Investigation on the compositions of unsymmetrical dimethylhydrazine treatment with different oxidants using solid-phase micro-extraction-gas chromatography-mass spectrometer

Intelligent Workflow and Software for Non-Target Analysis of Complex Samples Using a Mixture of Toxic Transformation Products of Unsymmetrical Dimethylhydrazine as an Example

Unsymmetrical dimethylhydrazine (UDMH) is a widely used rocket propellant. Entering the environment or being stored in uncontrolled conditions, UDMH easily forms an enormous variety (at least many dozens) of transformation products. Environmental pollution by UDMH and its transformation products is a major problem in many countries and across the Arctic region. Unfortunately, previous works often use only electron ionization mass spectrometry with a library search, or they consider only the molecular formula to propose the structures of new products. This is quite an unreliable approach. It was demonstrated that a newly proposed artificial intelligence-based workflow allows for the proposal of structures of UDMH transformation products with a greater degree of certainty. The presented free and open-source software with a convenient graphical user interface facilitates the non-target analysis of industrial samples. It has bundled machine learning models for the prediction of retention indices and mass spectra. A critical analysis of whether a combination of several methods of chromatography and mass spectrometry allows us to elucidate the structure of an unknown UDMH transformation product was provided. It was demonstrated that the use of gas chromatographic retention indices for two stationary phases (polar and non-polar) allows for the rejection of false candidates in many cases when only one retention index is not enough. The structures of five previously unknown UDMH transformation products were proposed, and four previously proposed structures were refined.

Preparation and characterization of graphene oxide/O-carboxymethyl chitosan (GO/CMC) composite and its unsymmetrical dimethylhydrazine (UDMH) adsorption performance from wastewater

The removal of unsymmetrical dimethylhydrazine (UDMH) has long been a concern because of its harmful effect on the environment and humans. This study aimed to prepare a novel graphene oxide/O-carboxymethyl chitosan (GO/CMC) composite adsorbent using the solution-blending method for the removal of UDMH from wastewater. The prepared GO/CMC was systematically characterized by Fourier-transform infrared, Raman, scanning electronic microscopy, transmission electron microscopy, thermogravimetric, and zeta potential analyses. The effects of initial pH, temperature, adsorbent dosage, initial concentration, contact time, and recyclability on the UDMH adsorption behaviour of GO/CMC were studied. The adsorption kinetics was consistent with the pseudo-second-order kinetics model, and the adsorption process was mainly controlled by chemisorption. Adsorption isotherms indicated that the adsorption of UDMH by GO/CMC followed the Langmuir adsorption isotherm. The adsorption mechanisms were mainly electrostatic attraction, hydrogen bonding, and surface complexation. Furthermore, GO/CMC composites can be used as a renewable and eco-friendly adsorbent for the removal of UDMH wastewater. The designed GO/CMC composites exhibited a relatively satisfactory recyclability and removal efficiency after five adsorption-desorption cycles.

Review on the environmental impact of emissions from space launches: a case study for areas affected by the Russian space programme

In this paper, we summarised the main field-based approaches and a large volume of data on the territories affected by the Russian space programme conducted at Plesetsk, Baikonur, and Vostochny cosmodromes. Influence of space transportation on the ozone layer depletion, as well as on environmental and human health, is negligible. The environmental consequences of rocket and space activities within launch pads and the terrestrial drop zones of jettisoned first stages of launch vehicles are allowable. Moreover, it is negligible in the second stage drop zones. Unsymmetrical dimethylhydrazine pollution is local and does not result in the formation of ecological disaster zones because ecosystems restore by themselves. Influence of rocket launches on the mesospheric cloud formation is short-time or/and insignificant. The environmental impact of space transportation by the Russian space programme on the terrestrial ecosystems is well-studied. To approve or to disprove these findings similar researches should be carried out in other terrestrial and aquatic drop zones affected due to the space programmes of other countries.

Rapid Simultaneous Quantification of 1-Formyl-2,2-Dimethylhydrazine and Dimethylurea Isomers in Environmental Samples by Supercritical Fluid Chromatography-Tandem Mass Spectrometry

When released to the environment, the rocket fuel unsymmetrical dimethylhydrazine (UDMH) undergoes oxidative transformations, resulting in the formation of an extremely large number of nitrogen-containing transformation products, including isomeric compounds which are difficult to discriminate by common chromatography techniques. In the present work, supercritical fluid chromatography–tandem mass spectrometry (SFC-MS/MS) was proposed for resolving the problem of fast separation and simultaneous quantification of 1-formyl-2,2-dimethylhydrazine (FADMH) as one of the major UDMH transformation products, and its isomers—1,1-dimethylurea (UDMU) and 1,2-dimethylurea (SDMU). 2-Ethylpyridine stationary phase provided baseline separation of analytes in 1.5 min without the distortion of the chromatographic peaks. Optimization of SFC separation and MS/MS detection conditions allowed for the development of rapid, sensitive, and “green” method for the simultaneous determination of FADMH, UDMU, and SDMU in environmental samples with LOQs of 1–10 µg L⁻¹ and linear range covering three orders of magnitude. The method was validated and successfully tested on the real extracts of peaty and sandy soils polluted with rocket fuel and UDMH oxidation products. It was shown that both UDMU and SDMU are formed in noticeable amounts during UDMH oxidation. Despite relatively low toxicity, UDMU can be considered one of the major UDMH transformation products and a potential marker of soil pollution with toxic rocket fuel.

Unsymmetrical dimethylhydrazine and related compounds in the environment: Recent updates on pretreatment, analysis, and removal techniques

Unsymmetrical dimethylhydrazine (1,1-Dimethylhydrazine, UDMH) has been widely used as aerospace fuel in many countries. The launch of space vehicles can cause the release and leakage of UDMH into the environment, posing serious threats to ecology system and human population. Even worse, the health risks are also pertinent to its numerous classes of transformation products including N-Nitrosodimethylamine (NDMA), because most of them display carcinogenic and mutagenic properties. Recently, there has been an intense ongoing development of simple, fast, green, and effective techniques for determining and removing these hazardous substances. This review summarizes the latest research progress regarding the sources, fates, pretreatment, analysis, and removal techniques of UDMH and related products in the environment. Sample preparation methods mainly include pressurized liquid extraction, liquid-phase microextraction techniques, solid-phase extraction, headspace-solid-phase microextraction, and supercritical fluid extraction. Detection and identification methods mainly include high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), gas chromatography coupled with tandem mass spectrometry (GC-MS/MS), and sensors. Removal methods mainly include advanced oxidation processes, adsorption, biodegradation techniques. The advantages/disadvantages, applications, and trends of the proposed approaches are thoroughly discussed to provide a valuable reference for further studies.

Validation of the promotion mechanism between bromide and UDMH to form NDMA during ozonation

Unsymmetrical dimethylhydrazine (UDMH) is found to generate substantial carcinogenic nitroso-dimethylamine (NDMA) during ozonation, moreover, its formation is promoted by ubiquitous bromide ions (Br^-) in water matrixes, but the mechanism is still unclear. In this study, effects of Br^- on NDMA formation during ozonation of UDMH were studied, meanwhile, its promotion pathways were also determined. The results demonstrated that Br^- promoted NDMA formation from UDMH during ozonation, the formation rate constant with Br^- is over 7 times of that without Br^-. NDMA amount raised from 142.5 to 327.5 μg/L when Br^- dosages increased from 0 to 100 μM. No matter with or without Br^-, the augment of O₃ dosages facilitated NDMA formation; the maximum value was achieved at pH 8. NDMA decreased dramatically from 173.8 to 123.5 μg/L with HCO₃^- raising from 0 to 160 μM, while increasing remarkably to 222.5 μg/L with SO₄^2- dosing. In addition, NOM inhibited NDMA formation from UDMH during ozonation. The mass spectrum of LC-MS/MS verified that the generation of Br-UDMH was main cause for promoting NDMA formation. Moreover, hypobromous acid (HBrO) was confirmed to be responsible for Br-UDMH formation. In addition, the position that oxidants and Br^- attacked was demonstrated based on Gaussian calculation. The results of this study could provide theoretical basis for the application of ozonation in bromine-containing water matrixes.

Ecological consequences of space rocket accidents in Kazakhstan between 1999 and 2018

In this paper, we briefly described the ecological consequences of six space rocket accidents launched from the Baikonur Cosmodrome between 1999 and 2018 and focused on an assessment of efficiency of soil remediation following the accidental crash of launch vehicle Proton-M on July 2, 2013, which resulted in the severest environmental impact in the modern Russian space industry. On the day after the accident, the content of carcinogenic unsymmetrical dimethylhydrazine and nitrosodimethylamine, as well as nitrate in soils of the crash site exceeded their maximal permissible concentrations by 8900, 6100 and 85 times, respectively. Mitigation measures included soil detoxication by a solution of 10% H₂O₂ and 1% iron complexonate, soil excavation and ploughing. Two years later (in April 2015), both unsymmetrical dimethylhydrazine and nitrosodimethylamine concentrations were below 0.05 mg/kg and nitrate concentration did not exceed 3.9 g/kg. As compared to background sites, soils of the crash site had significantly (P-value<0.05) lower values of pH and the content of total organic carbon, basicity from soda and carbonates and higher total nitrogen and soluble salt contents. Soil microbial communities were the most vulnerable component of the disturbed arid ecosystems, as their suppressed condition was indicated by a low biochemical oxygen demand and a very low cellulase activity.

Migration and transformation of 1,1-dimethylhydrazine in peat bog soil of rocket stage fall site in Russian North

An ingress of highly toxic rocket fuel 1,1-dimethylhydrazine (UDMH) and its transformation products into environment represents a serious negative impact on the ecosystem, as well as human health. The present research demonstrates the first data on the spatial distribution and quantification of UDMH and its main transformation products (methylhydrazine, hydrazine, 1,1,4,4-tetramethyltetrazene, formaldehyde, acetaldehyde and furaldehyde N,N-dimethylhydrazones, 1-formyl-2,2-dimethylhydrazine, N,N-dimethylformamide, N-nitrosodimethylamine, and 1-methyl-1H-1,2,4-triazole) in the peat bog soil of the fall site in subarctic region. One hundred samples of peat bog soil and one sample of surface water were analyzed by the developed earlier methodology. The considerable amounts of UDMH and most of its transformation products were found at distances of not >10 m from the center of the fall site. The maximum concentration of UDMH was found near the center, where maximal permissible concentration (MPC) was exceeded 2400-fold. The greatest pollution was observed in the surface soil layer, while methylhydrazine, 1-methyl-1H-1,2,4-triazole, 1-formyl-2,2-dimethylhydrazine, formaldehyde and acetaldehyde N,N-dimethylhydrazones, and N,N-dimethylformamide were the major UDMH transformation products. With increasing distance from the center, the composition of the transformation products changes in favor of the last three compounds. Formaldehyde N,N-dimethylhydrazone and N,N-dimethylformamide are present in all soil samples and can be considered as reliable markers of contamination with rocket fuel. The surface water of the peat bog contained four UDMH transformation products in considerable concentrations, including extremely toxic N-nitrosodimethylamine. The processes of migration and transformation of UDMH in peat bog soil differ considerably from those in sandy soils. This is due to cold climate of subarctic zone, the reducing environment of peat bog, and strong binding of hydrazines to organic matter of peat, which prevents migration of pollutants and contributes to the long-term maintenance of high levels of soil pollution.