Sorption-chromatographic determination of hydrazine and its substituted derivatives in air

Working conditions were found for the chemisorption preconcentration of hydrazine, phenylhydrazine, and 1,1-dimethylhydrazine from air with tubes containing silica gel with immobilized 4-chloro-5,7-dinitrobenzofurazan and the subsequent determination by high-performance liquid chromatography with diode array detection. A recovery of 98% (hydrazine), 90% (phenylhydrazine), and 97% (1,1-dimethylhydrazine) is attained at a thickness of the sorbent layer of 2 cm, an aspiration rate of 0.2–0.8 L/min, and a volume of aspirated air of 10 L. Silica gel with a particle size of 0.1–0.3 mm impregnated with 4-chloro-5,7-dinitrobenzofurazan (2 wt %) was used as the sorbent. The detection limits of compounds without regard for preconcentration after their desorption are 0.01 (hydrazine), 0.017 (1,1-dimethylhydrazine), and 0.015 mg/m³ (phenylhydrazine).     

The determination of hydrazine and 1,1-dimethylhydrazine,separately or in mixtures,by high-pressure liquid chromatography

A rapid, sensitive liquid chromatographic method for the determination of hydrazine and 1,1-dimethylhydrazine, separately or in mixtures of varying proportions, is described. The procedure involves salicylaldehyde derivative formation followed by chromatography on a reversed phase (octadecylsilane) column with acetonitrile (52%)—0.14 M potassium dihydrogenphosphate (48%) as a mobile phase and u.v. (254 nm) detection. This system is sensitive to 2 μg ml^-1 of hydrazine and 5 μg ml^-1 of 1,1-dimethylhydrazine and has a relative standard deviation of less than 1%. Monomethylhydrazine forms an unstable salicylaldehyde hydrazone; although it cannot be determined, it can be detected (sensitivity 5 μg ml^-1 ) and does not interfere with quantitative measurement of either hydrazine or 1,1-dimethylhydrazine.     

Spectrophotometric determination of hydrazine and 1,1-dimethylhydrazine,separately or in admixture

A rapid, sensitive spectrophotometric method for the determination of hydrazine and 1,1-dimethylhydrazine, separately or in mixtures of varying proportions, is described. The analysis is based on the well-known reaction of these compounds with salicylaldehyde to form, in the case of hydrazine, a symmetrical azine, or with 1,l-dimethylhydrazine, a hydrazone. Absorbance measurements were made in the ultraviolet at wavelengths characteristic of the derivatives and of salicylaldehyde; the results were calculated by means of simultaneous equations. The procedure is sensitive to concentrations of hydrazine as low as 0.3 μg/ml and of 1,1-dimethylhydrazine as low as 0.25 μg/ml. This corresponds to initial sample solutions having a concentration of 3.0 mg of hydrazine and 1.25 mg of 1,1-dimethyl hydrazine per ml.     

Simultaneous Determination of Hydrazine,Methylhydrazine, and 1,1-Dimethylhydrazine by High-Performance Liquid Chromatography with Pre- and Post-Column Derivatization by 5-Nitro-2-Furaldehyde

Approaches to the chromatographic determination of 1,1-dimethylhydrazine and two main products of its degradation (hydrazine and methylhydrazine) on their simultaneous presence are proposed using derivatization by 5-nitro-2-furaldehyde and multi-wavelength spectrophotometric detection of the formed derivatives in the visible spectral region. A combination of preliminary derivatization with separation in the reversed-phase HPLC mode and also ion-chromatographic separation with post-column derivatization allowed us to reach the limits of detection for analytes lower than 1 μg/L and to determine 1,1-dimethylhydrazine at the level of the maximum permissible concentration without preconcentration. The developed approaches were tested on an acid extract of a sample of peat bog soil collected at the place of impact of the first stage of a carrier rocket. The identity of the results obtained by different methods and the high level of soil pollution by hydrazines are shown.     

Organosilyl Isocyanates. Reactions with Hydrazine, 1,1-Dimethylhydrazine,and 1-Methyl-1-[2-(1-Methylhydrazino)ethyl]hydrazine and Structural and Electronic Characteristics

Reactions of organosilyl isocyanates with hydrazine, 1,1-dimethylhydrazine, and 1-methyl-1-[2-(1-methylhydrazino)ethyl]hydrazine provide a facile synthetic route to urea and previously unknown semicarbazides. Quantum chemistry was used to study the structure and electronic properties of (chloromethyl)-dimethylsilyl isocyanate and (chlorodimethylsilyl)methyl isocyanate and to obtain the thermodynamic parameters of their isomerization.     

Spectrophotometric determination of hydrazine,methylhydrazine, and 1,1-dimethylhydrazine with preliminary derivatization by 5-nitro-2-furaldehyde

5-Nitro-2-furaldehyde, a new derivatizing agent for the spectrophotometric determination of hydrazine, methylhydrazine, and 1,1-dimethylhydrazine is proposed. It is characterized by high solubility in water and by a substantial difference in the positions of absorption bands of the formed colored derivatives. The kinetics of the reaction of analyte derivatization is studied, and reaction conditions (pH 5, concentration of derivatizing agent 2 mM, 60° C, duration 40 min) are optimized. The limits of detection are 5, 3, and 1.5 μg/L for hydrazine, methylhydrazine, and 1,1-dimetlhydrazine, respectively. A possibility of the spectrophotometric determination of analytes in their simultaneous presence using the Firordt method is shown. The developed approach is successfully applied to the analysis of polluted peat bog soil selected at a place of impact of the first step of a carrier rocket.     

Simultaneous Determination of Hydrazine,Methylhydrazine and 1,1-Dimethylhydrazine in Waters by HPLC with Spectrophotometric Detection Using Catalysis to Obtain Derivatives

Journal of Analytical Chemistry - A simple, rapid, and sensitive method is developed for the simultaneous determination of hydrazine, methylhydrazine, and 1,1-dimethylhydrazine in waters based on...     

Electrochemical determination of hydrazine and methyl- and 1,1-dimethylhydrazine in air

An electrochemical cell capable of detecting levels of hydrazine, methylhydrazine (MMH) and 1,1-dimethylhydrazine (UDMH) in air is described. It is coupled with a dynamic air-sampling system and electronic control and amplification circuitry to provide a direct-reading portable analyser. The characteristics of this monitoring instrument are discussed. While most of the reported data are specifically for MMH vapour analysis, qualitatively similar results can be obtained when using this instrument for hydrazine or UDMH measurements.     

Anodic oxidation of hydrazine and its methylderivatives on bare Pt and Pt electrode surfaces modified by underpotential metal adsorbates in acetonitrile

The electrooxidation of hydrazine and its methylderivatives (methylhydrazine and 1,1-dimethylhydrazine) on bare Pt and Pt electrode surfaces modified by underpotential metal adsorbates was studied in acetonitrile. On bare Pt, one-third of the molecules of the substances under examination undergo a two-electron oxidation to the corresponding diimides, while the remaining number of molecules act as the required proton acceptors in neutral acetonitrile. In alkaline solutions, hydrazine undergoes a quantitative four-electron oxidation process, while its methyl derivatives are oxidized quantitatively to the corresponding diimides in the same media. The pronounced inhibition effects on hydrazine oxidation caused by underpotential T1 and Pb adsorbates were interpreted in terms of a change in the chemical interaction of hydrazine molecules and the electrode surface modified by the underpotential metal adsorbates.     

Determination of 1,1-Dimethylhydrazine by Reversed-Phase High-Performance Liquid Chromatography with Spectrophotometric Detection as a Derivative with 4-Nitrobenzaldehyde

A procedure was developed for the determination of 1,1-dimethylhydrazine by reversed-phase high-performance liquid chromatography with spectrophotometric detection and preliminary derivatization by the reaction with 4-nitrobenzaldehyde. Conditions were selected for the chromatographic separation and the detection of the peaks of the reagent and 4-nitrobenzaldehyde dimethylhydrazone. The optimum conditions were found for the derivatization of 1,1-dimethylhydrazine with 4-nitrobenzaldehyde. The determination limit of 1,1-dimethylhydrazine in aqueous solutions was 120 g/L (2 M/L).     

Temporary inactivation of plasma amine oxidase by alkylhydrazines. A combined enzyme/model study implicates cofactor reduction/reoxidation but cofactor deoxygenation and subsequent reoxygenation in the case of hydrazine itself

It has been known for some time that hydrazine and its methyl and 1,1-dimethyl analogues induce inactivation of the copper-containing quinone-dependent plasma amine oxidase but that the activity recovers over time, suggesting metabolism of all three inhibitors. However, the mechanism responsible for loss and regain of activity has not been investigated. In this study a combination of enzyme studies under a controlled atmosphere along with model studies using 5-tert-butyl-2-hydroxy-1,4-benzoquinone to mimic the 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor of the enzyme suggest that regain of enzyme activity represents two different O(2)-dependent processes. In the case of methylhydrazine and 1,1-dimethylhydrazine, we propose that the inactive methylhydrazone/azo form of the enzyme slowly rehydrates and eliminates MeN=NH to give the triol cofactor form, which instantly reoxidizes to the catalytically active quinone form in the presence of O(2). Metabolism of methylhydrazine represents its conversion to CH(4) and N(2), and of 1,1-dimethylhydrazine to CH(2)=O, CH(4), and N(2). In the case of hydrazine itself, however, we propose that the inactive hydrazone/azo form of the enzyme instead undergoes a slow decomposition, probably facilitated by the active-site copper, to give N(2) and a novel 5-desoxy resorcinol form of the cofactor. The latter undergoes a rapid, but noninstantaneous reoxygenation at C5 to restore the active cofactor form, also probably mediated by the active-site copper.     

Trifluoromethanesulfonic Hydrazides

We succeeded to observe at low temperature in reactions of trifluoromethanesulfonic anhydride and trifluoromethanesulfonyl chloride with hydrazine, phenyl hydrazine, and 1,1-dimethylhydrazine a formation of the corresponding trifluoromethanesulfonic hydrazides that at heating to room temperature decomposed liberating nitrogen and affording trifluoromethanesulfinic acid. 2-Phenyl-2H-1,2,3-triazole-4-carboxylic hydrazide reacted with trifluoromethanesulfonic anhydride to furnish trifluoro-N'-(2-phenyl-2H-1,2,3-triazol-4-ylcarbonyl)methane-sulfonic hydrazide that decomposed at heating with elimination of trifluoromethanesulfinic acid and nitrogen yielding 2-phenyl-2H-1,2,3-triazole-4-carbaldehyde.     

Synthesis of hydrogenated heterocyclic compounds from α-methylene-1,5-diketones. 5. Synthesis and stereochemistry of the products of addition of hydrazines to 2,4-dibenzoyl-3-phenyl-1,4-pentadiene

The addition of phenyl- and 1,1-dimethylhydrazine to 2,4-dibenzoyl-3-phenyl-l,4-pentadiene leads to the formation of the corresponding 1-substituted 3,5-di-benzoyl-4-phenylpiperidines. 3-Benzoyl-4,6-diphenyl-1,7-diazabicyclo[3.2.1]oct-6-ene was obtained in the reaction with hydrazine.See [1] for Communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 789–791, June, 1981.     

A sensitive chromatographic determination of hydrazines by naphthalene-2,3-dialdehyde derivatization

A new high-performance liquid chromatography (HPLC) method for the sensitive simultaneous determination of hydrazine (Hy), monomethylhydrazine (MMH) and 1,1-dimethylhydrazine (UDMH) based upon the derivatization of hydrazines with naphthalene-2,3-dialdehyde and the separation of the derivatives on Zorbax Eclipse AAA column in a single chromatographic run under acidic conditions (pH 2.4) was developed. Hydrazine and monomethylhydrazine derivatives were found to be strongly fluorescent at λ_ex?=?273?nm, λ_em?=?500?nm. It was shown that UDMH derivative can be detected as non-fluorescent hydrazone at 290?nm by UV-detection. Limits of detection were 0.05?µg?·?L^?1 for Hy and MMH, and 1?µg?·?L^?1 for UDMH for the injection volume of 100?µL. The method was validated for water sample analysis. It proved to be selective, accurate and precise with the supplementary advantage of the simple and rapid sample preparation.     

Chromogenic Reaction of 1,1-Dimethylhydrazine with Aryltetrazolium Salts

The reactions of 1,1-dimethylhydrazine with 2,3,5-triphenyl-2Н-tetrazolium and 2,5-diphenyl-3-(4-nitrophenyl)-2Н-tetrazolium chlorides in a solution and on a cellulose carrier have been studied by means of spectrophotometry and chromato–mass spectrometry to develop new chromogenic indicators for detection of 1,1-dimethylhydrazine. 1,3,5-Triphenylformazan and 1,3-diphenyl-5-(4-nitrophenyl)formazan are formed in these reactions, respectively; deep red shifts have been observed. Other products of these reactions result from oligomerization and addition of short-living 1,1-dimethylhydrazyl and tetrazolium radicals.     

Hydrophilic interaction liquid chromatography with alcohol as a weak eluent

There has been a significant increase of interest in polar compound separation by hydrophilic interaction liquid chromatography (HILIC), in which acetonitrile is mostly used as a weak eluent. Although replacing acetonitrile with alcohols as organic modifiers has been previously reported, the separation mechanism was poorly understood. In this paper we explored the separation mechanism through the method development for the analysis of the trace amounts of polar and basic hydrazines, which were genotoxic in nature. Separation parameters such as the type and concentration of alcohol, acid modifier, and buffer in mobile phase as well as the choice of stationary phase and column temperature were studied. The data indicated that both electrostatic and hydrophilic interactions contributed to the retention and separation of the hydrazines. The results presented here provide insight into the adjustment of the retention and separation of analytes in HILIC mode with alcohol as a weak eluent. The optimized HILIC method coupled with chemiluminescent nitrogen detection (CLND) is simple and sensitive (reporting limit at 0.02%) and was applied to simultaneous analysis of hydrazine and 1,1-dimethylhydrazine in a pharmaceutical intermediate.     

Direct determination of hydrazine,methylhydrazine, and 1,1-dimethylhydrazine by zwitterionic hydrophilic interaction liquid chromatography with amperometric detection

A promising alternative to ion-chromatographic methods currently used for the direct determination of hydrazines is provided by hydrophilic interaction liquid chromatography (HILIC). In this work, we propose a method for the simultaneous determination of hydrazine, methylhydrazine and 1,1-dimethylhydrazine in natural waters and soils based on a combination of chromatographic separation on a zwitterionic sulfobetaine stationary phase (Nucleodur HILIC) in the HILIC mode with amperometric detection.

Effects of different factors on the retention of analytes were studied and the optimum conditions of analysis were found. We recommend a mixture of acetonitrile with an aqueous phosphate buffer solution of pH 2.5 (78:22 v/v) with an ionic strength of 20 mM as a mobile phase. Detection in the direct current mode was performed at a working electrode potential of 1.1 V.

The advantages of the method are the high efficiency of separation, rapidity, high sensitivity and a wide dynamic range of analyte concentrations, covering four orders of magnitude. The attained LOD values for analytes lie in the range 0.07–0.13 μg L^–1, which is two orders of magnitude lower than those in currently used methods of ion chromatography with electrochemical and mass spectrometric detection.

The method was validated on samples of natural waters of different origin using the added–found technique. It was found that the error of analysis did not exceed 10% for river and ground waters and increased to 20–30% for peat bog surface waters.

The possibility of application of the developed method to the analysis of soils was shown on samples of peat bog soils selected at places of impact of the first steps of carrier rockets and polluted by rocket fuel based on 1,1-dimethylhydrazine.     

Determination of hydrazines by chip electrophoresis with contactless conductivity detection

In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.     

Threshold-photoelectron spectroscopic study of methyl-substituted hydrazine compounds

The valence shell electronic structures of methylhydrazine (CH(3)NHNH(2)), 1,1-dimethylhydrazine ((CH(3))(2)NNH(2)) and tetramethylhydrazine ((CH(3))(4)N(2)) have been studied by recording threshold and conventional (kinetic energy resolved) photoelectron spectra. Ab initio calculations have been performed on ammonia and the three methyl substituted hydrazines, with the structures being optimized at the B3-LYP/6-31+G(d) level of theory. The ionization energies of the valence molecular orbitals were calculated using the Green's function method, allowing the photoelectron bands to be assigned to specific molecular orbitals. The ground-state adiabatic and vertical ionization energies, as determined from the threshold photoelectron spectra, were IE(a) = 8.02 +/- 0.16 eV and IE(v) = 9.36 +/- 0.02 eV for methylhydrazine, IE(a) = 7.78 +/- 0.16 eV and IE(v) = 8.86 +/- 0.01 eV for 1,1-dimethylhydrazine and IE(a) = 7.26 +/- 0.16 eV and IE(v) = 8.38 +/- 0.01 eV for tetramethylhydrazine. Due to the large geometry change that occurs upon ionization, these IE(a) values are all higher than the true thresholds. New features have been observed in the inner valence region and these have been compared with similar structure in the spectrum of hydrazine. The effect of resonant autoionization on the threshold photoelectron yield is discussed. New heats of formation (Delta(f)H) are proposed for the three hydrazines on the basis of G3 calculations: 107, 94, and 95 kJ/mol for methylhydrazine, 1,1-dimethyhydrazine and tetramethylhydrazine, respectively. The previously reported Delta(f)H for tetramethylhydrazine is shown to be erroneous.     

Nucleophilic Substitution of Chlorine with Hydrazine,Methylhydrazine, and 1,1-Dimethylhydrazine in 5-Aryl-2-chloromethyl-1,3,4-oxadiazoles

The reactions of 1,1-dimethylhydrazine, methylhydrazine, and hydrazine hydrate with 5-aryl-2-chloromethyl-1,3,4-oxadiazoles were studied. The structures and compositions of the final products were confirmed by ¹H NMR spectroscopy and elemental analysis.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 470–473.Original Russian Text Copyright © 2005 by Baranov, Tsypin, Malin, Laskin.