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Author(s): A. V. Braun [sup.1], M. F. Vokuev [sup.1], Y. V. Stavitskaya [sup.2], T. M. Baygildiev [sup.1], V. A. Yashkir [sup.2], I. V. Rybalchenko [sup.2], I. A. Rodin [sup.1] Author [...]

We developed a method for determining ethyl methylphosphonic, isopropyl methylphosphonic, isobutyl methylphosphonic, and pinacolyl methylphosphonic acids in human urine using gas chromatography with high-resolution mass spectrometry and preliminary derivatization with p-methoxyphenacyl bromide. All of the acids are specific hydrolysis products and biomarkers of nerve agents. Conditions of the derivatization reaction were optimized. Features and general patterns of the MS.sup.1 and MS.sup.2 spectra of derivatives acquired in electron and chemical ionization modes are revealed. The developed method achieved the limits of detection in the range from 20 to 70 ng/mL., Author(s): D. V. Oreshkin [sup.1] [sup.2], T. M. Baygildiev [sup.1], M. F. Vokuev [sup.1], A. V. Braun [sup.1] [sup.2], I. A. Godovikov [sup.3], I. V. Rybalchenko [sup.1] [sup.2], I. A. [...]

A multipurpose reagent, p-methoxyphenacyl bromide, is proposed for the derivatization of polar products of the degradation (markers) of nerve agents, which allows their determination by high-performance liquid chromatography with tandem mass spectrometric detection or by gas chromatography in combination with high-resolution mass spectrometry. The reaction conditions for the derivatization of alkylphosphonic and alkylmethylphosphonic acids with this reagent were optimized, the features and general patterns of the formation of MS.sup.1 and MS.sup.2 spectra of derivates were found, and the conditions for their chromatographic separation by two independent methods were selected. The limits of detection reached are in the range from 0.02 to 0.2 ng/mL for high-performance liquid chromatography with tandem mass spectrometric detection and from 10 to 50 ng/mL for gas chromatography with tandem mass spectrometric detection., Author(s): T. M. Baygildiev [sup.1], M. F. Vokuev [sup.1], D. V. Oreshkin [sup.2], A. V. Braun [sup.2], I. A. Godovikov [sup.3], I. V. Rybalchenko [sup.2], I. A. Rodin [sup.1] Author [...]

We proposed a method for determining the presence of trace amounts of adducts of isopropylmethylphosphonic acid (IMPA) and cyclohexylmethylphosphonic acid (CMPA), biomarkers of exposure to sarin and cyclosarin in a body, with a tripeptide (Tyr-Thr-Lys). The method is based on plasma trypsinolysis with the formation of stable adducts IMPA-Tyr-Thr-Lys and СMPA-Tyr-Thr-Lys and their detection by high-performance liquid chromatography (HPLC) with high-resolution tandem mass spectrometry detection. The following conditions for the sample preparation of human blood plasma exposed to sarin and cyclosarin were optimized: aliquot portion volume, enzymatic hydrolysis conditions, mass spectrometric detection (selection of optimal pairs of ion reactions and detection modes), and gradient elution programs in the HPLC separation of the test mixture. The limit of detection for sarin and cyclosarin in human blood plasma was 5 ng mL.sup.-1. The proposed approach was tested in the analysis of blood plasma samples submitted to analysis in the framework of the Fourth Official Biomedical Test of the Organization for the Prohibition of Chemical Weapons; the results showed good determination specificity., Author(s): T. M. Baygildiev [sup.1], A. V. Braun [sup.2], M. F. Vokuev [sup.1], A. N. Stavrianidi [sup.1], I. V. Rybalchenko [sup.2], I. A. Rodin [sup.1] Author Affiliations: (1) grid.14476.30, 0000 [...]

Optically transparent high-quality nanosized crystalline zinc ferrite thin films on different substrates have been synthesized by the decomposition of organic zinc and iron (III) compounds. According to scanning probe microscopy study, the films are 40-50 nm thick and their surface consists of densely spaced uniformly oriented crystallites with morphology depending on the substrate. X-ray diffraction analysis has shown that the films are polycrystalline and ZnFe2O4 has a cubic spinel structure. The dielectric constant lies in the range of 53 ÷ 54. The films are spontaneously polarized with a residual polarization of about 0.59 ÷ 0.69 μC⋅cm−2, the coercive field is (8 ÷ 12)·104 V/cm. [ABSTRACT FROM AUTHOR]

Nerve agents are organophosphorus compounds of the highest toxicity and danger. The production, transportation and use of these substances are prohibited by the Organization for the Prohibition of Chemical Weapons. Any fact of alleged use of nerve agents is a crime against humanity and must be investigated in detail by the world community. For this purpose, such analysis objects as biological fluids (urine, blood) and environmental objects (water, soil) are well studied. The current study demonstrates the possibility of using plants as a convenient material for retrospective analysis. Methyl phosphonic acid and some of its alkyl esters (ethyl, isopropyl, isobutyl, cyclohexyl, pinacolyl) were chosen as nerve agent metabolites. Hedera Helix growing in soil was used as a carrier of the markers. The selected markers were injected once in the soil and their content in the plant and soil was monitored for 4 weeks. A fast and simple way of sample homogenization with liquid nitrogen followed by ultrasonic liquid extraction was applied. The developed HPLC-MS/MS approach with the use of deuterated internal standards for quantitative analysis was validated. The research discovered that all the studied nerve agent markers could be detected and determined both in the soil and the plant for at least one month. The results indicate the promising use of plants as additional objects of analysis in investigation of incidents involving the use of chemical warfare agents., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The article provides a review of the literature on the development of chronic respiratory failure in patients with chronic cicatricial stenosis of the larynx and cervical trachea. The authors provide data on the etiology, pathogenetic features of the course of cicatricial stenosis of the larynx and trachea, the reasons for the development of chronic respiratory failure, the effect of hypoxemia on general metabolic processes in the body and on regeneration processes, as well as on methods of their correction and improvement of the postoperative period. The methods of respiratory impact on chronic respiratory failure in these patients are considered, based on the experience of a number of researchers and technical advances in recent years.

At present, there is a real threat of chemical warfare agents being used in terrorist acts and military clashes. Sulfur and nitrogen mustards are blister agents with high lethality and rapid disruption of armed forces. These highly poisonous substances are hydrolyzed to the characteristic marker compounds when released into the environment. Analysis of environmental objects allows to establish the fact of alleged use of chemical warfare agents and to reveal their type. However, water and soil samples are not always reliable for retrospective analysis. The resulting chemical warfare agent markers may be washed out from the application site over time by groundwaters or atmospheric condensations. This study shows the potential for using plants as a convenient material for retrospective analysis. Garden cress (Lepidium sativum) was chosen as a model plant for this purpose, since it can be easily and quickly grown hydroponically. The plants were cultivated in the environment of the selected markers to study an accumulation of these compounds by the plants. An effective and fast method of homogenization with subsequent ultrasonic extraction was applied. The extracts were analyzed using a specially developed and validated HPLC-MS/MS approach. Separation of the hydrophilic markers was carried out on a reversed-phase column with a polar endcapping. Sensitive mass spectrometric detection was performed in the multiple reaction monitoring mode. Achieved limits of detection for most markers were in the range of 2-40 ng mL -1 . It was discovered from the research that after the removal of markers from the growing medium the plants are able to store and concentrate these markers for at least 5 weeks, ensuring a high retrospectivity of the analysis. The obtained results indicate the perspective of using plants as additional objects of analysis during the investigation of incidents related to the use of chemical warfare agents. However, more complex plants and models should be studied in the future., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study a comprehensive approach for determination of low molecular organophosphorus nerve agent markers - highly polar alkylphosphonic acids and much less polar alkyl methylphosphonic acids is presented. Accurate, sensitive and simultaneous determination of the nerve agent markers in human urine was performed by ion chromatography and tandem mass spectrometry using deuterated internal standards. Analysis of the urine extracts was conducted on an anion-exchanger based on poly(styrene-co-divinylbenzene) substrate with a high degree of crosslinking and a covalently-bonded branched functional layer. The use of this type of column allowed achieving high values of retention factors for alkylphosphonic acids and alkyl methylphosphonic acids due to combination of anion-exchange and hydrophobic interactions between the analytes and the stationary phase of the column. Prior to the analysis, the urine samples were purified using anion-exchange cartridges for solid-phase extraction, and high recovery values were achieved for each analyte. The developed IC-MS/MS technique was validated for linearity, limit of detection, limit of quantification, precision and accuracy using two LC-MS/MS instruments. The proposed approach was successfully tested on the urine samples, provided by the Organisation for the Prohibition of Chemical Weapons in the frame of the 4th Biomedical Proficiency Test., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A direct approach for the determination of a specific hydrolysis product of organophosphorus nerve agents such as methylphosphonic acid (MPA) in urine by ion chromatography and tandem mass spectrometry (IC-MS/MS) has been developed. The first advantage of the proposed approach is a rapid and simple sample preparation, which does not require a large sample volume, complicated and laborious preconcentration and derivatization steps, and takes less than 7min per sample. The second advantage is the fast and selective IC determination of MPA carried out on a noncommercial anion exchanger based on a poly(styrene-co-divinylbenzene) (PS-DVB) substrate with a high degree of crosslinking and a covalently-bonded branched functional layer, which enables complete resolution of MPA from major urine matrix components and allows one to overcome matrix effects. Hyphenation of IC with tandem mass spectrometry results in highly sensitive and reliable MPA determination with the lowest detection limit (4ngmL -1 ) reported so far for HPLC determination of MPA in urine. The proposed approach is successfully applied for the analysis of urine from rats exposed to nonlethal doses of organophosphorus nerve agents such as sarin, soman, and VR in up to 13days after initial exposure, which shows the possibility to verify the nerve agent exposure after a long period of time., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Once exposed to the environment organophosphate nerve agents readily degrade by rapid hydrolysis to the corresponding alkyl methylphosphonic acids which do not exist in nature. These alkyl methylphosphonic acids are finally slowly hydrolyzed to methylphosphonic acid. Methylphosphonic acid is the most stable hydrolysis product of organophosphate nerve agents, persisting in environment for a long time. A highly sensitive method of methylphosphonic acid and alkyl methylphosphonic acids detection in dust and ground mixed samples has been developed and validated. The fact that alkyl methylphosphonic acids unlike methylphosphonic acid did not react with p-bromophenacyl bromide under chosen conditions was discovered. This allowed simultaneous chromatographic separation and mass spectrometric detection of derivatized methylphosphonic acid and underivatized alkyl methylphosphonic acids using HILIC-MS/MS method. Very simple sample pretreatment with high recoveries for each analyte was developed. Methylphosphonic acid pre-column derivate and alkyl methylphosphonic acids were detected using tandem mass spectrometry with electrospray ionization after hydrophilic interaction liquid chromatography separation. The developed approach allows achieving ultra-low detection limits: 200 pg mL(-1) for methylphosphonic acid, 70 pg mL(-1) for ethyl methylphosphonic acid, 8 pg mL(-1) for i-propyl methylphosphonic acid, 8 pg mL(-1) for i-butyl methylphosphonic acid, 5 pg mL(-1) for pinacolyl methylphosphonic acid in the extracts of dust and ground mixed samples. This approach was successfully applied to the dust and ground mixed samples from decommissioned plant for the production of chemical weapons., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A new sensitive rapid-separation liquid chromatography tandem mass spectrometry approach for the determination of thiodiglycolic acid (TDGA) in urine has been developed. The use of the "dilute-and-shoot" method helps to shorten the sample preparation stage and provides a sensitive and direct approach for TDGA determination in urine. Chromatographic separation of the analyte and other urine compounds was achieved using a reverse-phase liquid chromatography column with mobile phases consisting of 0.1% formic acid in water and acetonitrile in a gradient elution mode. For the identification and quantification of TDGA electrospray ionization-tandem mass spectrometry monitoring, two precursor-to-product ion transitions were used. The method demonstrates good linearity and has a detection limit of 50 ng mL⁻¹ in urine.

A sensitive screening method based on fast liquid chromatography tandem mass-spectrometry (RSLC-MS-MS) has shown the feasibility of separation and detection of low concentration β-lyase metabolites of sulfur mustard and of nerve agent phosphonic acids in urine. The analysis of these compounds is of interest because they are specific metabolites of the chemical warfare agents (CWAs), sulfur mustard (HD), sarin (GB), soman (GD), VX and Russian VX (RVX). The 'dilute-and-shoot' RSLC-MS-MS method provides a sensitive and direct approach for determining CWA exposure in non-extracted non-derivatized samples from urine. Chromatographic separation of the metabolites was achieved using a reverse phase column with gradient mobile phases consisting of 0.5% formic acid in water and acetonitrile. Identification and quantification of species were achieved using electrospray ionization-tandem mass-spectrometry monitoring two precursor-to-product ion transitions for each compound. The method demonstrates linearity over at least two orders of magnitude and had detection limits of 0.5 ng/mL in urine., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

A sensitive and simple method for the quantification and for the detection of 2-chlorovinylarsonous (CVAA) and 2-chlorovinylarsonic (CVAOA) acids was developed. CVAA and CVOA are important biological markers in human and rat urine specific to lewisite (chlorovinylarsonous chloride compounds) exposure. The developed assay was based on the use of solid-phase extraction (SPE) followed by liquid-chromatography coupled to electrospray ionization (negative ion-mode) low-energy collision dissociation-tandem mass spectrometry (ESI-CID-MS/MS). The method demonstrated linearity over at least three orders of magnitude and had a detection limit (LOD) of 0.5 ng/ml for CVAA and 3 ng/ml for CVAOA. The relative standard deviations for the quality control samples ranged from 6 to 11%. Application of this procedure was demonstrated in the lewisite animals exposure model. Rats were exposed intravenously by no lethal doses of lewisite and markers levels in urine samples were analyzed for 21 days post-exposure., (Copyright © 2011 Elsevier B.V. All rights reserved.)