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.

Quantification of trace transformation products of rocket fuel unsymmetrical dimethylhydrazine in sand using vacuum-assisted headspace solid-phase microextraction.

Quantification of unsymmetrical dimethylhydrazine transformation products in solid samples is an important stage in monitoring of environmental pollution caused by heavy rockets launches. The new method for simultaneous quantification of unsymmetrical dimethylhydrazine transformation products in sand samples using vacuum-assisted headspace solid-phase microextraction without addition of water followed by gas chromatography-mass spectrometry is proposed. Decreasing air evacuation time from 120 to 20 s at 23 °C resulted in increased responses of analytes by 25-46% and allowed obtaining similar responses as after evacuation at -30 °C. The best combination of responses of analytes and their relative standard deviations (RSDs) was achieved after air evacuation of a sample (m = 1.00 g) for 20 s at 23 °C, incubation for 30 min at 40 °C, and 30-min extraction at 40 °C by Carboxen/polydimethylsiloxane (Car/PDMS) fiber. The method was validated in terms of linearity (R2=0.9912-0.9938), limits of detection (0.035 to 3.6 ng g-1), limits of quantification (0.12-12 ng g-1), recovery (84-97% with RSDs 1-11%), repeatability (RSDs 3-9%), and reproducibility (RSDs 7-11%). It has a number of major advantages over existing methods based on headspace solid-phase microextraction-lower detection limits, better accuracy and precision at similar or lower cost of sample preparation. The developed method was successfully applied for studying losses of analytes from open vials with model sand spiked with unsymmetrical dimethylhydrazine transformation products. It can be recommended for analysis of trace concentrations of unsymmetrical dimethylhydrazine transformation products when studying their transformation, migration and distribution in contaminated sand.

Effects of oxidant and catalyst on the transformation products of rocket fuel 1,1-dimethylhydrazine in water and soil.

Existing methods for cleanup of wastewaters and soils polluted with the extremely toxic rocket fuel unsymmetrical dimethylhydrazine (UDMH) are mainly based on the treatment with various oxidative reagents. Until now, the assessment of their effectiveness was based on the residual content of UDMH and did not take into account the possibility of the formation of a large number of potentially dangerous nitrogen-containing transformation products (TPs). In this study, using the recently developed approach based on high-resolution Orbitrap mass spectrometry, the comprehensive characterization of UDMH TPs formed by the action of air oxygen and different oxidants (Fenton's reagent, KMnO4, HOCl, H2O2 in the presence of Cu2+ and [Fe (EDTA)]- catalysts) typically used to detoxify spill sites was performed. The range of the identified molecular formulas of TPs comprised 303 compounds of various classes. Among them, there is a number of major products not previously described in the literature. It was established that none of the investigated oxidative reagents ensures complete conversion of rocket fuel to safe compounds. The hydrogen peroxide based reagents, particularly H2O2 + Na [Fe (EDTA)] system currently used in Kazakhstan, give the greatest number of TPs, for many of which a toxicity was not characterized so far. The majority of the compounds found in model solutions was detected in extracts of soil from the crash site of the Proton carrier rocket, which was subjected to the on-site reagent treatment. During successive treatments, along with the decrease in the number of detectable UDMH TPs, their ratios change in favor of amines.

Evaluation of a novel hollow fiber membrane technique for collection of 1,1-dimethylhydrazine in air.

The purpose of this study was to develop a novel one-step method for the time-weighted average determination of 1,1-dimethylhydrazine (UDMH) in the air followed by spectrophotometric detection. For this reason, 0.1% hydrochloric acid as the absorbent was used in hollow fiber (HF) membrane for sampling of UDMH from an atmospheric standard chamber. Response surface methodology (RSM) with central composite design (CCD) was used to optimize the sampling parameters, such as flow rate and sampling time. Moreover, several analytical parameters including breakthrough (BT) volume, storage time, and carryover effect of the proposed HF were investigated. The results showed that optimal sampling rate was 9.90 mL/min. In order to validate the proposed method, it was compared with the National Institute for Occupational Safety and Health (NIOSH) 3515 method, which showed good compatibility between the two methods. Intra- and inter-day repeatability values of the HF method were in the range 0.082-0.1 and 0.091-0.12, respectively, and the limits of detection (LODs) and limits of quantitation (LOQs) were 0.002 and 0.006 ng/mL, respectively. The storage time of the proposed HF was 7 days at 2 °C. These results demonstrated that the one-step HF membrane offered a high sensitivity for sampling of UDMH in air.

Determination of transformation products of unsymmetrical dimethylhydrazine in water using vacuum-assisted headspace solid-phase microextraction.

A new, sensitive and simple method based on vacuum-assisted headspace solid-phase microextraction (Vac-HSSPME) followed by gas chromatography-mass-spectrometry (GC-MS), is proposed for the quantification of rocket fuel unsymmetrical dimethylhydrazine (UDMH) transformation products in water samples. The target transformation products were: pyrazine, 1-methyl-1H-pyrazole, N-nitrosodimethylamine, N,N-dimethylformamide, 1-methyl-1Н-1,2,4-triazole, 1-methyl-imidazole and 1H-pyrazole. For these analytes and within shorter sampling times, Vac-HSSPME yielded detection limits (0.5-100 ng L-1) 3-10 times lower than those reported for regular HSSPME. Vac-HSSPME sampling for 30 min at 50 °C yielded the best combination of analyte responses and their standard deviations (<15%). 1-Formyl-2,2-dimethylhydrazine and formamide were discarded because of the poor precision and accuracy when using Vac-HSSPME. The recoveries for the rest of the analytes ranged between 80 and 119%. The modified Mininert valve and Thermogreen septum could be used for automated extraction as it ensured stable analyte signals even after long waiting times (>24 h). Finally, multiple Vac-HSSME proved to be an efficient tool for controlling the matrix effect and quantifying UDMH transformation products.

Characterisation of oxidation products of 1,1-dimethylhydrazine by high-resolution orbitrap mass spectrometry.

1,1-Dimethylhydrazine is used as a fuel for carrier rockets in the majority of countries implementing space exploration programs. Being highly reactive, 1,1-dimethylhydrazine easily undergoes oxidative transformation with the formation of a number of toxic, mutagenic, and teratogenic compounds. The use of high-resolution mass spectrometry for the study of the reaction of 1,1-dimethylhydrazine oxidation with hydrogen peroxide in aqueous solution allowed us to find hundreds of nitrogen-containing products of the CHN and CHNO classes, formed via radical processes. The vast majority of the compounds have not been previously considered as possible products of the transformation of rocket fuel. We have shown that the oxidation of 1,1-dimethylhydrazine proceeds in two stages, with the formation of a great number of complex unstable intermediates that contain up to ten nitrogen atoms. These intermediates are subsequently converted into final reaction products with a concomitant decrease in the average molecular weight. The intermediates and final products of the oxidative transformation of 1,1-dimethylhydrazine were characterised on the basis of their elemental composition using van Krevelen diagrams and possible compounds corresponding to the most intense peaks in the mass spectra were proposed. The data obtained are indicative of the presence of the following classes of heterocyclic nitrogen-containing compounds among the oxidation products: imines, piperidines, pyrrolidines, dihydropyrazoles, dihydroimidazoles, triazoles, aminotriazines, and tetrazines. The results obtained open up possibilities for the targeted search and identification of new toxic products of the degradation of rocket fuel and, as a result, a more adequate assessment of the ecological consequences of space-rocket activity.

Role of Chlorine Dioxide in N-Nitrosodimethylamine Formation from Oxidation of Model Amines.

N-Nitrosodimethylamine (NDMA) is an emerging disinfection byproduct, and we show that use of chlorine dioxide (ClO2) has the potential to increase NDMA formation in waters containing precursors with hydrazine moieties. NDMA formation was measured after oxidation of 13 amines by monochloramine and ClO2 and pretreatment with ClO2 followed by postmonochloramination. Daminozide, a plant growth regulator, was found to yield 5.01 ± 0.96% NDMA upon reaction with ClO2, although no NDMA was recorded during chloramination. The reaction rate was estimated to be ∼0.0085 s(-1), and on the basis of our identification by mass spectrometry of the intermediates, the reaction likely proceeds via the hydrolytic release of unsymmetrical dimethylhydrazine (UDMH), with the hydrazine structure a key intermediate in NDMA formation. The presence of UDMH was confirmed by gas chromatography-mass spectrometry analysis. For 10 of the 13 compounds, ClO2 preoxidation reduced NDMA yields compared with monochloramination alone, which is explained by our measured release of dimethylamine. This work shows potential preoxidation strategies to control NDMA formation may not impact all organic precursors uniformly, so differences might be source specific depending upon the occurrence of different precursors in source waters. For example, daminozide is a plant regulator, so drinking water that is heavily influenced by upstream agricultural runoff could be at risk.

[REAL AND UNREAL BACKLASHES OF AEROSPACE ACTIVITY FOR THE HEALTH OF POPULATION RESIDING NEAR AREAS OF FALL OF BEING SEPARATED PARTS OF CARRIER ROCKETS].

Since the late 1990s, the ongoing debate about the consequences of the rocket-space activities for the health of people residing near areas offall ofseparatingfrom parts of rockets. Some scientists (Kolyado IB et al., 2001, 2013; Shoikhet YN et al., 2005, 2008; Skrebtsova NV 2005, 2006, Sidorov PI et al., 2007) argue that the main cause of morbidity is the effect of unsymmetrical dimethyl hydrazine (UDMH). However, environmentalists find it only in areas offalling fragments of separated parts of carrier rockets. Presented in the article data were obtained as a result of perennial epidemiological and hygienic research. There was performed a hygienic assessment of the content of chemical substances in water soil andfood, nutritional status and health risk near areas of the district of falling 310 and 326. There were studied conditions of work and the health of military personnel at the sites of storage of propellant components. The relationship between revealed diseases and UDMH was not established, but there was their causality due to the influence of environmental factors characteristic of territories and living conditions. In the settlements near the area of falling district 310 the share of extremely anxious persons was shown to be 1.8 times higher than in controls, which is caused by cases of falling fragments stages of carrier rockets in the territory of settlements.

Transformation products of 1,1-dimethylhydrazine and their distribution in soils of fall places of rocket carriers in Central Kazakhstan.

In our research, three fall places of first stages of Proton rockets have been studied for the presence and distribution of transformation products of 1,1-dimethylhydrazine (1,1-DMH). Results of identification of transformation products of 1,1-DMH in real soil samples polluted due to rocket fuel spills allowed to detect 18 earlier unknown metabolites of 1,1-DMH being formed only under field conditions. According to the results of quantitative analyses, maximum concentrations of 1-methyl-1H-1,2,4-triazole made up 57.3, 44.9 and 13.3 mg kg(-1), of 1-ethyl-1H-1,2,4-triazole - 5.45, 3.66 and 0.66 mg kg(-1), of 1,3-dimethyl-1H-1,2,4-triazole - 24.0, 17.8 and 4.9 mg kg(-1) in fall places 1, 2 and 3, respectively. 4-Methyl-4H-1,2,4-triazole was detected only in fall places 2 and 3 where its maximum concentrations made up 4.2 and 0.66 mg kg(-1), respectively. The pollution of soils with transformation products of 1,1-DMH was only detected in epicenters of fall places having a diameter of 8 to10 m where rocket boosters landed. The results of a detailed study of distribution of 1,1-DMH transformation products along the soil profile indicate that transformation products can migrate down to the depth of 120 cm, The highest concentrations of 1,1-DMH transformation products were detected, as a rule, at the depth 20 to 60 cm. However, this index can vary depending on the compound, humidity and physical properties of soil, landscape features and other conditions. In the surface layer, as a rule, only semi-volatile products of transformation were detected which was caused by fast evaporation and biodegradation of volatile metabolites.

[Results of study concerning possible influence of rocket space activities on public health].

Using special medical examination results and specified criteria of objective evaluation, the authors summarized results of studies concerning health state of population dwelling in area possibly influenced by rocket space activities factors.

Screening of transformation products in soils contaminated with unsymmetrical dimethylhydrazine using headspace SPME and GC-MS.

The paper describes a novel SPME-based approach for sampling and analysis of transformation products of highly reactive and toxic unsymmetrical dimethylhydrazine (UDMH) which is used as a fuel in many Russian, European, Indian, and Chinese heavy cargo carrier rockets. The effects of several parameters were studied to optimize analyte recovery. It was found that the 85 microm Carboxen/polydimethylsiloxane fiber coating provides the highest selectivity for selected UDMH transformation products. Optimal sampling/sample preparation parameters were determined to be 1-h soil headspace sampling time at 40 degrees C. The GC inlet temperature was optimized to 170 degrees C held for 0.1 min, then 1 degrees C s(-1) ramp to 250 degrees C where it was held for 40 min. Temperature programming resulted in a fast desorption along with minimal chemical transformation in the GC inlet. SPME was very effective extracting UDMH transformation products from soil samples contaminated with rocket fuel. The use of SPME resulted in high sensitivity, speed, small labor consumption due to an automation and simplicity of use. It was shown that water addition to soil leads to a significant decrease of recovery of almost all target transformation products of UDMH. The use of SPME for sampling and sample preparation resulted in detection of the total of 21 new compounds that are relevant to the UDMH transformation in soils. In addition, the number of confirmed transformation products of UDMH increased from 15 to 27. This sampling/sample preparation approach can be recommended for environmental assessment of soil samples from areas affected by space rocket activity.

Determination of hydrazine, monomethylhydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine by nonaqueous capillary electrophoresis with amperometric detection.

The present study is concerned with the application of nonaqueous capillary electrophoresis (NACE) with electrochemical detection (ED) to the separation and quantitative determination of hydrazine (Hy) and its methyl derivatives. The best performance of NACE-ED was found when using 4 mM sodium acetate/10 mM acetic acid/methanol: acetonitrile = 1:2 as the running buffer, with a bare platinum working electrode set at +1.0 V in an end-column amperometric detection cell. The choice and ratio of suitable solvents for the separation and injection media played an essential role for the performance characteristics of the method. The limits of detection for Hy, methylhydrazine, symmetrical dimethylhydrazine, and unsymmetrical dimethylhydrazine were 5, 2, 12, and 1 ng/mL, respectively. This is between one and two orders of magnitude lower than that achieved by previously reported CE-ED methods in aqueous buffer systems in conjunction with various types of chemically modified electrodes. The practical utility of the new NACE-ED methodology is demonstrated in terms of the determination of traces of Hys in spiked environmental samples containing a wide range of explosives and related compounds.

Analysis of cigarette mainstream smoke for 1,1-dimethylhydrazine and vinyl acetate by gas chromatography-mass spectrometry.

1,1-Dimethylhydrazine, also known as unsymdimethylhydrazine (UDMH) and vinyl acetate (VA), are both classified by the International Agency for Research on Cancer as 2B carcinogens (possibly carcinogenic to humans) and listed as cigarette smoke constituents; however, there is little or no quantitative data available on them. For UDMH in cigarette smoke, neither a yield nor a method has been published. For VA, the most recent information on yields dates back to 1965. To bridge this gap, we have developed new gas chromatographic-mass spectrometric methods for both compounds to determine their yields in cigarette smoke. UDMH is determined by derivatization with 2-nitrobenzaldehyde in methanol and is not found in cigarette smoke at levels above the detection limit of 19 ng/cig. In further experiments, when UDMH is added to the smoke stream or air stream of lit or unlit cigarettes, the derivative 2-nitrobenzaldehyde-2,2-dimethylhydrazone is found only in the air stream of the unlit cigarettes. From this, we conclude that UDMH is either not formed during smoking at all or, if it is, it reacts immediately and quantitatively with other smoke constituents (e.g., aldehydes) and is therefore not detectable in cigarette smoke. VA is determined by trapping in acetone at -78 degrees C and is found at a concentration of 270 ng/cig for a standard reference cigarette with a cellulose acetate filter (the reference cigarette 1 R4F). In the literature, VA is reported at concentrations of 1.6 microg/cig for a cigarette with a cellulose acetate/charcoal filter and 4 microg/cig for a cigarette with a cellulose acetate filter and for an unfiltered cigarette.

Luminescence and ESR studies of relationships between O(-)-centres and structural iron in natural and synthetically hydrated kaolinites.

Luminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between hydration-induced luminescence and g = 2 ESR signals associated with O(-)-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 angstroms synthetically hydrated, kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O(-)-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 angstroms hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O(-)-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 angstroms hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.

New method for the determination of 1,1-dimethylhydrazine residues in apples and peaches.

A new method for determining 1,1-dimethylhydrazine (UDMH) in peaches and apples is presented. The method consists of extraction with L-ascorbic acid, derivatization with 2-nitrobenzaldehyde to the corresponding hydrazone, and cleanup on an alumina column. The hydrazone derivative is determined by gas chromatography using an electron-capture detector. Recoveries were determined from 10 to 100 ppb. Stability of the UDMH residues on frozen peaches was investigated, and results indicate that the residues degrade even while frozen.