Control over phase transformations in the crystal lattice of ammonium nitrate by modification of the system of intermolecular interactions via addition of organic substances

Methods for phase stabilization of ammonium nitrate were sought for to substantially extend the application fields of this oxidizing agent in self-combustible formulations for various purposes, including the new generation of gas-generating formulations for automobile safety bags. The phase state of ammonium nitrate alloys with minor additions of organic substances with crystallographic parameters close to those of ammonium nitrate was studied.     

Phase stabilization of ammonium nitrate by double addition of potassium nitrate and melamine

Methods for providing stabilization of ammonium nitrate and expanding the application field of this oxidizing agent in gas-generating compositions used for various purposes were sought for. The results of a study of the physicochemical properties of ammonium nitrate with a melamine–potassium nitrate double additive introduced by mechanical mixing and crystallization from an aqueous (nonaqueous) solution at the boiling point are presented. The phase diagrams of the ammonium nitrate–melamine and ammonium nitrate–melamine–potassium nitrate systems, based on the results of a differential-thermal analysis, demonstrated that a phase-stable ammonium nitrate can be formed by using the method of crystallization from an aqueous (nonaqueous) solution at the boiling point. The resulting samples were examined by IR spectroscopy and X-ray diffraction analysis, and a conclusion was made that a new thermodynamically stable phase can be formed in the system with individual additives, and the introduction of a double additive leads to a combined effect: a thermodynamically stable crystal structure is formed, with the simultaneous slowing down of the nucleation and growth of a new phase in the course of a phase transformation.     

Green Colorants Based on Energetic Azole Borates

The investigation of green‐burning boron‐based compounds as colorants in pyrotechnic formulations as alternative for barium nitrate, which is a hazard to health and to the environment, is reported. Metal‐free and nitrogen‐rich dihydrobis(5‐aminotetrazolyl)borate salts and dihydrobis(1,3,4‐triazolyl)borate salts have been synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and vibrational spectroscopy. Their thermal and energetic properties have been determined as well. Several pyrotechnic compositions using selected azolyl borate salts as green colorants were investigated. Formulations with ammonium dinitramide and ammonium nitrate as oxidizers and boron and magnesium as fuels were tested. The burn time, dominant wavelength, spectral purity, luminous intensity, and luminous efficiency as well as the thermal and energetic properties of these compositions were measured.     

Steam distillation methods for determination of ammonium,nitrate and nitrite

Steam distillation methods of determining ammonium, nitrate, and nitrite in the presence of alkali-labile organic nitrogen compounds are described. They involve the use of magnesium oxide for distillation of ammonium, ball-milled Devarda alloy for reduction of nitrate and nitrite to ammonium, and sulfamic acid for destruction of nitrite. The methods are rapid, accurate, and precise, and they permit nitrogen isotope-ratio analysis of ammonium, nitrate, and nitrite in tracer studies using ¹⁵N-enriched compounds. They give quantitative recovery of ammonium, nitrate and nitrite added to soil and plant extracts, and appear suitable for analysis of biological materials.     

Technique for the isolation of secondary phases in processed magnesite

The study describes a new wet chemical technique, termed ANM, for the isolation of secondary phases in magnesite processed at a temperature of 1650 degrees C. The major MgO (periclase) phase in processed magnesite was preferentially extracted as ammonium nitrate magnesium double salt by ammonium nitrate in ethanol medium. The residues containing enriched secondary phases were identified by XRD.     

Stripping study of U(VI) from loaded TBP/n-paraffin using ammonium nitrate bearing waste as strippant

Stripping studies of U(VI) from loaded solvent TBP/n-paraffin was carried out using ammonium nitrate solution as strippant. Effects of various stripping parameters such as concentration of ammonium nitrate solution, U(VI) concentration in organic phase, initial pH of strippant, temperature etc. have been investigated in detail. Kinetics of the stripping process by ammonium nitrate was found to be slower than that of stripping with water. It was observed that with the increase in ammonium nitrate concentration in aqueous solution, stripping of U(VI) decreased. With the increase in U(VI) loading in the organic phase, there was an increase in uranium stripping for ammonium nitrate whereas for distilled water it becomes reverse. With the increase in pH of the aqueous ammonium nitrate solution, stripping increased up to a certain pH of 8.5 and after that precipitation of uranium started. Increase in temperature of the biphasic system shows an enhancing effect of U(VI) stripping. Evaluation of thermodynamic data such as ?H indicated that the process is endothermic. Based on the optimized conditions, McCabe–Thiele diagram was constructed for U(VI) stripping using ammonium nitrate solution at room temperature.     

Preparative separation of isoflavone components in soybeans using high-speed counter-current chromatography

The analysis of ionic micro-contamination is of growing importance in the disc drive industry. Through the use of ion chromatography, cleanliness of drive components can be assessed. An objective to improve quantification of highly reactive inorganic ions that exist within the drive environment was implemented. This paper presents a new extraction technique used to determine low levels of ammonium, by microbore ion chromatography. Various chemical compounds within adhesive formulations can be a source of extractable ammonium. By combining this new extraction method with ion chromatography, the percentage of different chemical compounds within adhesive formulations was correlated to the level of extractable ammonium observed.     

Phase stability in the system constituted by ammonium nitrate,potassium dichromate,and alkaline-earth metal nitrates

Methods for modification of ammonium nitrate as an oxidizing agent for ecologically safe solid propellants were sought for and the influence exerted on phase transitions in ammonium nitrate by three-component inorganic additives in which a synergic effect lowering the transition energy is manifested was determined.     

Sequential flow injection analysis of ammonium and nitrate using gas phase molecular absorption spectrometry

A flow injection method on the basis of gas phase molecular absorption is described for the sequential determination of ammonium and nitrate. Two hundred microliters of sample solution is injected into the flow line. For ammonium determination, the sample zone is directed to a line in which reacts with NaOH (13 M) and produces ammonia. But for nitrate determination, the sample zone is passed through the on-line copperized zinc (Zn/Cu) reduction column and produces ammonium ion and in the follows ammonia. The produced ammonia in both cases is purged into the stream of N₂ carrier gas. The gaseous phase is separated from the liquid phase using a gas-liquid separator and then is swept into a flow through cell, which has been positioned in the cell compartment of an UV-Vis spectrophotometer. The absorbance of the gaseous phase is measured at 194 nm. Under selected conditions for sequential analysis of ammonium and nitrate, linear relations were found between the peak heights of absorption signals and concentrations of ammonium (10-650 μg ml⁻¹) and nitrate (20-800 μg ml⁻¹). The limit of detections for ammonium and nitrate analysis were 8 and 10 μg ml⁻¹, respectively. The relative standard deviations of repeated measurements of 50 μg ml⁻¹ of ammonium and nitrate were 2.0, 2.9%, respectively. Maximum sampling rate was about 40 samples/h. The method was applied to the determination of ammonium in pharmaceutical products and the sequential determination of ammonium and nitrate in spiked water samples.     

Use of porous graphitic carbon for the analysis of nitrate ester, nitramine and nitroaromatic explosives and by-products by liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry

A new LC/MS method was developed for the analysis of sixteen different analytes including the most common organic explosives encountered in forensic investigations. The separation was achieved using a porous graphitic carbon (PGC) column with a binary gradient elution. Molecular modeling suggested a possible interpretation for the elution order of explosive compounds on PGC. The introduction of ammonium formate in the mobile phase resulted in the formation of characteristic adduct ions thus enhancing the mass spectrometric detection of nitrate ester and nitramine compounds. Atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) were compared in terms of sensitivity. The final LC/APCI-MS method allowed easy identification of investigated compounds with limits of detection ranging from 0.04 to 1.06 ng/microl. The analysis of simulated forensic samples confirmed the performance of the method.     

Enhancing the strength of granules and thermal stability of ammonium nitrate

The effect of sulfate ions on the physicochemical properties of ammonium nitrate with a dolomite additive was examined. Changes in the rate of the IV → III phase transition, granule strength, number of thermal cycles, and content of ammonium nitrate aerosol in air after the granulation tower were evaluated.     

Effect of chromatographic conditions on liquid chromatographic chiral separation of terbutaline and salbutamol on Chirobiotic V column

In this study, a method for enantioseparation of terbutaline and salbutamol was established using Chirobiotic V column as a stationary phase. Polar ionic mode applying mobile phase containing ammonium nitrate in 100% ethanol, pH 5.1 was found to give the best separation. The salt concentration in the mobile phase and pH value were found to be the most important chromatographic factors affecting separation. Separation of enantiomers of these two basic analytes was complete in less than 10 min without applying ammonium trifluoroacetate (ATFA) or triethylamine (TEA) salts.     

Influence of the nature of molybdenum compounds on the activity of Mo/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and NiMo/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> hydrotreating catalysts

The influence of the nature of molybdenum compounds on the catalytic activity of sulfided NiMo/γ-Al₂O₃ catalysts was studied. The samples were prepared by impregnating the support with mixed aqueous solutions of nickel nitrate and molybdenum-containing compounds: ammonium paramolybdate and the 6-series heteropoly compounds (HPCs) ammonium 6-molybdonickelate (NiMo₆-HPC) and ammonium 6-molybdoaluminate (AlMo₆-HPC). Complexing agents (tartaric acid or a solution of NH₃) were used for stabilizing mixed aqueous ammonium paramolybdate and nickel nitrate solutions and for simultaneously producing an acidic or alkaline medium. The starting molybdenum compounds and catalysts in the oxide form were characterized using IR spectroscopy and x-ray diffraction analysis. The activity of catalysts based on NiMo₆-HPC in the hydrogenolysis of thiophene and in the hydrotreating of the diesel fraction was higher than that of catalysts based on ammonium paramolybdate: at 320°C, the degree of sulfur removal from the diesel fraction was higher by 13–16% and the average degree of hydrogenation of polycyclic aromatic hydrocarbons was higher by 14–15%. It was also found that the use of AlMo₆-HPC does not cause such an effect.     

A Novel Validated Injectable Colistimethate Sodium Analysis Combining Advanced Chemometrics and Design of Experiments

Colistimethate sodium (CMS) is widely administrated for the treatment of life-threatening infections caused by multidrug-resistant Gram-negative bacteria. Until now, the quality control of CMS formulations has been based on microbiological assays. Herein, an ultra-high-performance liquid chromatography coupled to ultraviolet detector methodology was developed for the quantitation of CMS in injectable formulations. The design of experiments was performed for the optimization of the chromatographic parameters. The chromatographic separation was achieved using a Waters Acquity BEH C₈ column employing gradient elution with a mobile phase consisting of (A) 0.001 M aq. ammonium formate and (B) methanol/acetonitrile 79/21 (v/v). CMS compounds were detected at 214 nm. In all, 23 univariate linear-regression models were constructed to measure CMS compounds separately, and one partial least-square regression (PLSr) model constructed to assess the total CMS amount in formulations. The method was validated over the range 100–220 μg mL⁻¹. The developed methodology was employed to analyze several batches of CMS injectable formulations that were also compared against a reference batch employing a Principal Component Analysis, similarity and distance measures, heatmaps and the structural similarity index. The methodology was based on freely available software in order to be readily available for the pharmaceutical industry.     

Solid-liquid phase equilibria of binary salt hydrate mixtures involving ammonium alum

Summary The solid-liquid phase diagrams of binary mixtures of ammonium alum with ammonium iron(III) alum, with aluminum nitrate nonahydrate and with ammonium nitrate and of aluminum sulfate hexadecahydrate with aluminum nitrate nonahydrate are presented. The alum rich branches of the former three-phase diagrams were fitted by the Ott equation. The specific enthalpy of fusion/freezing of some compositions of the former three mixtures was determined by differential drop calorimetry.     

A facile procedure for the one-pot synthesis of unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles

Unsymmetrically 2,5-disubstituted 1,3,4-oxadiazoles were efficiently synthesized from the cyclization-oxidation reaction of acyl hydrazones. Also, the synthesis of the title compounds was achieved by the condensation of acyl hydrazides and aromatic aldehydes in the presence of ceric ammonium nitrate in dichloromethane.     

Palladium extraction from nitrate solutions by tertiary amines and quaternary ammonium salts

The mechanism of palladium extraction by trilaurylamine and trilaurylmethylammonium nitrate from nitric acid solutions was studied. The composition of the extracted compounds was determined by the Job method as well as by organic phase saturation. Both reagents were found to extract palladium as Am₂Pd/NO₃/₄ /Am=ammonium cation/.     

Study of inorganic ammonium compounds in individual marine aerosol particles by laser microprobe mass spectrometry

Ammonia is important in the atmosphere because it neutralizes acidic species. The relative importance of different inorganic ammonium compounds (chloride, nitrate and sulfate) in marine air chemistry was studied by single-particle characterization with the laser microprobe mass analyser. Standard aerosols were generated as a reference for compound identification, based on the fingerprint spectra obtained, and calculation of the relative sensitivity achieved for different ions in a marine aerosol matrix. The relative sensitivity for ammonium was low. Aerosol samples were collected in the Southern Bight of the North Sea under different meteorological conditions and examined for their ammonium compounds. Samples collected during an inversion period with continental influences showed a much higher content in all particles than samples collected under different meteorological conditions, where ammonium was mostly detected in the submicrometer particle-size range.     

High-performance liquid chromatographic determination of pantoprazole and its main impurities in pharmaceuticals

An RP-HPLC method for simultaneous separation and quantification of pantoprazole and its five main impurities in pharmaceutical formulations was developed and validated. The separation was accomplished on a Zorbax Eclipse XDB C18 column (5 microm particle size, 150 x 4.6 mm id) using a gradient with mobile phase A [buffer-acetonitrile (70 + 30, v/v)], and mobile phase B [buffer-acetonitrile (30 + 70, v/v)]. The buffer was 0.01 M ammonium acetate solution with addition of 1 mL triethylamine/L of the solution, adjusted to pH 4.5 with orthophosphoric acid. The eluent flow rate was 1 mL/min, the temperature of the column was 30 degrees C, and the eluate was monitored at 290 nm. Linearity (r = 0.999), recovery (97.6-105.8%), RSD (0.55-1.90%), and LOQ (0.099-1.48 microg/mL) were evaluated and found to be satisfactory. The proposed method can be used for simultaneous identification and quantification of the analyzed compounds in pharmaceutical formulations.     

Method of separating uranium from iron and thorium

Acid leaching of uranium deposits is not a selective process. Sulfuric acid solubilizes iron(III) and half or more of the thorium depending on the mineralog of this element. In uranium recovery by solvent extraction process, uranium is separated from iron by an organic phase consisting of 10 vol% tributylphosphate(TBP) in kerosine diluent. Provided that the aqueous phase is saturated with ammonium nitrate or made 4–5 M in nitric acid prior to extraction. Nitric acid or ammonium nitrate is added to the leach solution in order to obtain a uranyl nitrate product. Leach solutions containing thorium(IV) besides iron are treated in an analogous fashion. Uranium can be extracted away from thorium using 10 vol% TBP in kerosine diluent. The aqueous phase should be saturated with ammonium nitrate and the pH of the solution lowered to 0.5 with sufficient amount of sulfuric acid. In other words, the separation of uranium and thorium depends on the way the relative distributions of the two materials between aqueous solutions and TBP vary with sulfuric acid concentration. Thorium is later recovered from the waste leach liquor, after removal of sulfate ions. Uranium can be stripped from the organic phase by distilled water, and precipitated as ammonium diuranate.