based on the modificated Ellman's method.RESULTS:The highest reactivation was observed with sarin-inhibited acetylcholinesterase. Substantially lower reactivation was found with the cyclosarin-inhibited enzyme whereas AChE, inhibited by soman could not be effectively reactivated under the given conditions (enzyme inhibition for 2 minutes and subsequent treatment with the reactivator for 15 minutes).CONCLUSION:Our work gives comparison of efficacy of reactivators in dependence on the length of alkylene chain and position of aldoxime functional group. Evaluation of effectivity of aldoxime reactivators is provided by simple means. The method allows rapid in vitro evaluation of the reactivators without being disturbed by excess of the organophosphate or reactivator.

We studied issues of organophosphorus agents’ analysis. Immobilised enzyme–inhibitors complexes (e.g. acetylcholinesterase-organophosphate nerve agent) were studied with modified Ellman’s biochemical method utilised for assessment of acetylcholinesterase activity. Biochemical reactions are widespread and they are the most frequent used analytical methods for determination of nerve agents. This modified method is based on the nucleophilic reactions of mono- and bispyridinium aldoximes of a type 2-PAM, MMB-4 and HI-6, their homologues and isomers with enzyme–inhibitor complexes. The procedure for a gradual analysis of G and V type, Sarin, Cyclohexylsarin, Soman, Tabun, agent VX and R-33 was proposed in terms of studied nucleophilic substitution reactions quantification results. This method enables selective determination of these chemical warfare agents. A gradual analysis was evaluated by statistic method of probabilistic calculus. This type of analysis can be used for assessment of acetylcholinesterase inhibitors in very low concentrations close to hygienic limits.

A detector tube for approximate determination of phosgene, hydrogen cyanide, and cyanogen chloride in air has been described. The tube has been designed for the instant detection of harmful substances and continuous air control. The presence of harmful substances in air was detected visually on the basis of coloration of a polyfunctional indication layer, or by performing a 3D reflectance spectrophotometric measurement in the CIE-L*a*b* system. Visual limit of detection in 1 dm3 air sample was 0.1 mg m -3 for phosgene and 0.2 mg m -3 for hydrogen cyanide (cyanogen chloride).