Ammonium Hydroxide Solution Research Articles

A SELECTIVE AND SENSITIVE METHOD DEVELOPMENT AND VALIDATION BY LC-MS/MS APPROACH FOR TRACE LEVEL QUANTIFICATION OF POTENTIAL GENOTOXIC IMPURITY OF BOC EPOXIDE IN ATAZANAVIR SULPHATE DRUG SUBSTANCE

Objective: To develop and validate a selective, sensitive, rapid and accurate method using LC-MS/MS technique to achieve efficient separation between active pharmaceutical ingredient (Atazanavir sulphate) and genotoxic impurity (BOC epoxide).Methods: The quantification was carried out using the column puro sphere star RP 18 e (length 150 mm, internal diameter 4.6 mm, particle size 3.0 µm) with electrospray ionization in multiple reaction monitoring (MRM) detection mode. Eluent-A was 0.1% formic acid in water and eluent-B was 0.1% formic acid and 0.1% ammonium hydroxide solution (25%) in acetonitrile. The isocratic mode of elution was carried out for the elution of impurity with the shorter run time of 6 min. The flow rate was 1.0 ml/min and column oven temperature was maintained 25 °C.Results: The method was validated as per ICH guidelines and arrived the limit of detection and limit of quantification for the potential genotoxic impurity and found to be 0.2 ppm and 0.5 ppm. The developed method was found linear in the concentration range of 0.5 ppm to 6 ppm and accuracy results were within the range. Conclusion: The developed short span method found to be selective, sensitive, precise and accurate for the quantification of the BOC epoxide genotoxic impurity in atazanavir sulphate drug substance.

Fabrication and Properties of InN NPs/Si as a photodetector

Indium nitride InN nanoparticles NPs are synthesized by laser ablation of indium target in ammonium hydroxide solution. The scanning electron microscope SEM, Fourier transforms infrared spectroscopy FTIR, and UV-VIS-NIR spectroscopy were used for investigating the NPs. The FTIR exhibit the presence of In=N bond. The SEM image shows a spherical shape of NPs. The transmission spectra have the maximum edge at 1378nm with band gap was 1.1eV. For optoelectronic properties, InN NPs colloidal was deposited on silicon substrates by drop casting. The characteristics of InN/Si heterojunction have a good rectifying with the spectral Responsivity 0.31 A/W at 750nm and quantum efficiency about 52.7 %.

Tribological Properties of Electrodeposited Ni–Co3O4 Nanocomposite Coating on Steel Substrate

Uniform nanoparticles of cobalt oxide precursors were prepared by the chemical precipitation in which the headspace vapors of ammonium hydroxide solution of known concentration were allowed to bubble through the aqueous solutions of cobalt sulfate, containing appropriate amount of the nonionic surfactant, octylphenoxy poly ethoxy ethanol. Scanning electron microscope (SEM) images showed that uniformity in particle size was dependent upon the applied precipitation conditions. Extensive optimization was therefore performed for the attainment of uniformity in particle size and shape. The amorphous precursor was transformed into crystalline Co3O4 as confirmed by X-ray diffractometry. These particles, with isoelectric point (IEP) at pH ∼ 8.4, were then employed as reinforcement additive for strengthening the electrodeposited nickel matrix. Effect of various parameters, i.e., stirring rate, applied current density, and temperature, was studied on the amount of the codeposited Co3O4 particles in the nanocomposite coatings (Ni–Co3O4) during the electrodeposition process. pH of the coating mixtures was kept below IEP value of Co3O4 so that the latter particles carried net positive surface charge. The coated surfaces were subjected to various tests, i.e., microhardness, wear/friction, and corrosion. Results revealed that irrespective of the amount of the embedded Co3O4 particles, nanocomposite coatings demonstrated superior performance as compared to pure nickel coatings.

Dissolution mechanism of cellulose in quaternary ammonium hydroxide: Revisiting through molecular interactions

Quaternary ammonium hydroxide (QAH) solution has been used to dissolve cellulose and made great progress in recent years. While, its cellulose dissolution mechanism is still in unclear. Here, series of QAH with varied cationic alkyl chains were chosen for the investigation. The solubility of cellulose in QAH was measured, which allowed us to study the effect of cationic structure on cellulose dissolution. Also, the Kamlet-Taft parameters as well as 1D and 2D NMR analyses of QAH-cellulose/cellobiose system were measured. Results indicated that both the anions and cations were essential for cellulose dissolution: anions were responsible for interaction with hydroxyl protons on cellulose, re-forming hydrogen bonds and leading to structural disruption in cellulose; α-methylene on cations would interact with electropositive carbon atoms on cellulose via electrostatic or Van der Waals force, facilitating inner-structural disruption. The synergistic effects eventually resulted in complete disruption of hydrogen bonds and thus effective dissolution of cellulose.

Lysergic acid amide as chemical marker for the total ergot alkaloids in rye flour – Determination by high-performance thin-layer chromatography–fluorescence detection

Ergot alkaloids are generally determined by high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FLD) or mass selective detection, analyzing the individual compounds. However, fast and easy screening methods for the determination of the total ergot alkaloid content are more suitable, since for monitoring only the sum of the alkaloids is relevant. The herein presented screening uses lysergic acid amide (LSA) as chemical marker, formed from ergopeptine alkaloids, and ergometrine for the determination of the total ergot alkaloids in rye with high-performance thin-layer chromatography–fluorescence detection (HPTLC–FLD). An ammonium acetate buffered extraction step was followed by liquid-liquid partition for clean-up before the ergopeptine alkaloids were selectively transformed to LSA and analyzed by HPTLC–FLD on silica gel with isopropyl acetate/methanol/water/25% ammonium hydroxide solution (80:10:3.8:1.1, v/v/v/v) as the mobile phase. The enhanced native fluorescence of LSA and unaffected ergometrine was used for quantitation without any interfering matrix. Limits of detection and quantitation were 8 and 26μg LSA/kg rye, which enables the determination of the total ergot alkaloids far below the applied quality criterion limit for rye. Close to 100% recoveries for different rye flours at relevant spiking levels were obtained. Thus, reliable results were guaranteed, and the fast and efficient screening for the total ergot alkaloids in rye offers a rapid alternative to the HPLC analysis of the individual compounds.

Synthesis and characterization of ZnO nanostructures with varying morphology

Uniform fine particles of zinc oxide were prepared in three different morphologies and sizes by the controlled precipitation process from aqueous solutions of zinc nitrate in the presence of ethylene glycol. Ammonium hydroxide solution was used as the precipitant. Composition of the reactant solution, pH and temperature significantly affected the particle uniformity with respect to shape and size. Uniformity in the particles morphological feature was achieved under a narrow set of experimental conditions. pH of the reactant solutions and isoelectric point of zinc oxide were considered the master variables, controlling the particle size. One of the batch of the as-prepared zinc oxide particles was calcined at \(750{^{\circ }}\hbox {C}\), which increased its crystallinity, changed its various lattice parameters, Zn–O bond length and preferred orientation of the crystal hkl planes. Calcination had little effect on the original morphology of the zinc oxide particles.

Extracting silver from anode slime after lead and gold separations

Anode slime, a byproduct from the process of copper electrorefining into the copper cathode, contains several valuable elements that can be extracted after Cu and Pb separations. Another alternative route for extracting the precious metals is still needed in terms of gaining more economical route. This research aims to seek the new route to extract the precious metals, especially silver from anode slime. In these experiments, the anode slime was obtained from PT Smelting Gresik. The lead was separated to produce the residue which was then chlorinated to extract the gold. Later the residue was used for extracting the silver by dissolving it in ammonium hydroxide solution with varying time dissolutions and concentrations and later dissolving in hydrochloric acid to form silver chloride which was reduced to metallic silver. These experiments had two trials. The first one related to directly using residual chlorination after gold separation and the second one employed the same residual chlorination but processed through de-chlorination by adding sodium carbonate. The result showed that the highest silver recovery of 53.56% related to 5 M ammonium hydroxide concentration, the temperature of 30°C, dissolution time of 60 minutes. Recovery of 53.78% was achieved at 7 M ammonium hydroxide, the temperature of 30°C, dissolution time of 60 minutes. The feed of those experiments came from direct residual chlorination, while chlorination residue that underwent de-chlorination produced silver recovery of 94.95% with leaching conditions of 5 M ammonium hydroxide, the heating temperature of 30°C and leaching time of 60 minutes. The latest recovery was relatively high resulted in the process could be scaled up to a continuous system.

Preparation and Characterization of Zirconia Nanomaterial as a Molybdenum-99 Adsorbent

The present study deals with the synthesis and characterization of ZrO 2 nanomaterial which can be used as an adsorbent for Molybdenum-99 ( 99 Mo). The adsorbent can potentially be utilized as the material for 99 Mo/ 99m Tc generator column. Using the sol-gel method, monoclinic nanocrystalline zirconia was synthesized from zirconium oxychloride in isopropyl alcohol reacted with ammonium hydroxide solution in isopropyl alcohol resulting in a white gel. The gel was subsequently refluxed for 12 hours at ~95°C and pH at ~4 and then dried at 100°C. The drying gel was then calcined at 600°C for two hours. Meanwhile the orthorhombic nanocrystalline zirconia was obtained by reacting zirconium oxychloride solution with 2.5 M ammonium hydroxide solution which resulted in a white gel. The gel was then refluxed for 24 hours at ~95°C and pH at ~11 and then dried at 100°C. The drying gel was then calcined at 600°C for two hours. These materials were characterized using FT-IR spectroscopy, X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). The Scherrer method is used for determination of crystallite size. The FT-IR spectra for both materials show absorption peak at 450-500 cm -1 which are attributed to Zr-O bond. The XRD pattern of monoclinic nanocrystalline form shows crystalline peaks at 2θ regions of 28.37°, 31.65°, 34°, 36°, and 50.3° with average crystallite size of 2.68 nm. Meanwhile, the XRD pattern of orthorhombic nanocrystalline form shows crystalline peaks at 2θ regions of 30°, 35°, 50°, and 60° with average crystallite size of 0.98 nm. The TEM micrograph indicates that the zirconia nanomaterials prepared were quite uniform in size and shape. Received: 1 2 November 2015; Revised: 9 Septem ber 2016 ; Accepted: 20 September 2016

Conditioning Safety Index of Ni-Rich Cathode Oxides for Lithium Ion Batteries

Ni-rich cathode materials with high energy density has degradation issue of electrochemical performance due to the significant side reaction between electrolyte and cathode. To solve this, a Full Concentration Gradient (FCG) materials consisting of a high-Ni core and a relatively high-Mn outer layer was designed to provide improved stability as well as cycle life characteristic. However, a Ni-rich core still has some possibilities to be contact with electrolyte, especially if the particle in the core part is unexpectedly porous. We found the strategy to tune the particle porosity by controlling a feed rate of transition metal sulfate solutions and ammonium hydroxide solution during co-precipitation synthesis using Continuous Stirred Tank Reactor (CSTR). Additionally, the effect of surfactant was studied in the standpoint of the electrode stability. The structural characteristics was compared for the materials obtained by different feed rate with analysis of by X-ray diffraction, electron microscopy and dynamic light scattering. The interfacial kinetic reaction between the delithiated Ni-rich cathode and a nonaqueous electrolyte was investigated by our home-built high-precision leakage current measurement system. The result of this study indicated a different reaction phenomenon and further implies that the safety of Ni-rich cathode by co-precipitation could be controlled.

NO oxidation over Co-La catalysts and NO x reduction in compact SCR

A series of Co-La catalysts were prepared using the wet impregnation method and the synthesis of catalysts were modified by controlling pH with the addition of ammonium hydroxide or oxalic solution. All the catalysts were systematically investigated for NO oxidation and SO2 resistance in a fixed bed reactor and were characterized by Brunanuer–Emmett–Teller (BET) method, Fourier Transform infrared spectroscopy (FTIR), X–ray diffraction (XRD), Thermogravimetric (TG) and Ion Chromatography (IC). Among the catalysts, the one synthesized at pH = 1 exhibited the maximum NO conversion of 43% at 180°C. The activity of the catalyst was significantly suppressed by the existence of SO2 (300 ppm) at 220°C. Deactivation may have been associated with the generation of cobalt sulfate, and the SO2 adsorption quantity of the catalyst might also have effected sulfur resistance. In the case of the compact selective catalytic reduction (SCR), the activity increased from 74% to 91% at the highest gas hourly space velocity (GHSV) of 300000 h–1 when the NO catalyst maintained the highest activity, in excess of 50% more than that of the standard SCR. Open image in new window

Auto-ignition of a carbon-free aqueous ammonia/ammonium nitrate monofuel: A thermal and barometric analysis

A carbon-free aqueous solution of ammonium hydroxide and ammonium nitrate (AAN) was studied using differential thermal and barometric analyses under initial N2 pressure of up to 4.6MPa. The suggested nitrogen-based monofuel exhibited three distinct exothermic processes during heating. Their onset temperatures increased as the initial nitrogen pressure was raised. In addition, a higher extent of reaction was observed at high nitrogen pressures. This result was attributed to the effect of mass diffusion in the system, which decreased at higher pressures. Using a modified mechanism for the combustion of nitrogen-based fuels, the thermal ignition process was simulated. The resulting auto-ignition temperature values were shown to be in good agreement with experiments at initial nitrogen pressures of up to 2.3MPa. Above this pressure, the agreement between experimental and model results was hampered by mass diffusion effects. Using the modified mechanism, the main chemical pathways prior to auto-ignition of AAN were identified and the reactions leading to ignition were discussed. This paper presents for the first time the auto-ignition of AAN and explores the combustion chemistry of this carbon-free monofuel.

Leaching gold by reactive flow of ammonium thiosulfate solution in high aspect ratio channels: Rate, passivation, and profile

Dissolution of interfacial materials in spatially confined flow is an important physicochemical process. Here, we present a study of gold leaching, where the gold layer is removed from a microchannel wall within a high aspect ratio channel (8μm×4mm cross-section; 1:500). The etchant is an aqueous solution of sodium thiosulfate, ammonium hydroxide, and copper sulfate. Optical transmission of the gold layer was used for quantitative, in situ, and real-time measurement of the layer thickness and its spatial uniformity along and across the channel. The onset of etching is not immediate, indicating that a passivation layer exists (even on ‘bare’ gold layers, where etching was delayed by approx. 2min). Pre-treatment of the gold surface with an incomplete alkane thiol self-assembled monolayer (11-mercapto-1-undecanol) led to a later onset of etching and slower etching rate (5.5nm/min) compared with that on ‘bare’ gold (6.2nm/min). Flow profiles are reflected in the observed etch profiles. Upstream and downstream differences in etch rate are magnified for intermediate copper sulfate concentrations. This novel technique offers quantitative, in situ and real time monitoring of etching under controlled conditions in continuous laminar flow through microchannels, providing a valuable tool to understand various reactive processes in spatial confinement, such as heap or in-situ leaching in mineral processing.

Water Evaporation-Induced Self-Assembly of Hierarchical CuO/MnO2 Composite Nanospheres and their Applications in Lithium-Ion Batteries

In this paper, hierarchical CuO/MnO2 composite hollow nanospheres have been successfully fabricated by water evaporation-induced self-assembly through a redox transformation reaction between Cu2O nanospheres and KMnO4 solution at 120[Formula: see text]C for 6[Formula: see text]h, followed by removing the residual Cu2O cores with ammonia hydroxide solution. The outstanding feature of this method is that the reaction system is in a dynamic environment due to the evaporation of the solvent water, which benefits the self-assembly of nanostructures to form hierarchical structures. Both Kirkendall effect and Ostwald ripening mechanism are suggested to be responsible for the formation of the hierarchical CuO/MnO2 nanocomposites according to the characterization results. The electrochemical properties of the products were studied, and the results show that the hierarchical CuO/MnO2 hollow nanospheres exhibit high capacity and good rate performance (a stable capacity of about 480[Formula: see text]mAh[Formula: see text]g[Formula: see text] after 80 cycles of variable charging rate), which is probably attributed to the hierarchical hollow nanostructures.

Effects of etching conditions on surface morphology of periodic inverted trapezoidal patterned Si(100) substrate

In this paper, the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide (TMAH) solution with isopropyl alcohol (IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A series of experiments are performed by changing TMAH concentration, IPA concentration, etching temperature and etching time. The structure of inverted trapezoidal patterns and roughness of the bottom surface are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results show that with TMAH concentration increases, the roughness of bottom surface will decrease. The addition of IPA into TMAH solution improves the morphology of the bottom surface significantly. Low temperature is beneficial to get a smooth bottom surface. Furthermore, etching time can change the bottom surface roughness. A model is proposed to explain the etching processes. The hillock area ratio of the bottom surface has the same tendency as the etching area ratio. Finally, smooth silicon inverted trapezoidal patterns are obtained for epitaxial growth of GaN-based light emitting diode (LED) devices.

Facile One-Step Synthesis of Silica Micro- and Nanotubes and Their Functionalization

Rectangular silica nanotubes (NTs) and microtubes (MTs) were synthesized by a simple one-step sol-gel hydrolysis reaction. Although silica nanotubes are usually prepared in the presence of a template (e.g. metal rods), the proposed procedure eliminates the need for such template insertion and, subsequently, no further etching step is required.The Stöber silica nanoparticles (NPs) synthesis employs ammonium hydroxide solution as the base for tetraethyl orthosilicate (TEOS) hydrolysis, leading to the formation of discreet uniform NPs. Replacing ammonium hydroxide with sodium bicarbonate resulted in the formation of silica NTs with unique rectangular shape, both for the tube (external) and the lumen (internal cavity). On the other hand, replacing ammonium hydroxide with ammonium carbonate led to the formation of larger silica MTs with similar geometry. The influence of parameters such as: monomer concentration, base concentration, base:monomer ratio, temperature and solvent, on tube formation was investigated. This procedure was also utilized to prepare mesoporous and functionalized NTs and MTs with unique characteristics as omniphobic coatings.A proposed mechanism for the production of silica rectangular NTs and MTs via sheet folding is offered, based on our findings.

Extraction of Thiophenic Sulfur Compounds from Model Fuel Using a Water-Based Solvent

Thiophene, benzothiophene, and dibenzothiophene were extracted from isooctane using water and aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, sodium hydroxide, ammonium hydroxide, and sodium chloride at different concentrations, as solvents or extractants. The sulfur compound in isooctane at a definite concentration comprises model fuel. It was observed that the extraction ability of water is enhanced by adding those solutes or reagents. The aim of this work is to establish water-based solutions as an economic extractant for desulfurization of model fuel containing thiophenic sulfur compounds, by choosing the appropriate concentration of those aqueous extractants and using them at the most suitable extractive condition. The best result was obtained from aqueous hydrochloric acid solution, whose maximum sulfur removal efficiency toward thiophene, benzothiophene, and dibenzothiophene was 50, 28.2, and 26.8%, respectively. The effect of operational parameters on extraction, s...

The nitrogen economy: Economic feasibility analysis of nitrogen-based fuels as energy carriers

Production of transportable and environmentally friendly synthetic chemical fuels using hydrogen produced by water splitting, using renewable energy will facilitate energy storage and incorporation of renewable energy into the grid. Both carbon and nitrogen can serve as hydrogen carriers leading to carbon- or nitrogen-based fuels carriers. Although the carbon route is vastly reported, the nitrogen-based analog is only scarcely described in the literature, and its economic potential is completely overlooked. Using levelized cost of storage analysis, this work evaluates for the first time the economic feasibility of a nitrogen economy, where liquid nitrogen-based fuels serve as alternative hydrogen carriers. The results indicate that an aqueous solution of ammonium hydroxide and urea is competitive with other future large-scale energy storage solutions such as methanol and batteries. At a hydrogen price below 2.5$/kg, this fuel can be competitive with currently-used mature technologies.

In situ hydrazine reduced silver colloid synthesis – Enhancing SERS reproducibility

Herein we report a novel strategy for the in situ synthesis of the silver colloids for LoC-SERS applications. Silver nanoparticles are obtained in a segmented flow based glass microfluidic chip by the reduction of silver ions with hydrazine in ammonium hydroxide solution. Citrate ions are used as protecting agents. The synthesized nanoparticles are characterized by UV-VIS spectroscopy, SEM and TEM imaging. The SERS performance of the in situ synthesized nanoparticles is tested by using adenine as a test analyte right after the colloid synthesis. Reproducibility is tested by repeating the measurements three times at independent days applying the same measurement conditions. In comparison with nanoparticles synthesized in a conventional strategy i.e. in a large batch, chip synthesized nanoparticles show a better day-to-day and long-term reproducibility, lower detection limits and broader working ranges. The great advantage offered by the in situ synthesized colloids combined with the already proven potential of LoC-SERS for bioanalytics, raises the possibility of the employment of LoC-SERS as a fast and sensitive analytic tool in a plethora of applications.

Novel continuous flow synthesis, characterization and antibacterial studies of nanoscale zinc substituted hydroxyapatite bioceramics

Calcium phosphates predominantly hydroxyapatite (HA) has extensively been used as bone substitute material and as coatings on metallic implants because of its high biocompatibility and bioactivity in bone mineralization. In order to enhance bioactivity of HA, hydroxyapatite has been substituted with divalent cations and anions. In this research, zinc substituted hydroxyapatite powder (<100nm) was synthesized from aqueous solution of calcium nitrate tetrahydrate (with different concentration of Zn ions) and diammonium hydrogen phosphate in the presence of ammonium hydroxide solution through a novel continuous plastic flow synthesis (CPFS) at 70°C in 5min residence time at pH 11. The obtained powders were physically characterized using transmission electron microscopy (TEM), Scanning electron microscopy (SEM), BET surface area analysis, X-ray powder diffraction analysis (XRD), and FTIR and Raman spectroscopy. In addition, the particle size was evaluated by Dynamic light scattering (DLS). The chemical structural analysis of all as prepared samples was done using X-ray photoelectron spectroscopy (XPS).The present study showed that all nanoscale particulates had rod like morphology (at low Zn concentration), which changed to semispherical morphology with increasing Zn contents. It was also investigated that zinc substituted hydroxyapatite gave better antibacterial protection than pure HA. Thus, the CPFS system facilitated rapid production of high surface area nanoscale crystals of hydroxyapatite modified by Zn ions with controlled particle properties (crystallinity, size, shape) at (near) ambient conditions.

One‐Pot Multicomponent Synthesis of Novel 2‐Tosyloxyphenylpyrans under Green and Conventional Condition with Anti‐inflammatory Activity

A mild, efficient, and environmentally green protocol for the synthesis of 2‐tosyloxyphenylpyran derivatives 3, 4, 5, 6, 7, 8, 9, 10, 11 via reaction of 2‐tosyloxybenzaldehyde (1) with malononitrile and some ketonic reagents in one‐pot, three component reaction within few minutes under stirring in methanol in presence of ammonium hydroxide solution or ultrasonic irradiation. On the other hand, the same products 3, 4, 5, 6, 7, 8, 9, 10, 11 were obtained by traditional method, on treatment of 2‐tosyloxybenzilidinemalononitrile (2) with the same ketonic reagents in refluxing ethanol in presence of TEA. 2‐Tosyloxyphenylpyranopyrazoles 12 and 13 were obtained via treatment of compound 1 with malononitrile, hydrazine hydrate or phenyl hydrazine and ethyl acetoacetate, in one‐pot, multicomponent reaction (MCRs). The structures of the new compounds were elucidated by elemental and spectral analyses. The newly synthesized compounds showed promising anti‐inflammatory activity.