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Unsymmetrical dimethylhydrazine (UDMH, heptyl) and its derivatives are used in the rocket and space industry as components of rocket fuel. UDMH is a highly toxic compound exhibiting irritant, hepatotoxic, and neurotoxic properties. In this study, the toxic effect of heptyl on isolated rat heart and lymphatic vessels was demonstrated. Acute exposure to UDMH leads to vasoconstriction of the coronary vessels of the isolated heart and pronounced stimulation of isolated lymphangions starting from the concentration of 10-4 M. The changes are dose-dependent. After exposure to UDMH in high concentrations (10-2 M), the changes in the functional parameters became irreversible. The obtained results provide evidence for the organ-specific effect of UDMH on visceral muscle organs. [ABSTRACT FROM AUTHOR]

Abstract—The behavior of unsymmetrical dimethylhydrazine (UDMH), a highly toxic rocket fuel, has been studied in a supercritical water medium within a temperature range of 400–650°C by electrospray ionization high-resolution mass spectrometry. It has been established that thermal transformation leads to the formation of a wide range of products, including at least 350–400 nitrogen-containing compounds of CHN and CHNO-classes. The main products are nitrogen-containing heterocyclic compounds containing from one to three nitrogen atoms. Based on the accurate masses, the tentative identification of the most important components is given. It has been shown that 1-methyl-1H-1,2,4-triazole predominates among the transformation products at a temperature of 650°C; in this case, the predominant fraction of UDMH is converted into gaseous nitrogen. [ABSTRACT FROM AUTHOR]

Abstract: Products of the interaction of 1,1-dimethylhydrazine with nitrogen dioxide in an aqueous solution are characterized by high-resolution mass spectrometry with electrospray ionization. It was found that more than 200 compounds of CHO, CHN, and CHNO classes formed in the reaction; the main component is extremely dangerous N-nitrosodimethylamine. Among the products of the transformation of 1,1-dimethylhydrazine, N-nitrosodibutylamine is identified for the first time. The results obtained are of importance for understanding processes of the transformation of rocket fuel in surface and ground waters at the places of impact of spent rocket stages containing both the propellant and the oxidant. [ABSTRACT FROM AUTHOR]

Photocatalysis technology could utilize solar energy to degrade many toxic pollutants and provides possibility to deal with unsymmetrical dimethylhydrazine (UDMH) wastewater with less energy consumption. In this study, well-aligned TiO nanorod arrays (TiO NRAs) were grown directly on transparent conductive glass (FTO) via a hydrothermal method, and TiO NRAs/CdS heterostructure films were prepared by decorating TiO NRAs with CdS nanoparticles through successive ion layer adsorption and reaction (SILAR). Under visible light, the TiO NRAs/CdS heterostructure displays enhanced photodegrading capacity compared with the bare TiO NRAs, and the highest photodegradation rate, 27.5% higher than that of the bare TiO NRAs, was achieved by the sample with 15 SILAR cycles. Additionally, the solution pH had some influence on the degradation process, which shows that the best degradation rate can be achieved in the neutral solution (pH is ca. 7.2), and the photodegradation process can be better in alkaline solution than in the acid solution. Moreover, the visible photocatalytic stability of the TiO NRAs/CdS sample was investigated. Finally, the underlying photocatalytic mechanism was discussed according to the photoelectrochemical and photoluminescence results. [ABSTRACT FROM AUTHOR]

Snow cover contamination is assessed in the impact areas of the first stage of the expandable launch system Proton in Central Kazakhstan. It was revealed that the chemical effect ofpropellants on the snow cover is local. The increase in the content of the following high-toxic substances in the snow was registered: unsymmetrical dimethylhydrazine, nitrosodimethylamine, and nitrate and nitrite ions. The most part of the pollutants is localized in the upper 5-cm snow layer. Nitrogen tetroxide decreases the value of pH, and unsymmetrical dimethylhydrazine increases it. The inflow of calcareous soil particles to the atmosphere and their subsequent fallout result in the alkalization of snow and in the neutralization of acidification by nitrogen tetroxide accompanied by the formation ofthe salts of nitric acid and nitrous acid. [ABSTRACT FROM AUTHOR]

A procedure has been developed for the determination of unsymmetrical dimethylhydrazine (UDMH) based on precolumn derivatization with glyoxal and determination of the produced derivative, mono-1,1-dimethylhydrazone of glyoxal, by reversed-phase HPLC ( RP-HPLC) with UV detection at 305 nm. It has been demonstrated that the reaction of UDMH with an excess of glyoxal in solution quantitatively yields one stable product within 20 min at 25°C at pH 3.5. To increase the sensitivity of UDMH determination it has been proposed to perform solid-phase extraction preconcentration of the derivative from a 25-mL sample portion on cartridges containing Strata SDB-L polymer adsorbent. The analytical range of UDMH determination in water is 0.5-10000 μg/L or 0.01-20 μg/L using preconcentration. The relative standard deviations of UDMH determination ( n = 3) do not exceed 0.12 and 0.25 without and with preconcentration, respectively. The accuracy of UDMH determination is confirmed by the analysis of spiked samples and by RP-HPLC determination with preliminary derivatization with 4-nitrobenzaldehyde as independent method. [ABSTRACT FROM AUTHOR]

The conditions of the simultaneous determination of unsymmetrical dimethylhydrazine (UDMH) and products of its transformation in aqueous solutions with ion and ion-pair chromatography and mass-spectrometric detection in the electrospray ionization mode have been selected. It has been shown that up to seven components may be determined within the limits of detection at the μg/L level. The application of the developed methods to the analysis of solutions with an initial UDMH concentration of 500 mg/L that had undergone spontaneous oxidation by atmospheric oxygen has been demonstrated. The accumulation of formic acid dimethylhydrazide, 1-methyl-1,2,4-triazole and dimethylamine has been found. [ABSTRACT FROM AUTHOR]

It is shown that, for a correct determination of the total concentration of unsymmetrical dimethylhydrazine ( UDMH) in soil, it is necessary to consider the simultaneous presence of active products of its transformation, capable of hydrolysis to the parent compound, such as formic acid 1,1-dimethylhydrazide ( FADMH). A comparative study is performed of the methods known in the literature for sample preparation to select conditions for the quantitative extraction of UDMH bonded by various mechanisms to organic and mineral fractions of soil, as well as FADMH as one of the most common active transformation products. It is found that the distillation with a 40% NaOH solution with an addition of NaS enables the quantitative recovery of UDMH and FADMH from soils of all types and the determination of the maximum concentration of UDMH in the analysis of real samples of contaminated soils, which allows us to recommend this option to determine the total concentration of UDMH. [ABSTRACT FROM AUTHOR]

The gas chromatography-mass spectrometry technique was used to investigate the composition of the reaction products of unsymmetrical dimethylhydrazine with a potassium permanganate and potassium permanganate-hydrogen peroxide mixture. If the water contamination level is within 50 threshold limit values (TLV) (1 mg/ml), the proposed detoxication method utilizing potassium permanganate in combination with hydrogen peroxide allows for the reduction of the UDMH concentration to a safe level without the accumulation of transformation products. The detoxication of aqueous solutions with significant UDMH concentrations (up to 50000 TLV) (1 g/l) with potassium permanganate alone or in combination with hydrogen peroxide reduces the UDMH concentration to a safe level, but UDMH transformation products, including the extremely toxic nitrozodimethylamine, are accumulated in the solution. [ABSTRACT FROM AUTHOR]

Procedures are developed on the basis of liquid chromatography/mass spectrometry for determining the transformation products of unsymmetrical dimethylhydrazine in soils: formic acid dimethylhydrazide (1-formyl-2,2-dimethylhydrazine, analytical range 0.01-20 mg/kg), 1-methyl-1,2,4-triazole (analytical range 0.05-100 mg/kg), 1,1-dimethylguanidine (analytical range 0.05-100 mg/kg), and dimethylamine (analytical range 0.25-250 mg/kg). The measurements were performed in the mode of chemical ionization under atmospheric pressure followed by the registration of positive ions corresponding to the protonated forms of the components to be determined. A version of ion chromatography was elaborated for separation. For sample pretreatment, the use of extraction with methanol (for 1-formyl-2,2-dimethylhydrazine) and ultrasonic extraction with a weakly alkaline buffer solution (for other substances) was proposed. [ABSTRACT FROM AUTHOR]

n approach is proposed for the simultaneous determination of formic acid N,N-dimethylhydrazide and 1-methyl-1- H-1,2,4-triazole (ecotoxicants formed upon the oxidative transformation of unsymmetrical dimethylhydrazine) in soils in the concentration range 0.05-50 mg/kg using gas chromatography/mass spectrometry. The conditions for the quantitative extraction of the components by continuous periodic extraction with methanol have been found. The adsorption of formic acid N,N-dimethylhydrazide and 1-methyl-1- H-1,2,4-triazole from solutions by soils of different types has been studied and a method has been proposed for preparing uniform model soil samples with the required contaminant concentrations. [ABSTRACT FROM AUTHOR]