Aqueous Ammonium Hydroxide Research Articles

Preparative isolation of cordycepin, N(6)-(2-hydroxyethyl)-adenosine and adenosine from Cordyceps militaris by macroporous resin and purification by recycling high-speed counter-current chromatography.

In this study, cordycepin, N(6)-(2-hydroxyethyl)-adenosine (HEA) and adenosine from the fruiting bodies of Cordyceps militaris were separated by using macroporous resin NKA-II adsorption. The parameters of static adsorption were tested and the optimized conditions were as follow: the total adsorption time was 12h, 50% ethanol was used for desorption and the desorption time was 9h. The crude sample that was prepared by macroporous resin NKA-II contained 3.4% cordycepin, 3.7% HEA and 4.9% adenosine. Then the crude sample was further purified by recycling high-speed counter-current chromatography (HSCCC) with ethyl acetate, n-butanol, 1.5% aqueous ammonium hydroxide (1:4:5, v/v/v) as the optimized two-phase solvent system. Three nucleosides including 15.6mg of cordycepin, 16.9mg of HEA and 23.2mg of adenosine were obtained from 500mg of crude sample in one-step separation. The purities of three compounds were 98.5, 98.3 and 98.0%, respectively, as determined by high performance liquid chromatography.

Nano-chitosan Utilization for Fresh Yellowfin Tuna Preservation

Chitosan utilization as a preservative agent for freshly caught fish has been studied intensively during the last ten years in Indonesia, but the effort was concentrated more on ponds-raised fresh water fish. In this paper we report our preliminary results of a study on using chitosan in the form of nanoparticle (nano-chitosan) to improve the shelf life of freshly caught wild young yellowfin tuna (YFT- Thunnus albacares, Bonnaterre 1788). Pharmaceutical grade chitosan was dissolved in 0.2 mM aqueous acetic acid and aqueous ammonium hydroxide was added to reach a certain value of pH at which 1% concentration of nano-chitosan particles was obtained. The YFT samples were immersed for 30 min in aqueous dispersion of nano-chitosan, and incubated afterwards at two different temperature settings (4°C and 28°C). The fish deterioration was measured in terms of Total Volatile Base (TVB) and bacterial Total Plate Count (TPC), with supporting data taken including organoleptic assessment, pH and water content. The nano-chitosan did not seem to decrease the number of bacteria. However, the TVB data indicated that nano-chitosan treatment significantly suppressed the bacteria activity and the effect was more pronounced at 28°C.

Fabrication and Characterization of Barium Doped Ceria Nanopowders by a Solvothermal Processing

Ba doped CeO2 nanopowders were prepared under mild temperature and pressure conditions by precipitation from metal nitrates with aqueous ammonium hydroxide. Spherical Ba doped CeO2 nanopowders were obtained with reaction at the temperature range of 210°C to 230°C for 6 h. The average size of the synthesized Ba doped CeO2 powders were below 10 nm and its distribution was narrow. The XRD pattern showed that the synthesized Ba doped CeO2 powders were crystalline with cubic phase of CeO2. This study has shown that the synthesis of Ba doped CeO2 nanopowders is possible under mild temperature and pressure conditions in ethylene gylcol solution. The effects of synthesis parameters, such as the solvent ratio of starting solution, pH of starting solution, reaction temperature and time, are discussed.

Synthesis and Characterization of Nickel Powders by a Solvothermal Processing

Nickel powders were prepared under solvothermal condition by precipitation from metal nitrates with aqueous ammonium hydroxide. The powders were obtained at in a temperature range of 190-250 oC for 6h. The morphology and size of nickel powders were studied as a function of reaction temperature. The synthesis of nickel crystalline particles is possible under a solvothermal conditions in ethylene glycol solution. Characterization of the synthesized nickel powders were studied by XRD, SEM(FE-SEM) and TG/DSC. X-ray diffraction analysis of the synthesized powders indicated the formation of nickel structure after reaction. The average crystalline sizes of the synthesized nickel powders were in the range of 200-1000 nm; and the distribution of the powders was broad. The shape of the synthesized nickel particles was almost spherical. The morphology of synthesized nickel powders changed with reaction condition. It was possible to synthesize nickel powders directly in ethylene glycol without reducing agent.

Addition of ammonium hydroxide as formaldehyde scavenger for sesenduk (Endospermum diadenum) wood compregnated using phenolic resins

Compregnated sesenduk (Endospermum diadenum) was produced using low and medium molecular weight phenol formaldehyde resin. 0, 1, 1.5 and 3 % of aqueous ammonium hydroxide (NH3·H2O) were incorporated into the resin to act as formaldehyde scavenger. A maximum of 85.7 % reduction in formaldehyde emission was recorded, but the mechanical and physical properties of the treated sesenduk wood were negatively affected by the ammonium hydroxide addition.

Osage Orange (Maclura pomifera L.) Seed Oil Poly(α-hydroxydibutylamine) Triglycerides: Synthesis and Characterization.

Milled Osage orange seeds (Maclura pomifera (Raf.) Schneid) were Soxhlet extracted with hexane, and portions of the extract were treated with activated carbon before solvent removal. The crude oil was winterized and degummed by centrifugation at low temperature. Decantation of the centrifugate gave an admixture of the triglycerides and free fatty acids. The free fatty acid content of the oil was removed when portions of the admixture were diluted with hexane and shaken with cold aqueous ammonium hydroxide (0.1 M) solution. The desiccant-dried organic phase was concentrated under reduced pressure to give the cleaned Osage orange triglyceride after solvent removal by rotary evaporation at 67 °C. Epoxidation of the resulting cleaned triglyceride was effected by reaction with in situ generated peroxy performic acid in H2O2. The oxirane rings of the derivatized oil were then opened using N,N-dibutylamine catalyzed by anhydrous ZnCl2 to afford the poly(α-hydroxydibutylamine) triglyceride. The purpose of this work was to derivatize and thereby stabilize this highly unsaturated tree oil for its eventual use in lubrication applications.

Determination of Yohimbine in Yohimbe Bark and Related Dietary Supplements Using UHPLC-UV/MS: Single-Laboratory Validation.

A single-laboratory validation was performed on a practical ultra-HPLC (UHPLC)-diode array detector (DAD)/tandem MS method for determination of yohimbine in yohimbe barks and related dietary supplements. Good separation was achieved using a Waters Acquity ethylene bridged hybrid C18 column with gradient elution using 0.1% (v/v) aqueous ammonium hydroxide and 0.1% ammonium hydroxide in methanol as the mobile phases. The method can separate corynanthine from yohimbine in yohimbe bark extract, which is critical for accurate quantitation of yohimbine in yohimbe bark and related dietary supplements. Accuracy of the method was demonstrated using standard addition methods. Both intraday and interday precisions of the method were good. The method can be used without MS since yohimbine concentration in yohimbe barks and related dietary supplements are usually high enough for DAD detection, which can make it an easy and economical method for routine analysis of yohimbe barks and related dietary supplements. On the other hand, the method can be used with MS if desired for more challenging work such as biological and/or clinical studies.

Facile and Rapid Deprotection Conditions for the Cleavage of Synthetic Oligonucleotides from 1,4-Anhydroerythritol-Based Universal Polymer Support

In our previous report [Kumar, P.; Dhawan, G.; Chandra, R.; Gupta, K.C. Polyamine-assisted rapid and clean cleavage of oligonucleotides from cis-diol bearing universal support. Nucl. Acids Res. 2002, 30, e130 (1-8)], we demonstrated polyamine-mediated deprotection of oligonucleotides from cis-diol group bearing universal polymer support (I). However, vulnerability of the conventional dCbz to modifications under these conditions compelled us to employ dCac during synthesis of oligonucleotide using conventional synthons. Here, a new set of simple and rapid deprotection conditions has been developed for the complete cleavage of oligonucleotides from the 1,4-anhydroerythritol-based universal polymer support employing conventional dCbz synthon. Using manganese-imidazole complex in aqueous ammonium hydroxide (∼30%), fully deprotected oligonucleotide sequences were obtained in 40 min, which were analyzed on reverse phase-HPLC and compared with the standard oligomers in terms of their retention time. Finally, their biological compatibility was established by analyzing PCR amplified products of npsA gene of N. meningitidis.

Determination of surface energies and acidity‐basicity numbers of protonated and deprotonated forms of poly(sulfonic acid diphenyl aniline) by inverse gas chromatography

Protonated form of poly(sulfonic acid diphenyl aniline) (p‐PSDA) was synthesized through oxidative chemical polymerization of sodium salt of diphenylamino‐4‐sulfonic acid in hydrochloric acid and then, its deprotonated form (PSDA) was obtained by neutralization with aqueous ammonium hydroxide solution. The samples were characterized by thermal analysis and Fourier Transform Infrared, Ultraviolet‐visible, 1H‐NMR spectroscopy techniques. Their dispersive surface energies as well as surface acidity and basicity were determined by inverse gas chromatography at temperatures between 313 and 353 K. The dispersive surface energy of p‐PSDA was found to be considerably lower but it increased with temperature while that of PSDA was close to those of conventional polymers and decreased slightly with temperature. According to the Schreiber's procedure, the surfaces of p‐PSDA and PSDA were found to be acidic and amphoteric, respectively. It was observed from the electron microscope images p‐PSDA chains can form self‐organized circular polydisperse micro‐sized aggregates in aqueous solutions while PSDA cannot self‐organize to form individual aggregates. POLYM. ENG. SCI., 55:1246–1254, 2015. © 2015 Society of Plastics Engineers

Graphene-derivatized silica as an efficient solid-phase extraction sorbent for pre-concentration of fluoroquinolones from water followed by liquid-chromatography fluorescence detection

This work presents a novel analytical method based on graphene for the determination of five widely used fluoroquinolones (FQs) in aqueous matrices. The procedure entails solid-phase extraction (SPE) on graphene-derivatized silica (200mg), followed by liquid chromatography with fluorescence detection. Monolayer graphene oxide (GO) flakes were covalently bonded onto aminopropyl silica microparticles, and then treated with aqueous hydrazine to obtain the reduced GO (RGO). The final material (RGO–silica) was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and BET analysis, and for the first time evaluated as mixed-mode sorbent for the SPE of FQs from natural waters. Accuracy was studied on tap/raw river water in the concentration range 5–10,000ngL−1, obtaining mean absolute recoveries from 72 to 118%. The inter-day precision was good, showing relative standard deviations (RSDs) in the range 5–15%. Sample volumes up to 1L provided enrichment factors up to 1000, achieving accurate quantification of concentrations as low as 5ngL−1. The analytes were simultaneously and quantitatively eluted from the RGO–silica cartridge in a single fraction by using acetonitrile combined with aqueous tetrabutyl ammonium hydroxide. The batch-to-batch reproducibility was verified on three independently prepared RGO–silica samples. RGO–silica was advantageous in terms of adsorption capacity and reusability with respect to commercial sorbents; the cartridge proved to be reusable for at least 10 consecutive extractions, with no significant loss of efficiency (recovery >70%). The analytical procedure was applied to the determination of FQs in actual environmental waters.

Quantitative determination of bromine and iodine in food samples using ICP-MS.

Trace concentrations of bromine and iodine in food samples and certified reference materials (CRMs) were determined by an inductively coupled plasma-mass spectrometry (ICP-MS) technique after low-power microwave digestion and extraction into an aqueous quaternary ammonium hydroxide solution. The recovery after sample preparation was quantitative. The internal standard for the measurement of the analyte on ICP-MS was optimized in this study. The detection limits were 0.19 and 0.68 ng g(-1) for I and Br, respectively, when a 10 ng g(-1) Te solution as an internal standard was used, applying the signal of (125)Te. The high recovery and reproducibility are sufficient for the quantitative analysis of these elements, and the analytical procedure is recommended for the analysis of Br and I in various kinds of bio-samples.

Self-termination in the gas-phase layer-by-layer growth of an aza silane and water on planar silicon and nylon substrates

The authors report the gas phase, layer-by-layer deposition of an organosilane (N-n-butyl-aza-2,2-dimethoxysilacyclopentane, 1) and either water or aqueous ammonium hydroxide onto two substrates: Si/SiO2 and nylon. This process results in smooth, water resistant, inorganic-organic barrier layers. The layer-by-layer deposition of 1 appears to be self-limiting to a few nanometers, which may make it useful where ultrathin films of controllable dimensions and uniformity are desired. The authors are unaware of another thin film system that has these properties. Films were characterized by spectroscopic ellipsometry, water contact angle goniometry, x-ray photoelectron spectroscopy, and atomic force microscopy. Interestingly, film thicknesses on nylon were much higher than on silicon, and films prepared in the presence of the ammonia “catalyst” were thinner than those prepared with water. Test circuits coated only with a fluorosilane showed higher penetration of water compared to those coated with a barrier layer of 1/H2O and the fluorosilane.

Recycling gold nanohole arrays

The authors report the impact of common cleaning methods on the stability of gold nanohole arrays used as extraordinary optical transmission surface plasmon resonance sensors. Their optical sensitivity, physical structure, and surface contamination levels were measured before and after multiple cycles of monolayer adsorption and removal with various wet chemicals (sulfochromic acid, piranha, or ammonium hydroxide: hydrogen peroxide) and dry oxygen plasma etchants. While these oxidative chemical and plasma etches remove organic monolayers and other contaminants, the oxidation and associated heating also damages the gold nanostructures to varying degrees. The authors observed decreases in the arrays' optical sensitivities via changes in the shapes and positions of their surface plasmon resonance peaks. The optimum recycling process was a room temperature, aqueous ammonium hydroxide: hydrogen peroxide treatment (15 min) commonly referred to as Radio Corporation of America Clean 1, followed by immersion in dilute nitric acid (0.1M, 30 min). This method was effective at removing an alkanethiol self-assembled monolayer of 11-mercaptoundecanoic acid; after six recycles, no loss in optical sensitivity was detected with minimal changes in the gold film thickness (−10%), hole area (−10%), and hole circularity (+6%).

Synthesis of microspheres of triuranium octaoxide by simultaneous water and nitrate extraction from ascorbate-uranyl sols.

A new method for synthesis of uranium oxide microspheres (diameter <100 μm) has been developed. It is a variant of our patented Complex Sol–Gel Process, which has been used to synthesize high-quality powders of a wide variety of complex oxides. Starting uranyl-nitrate-ascorbate sols were prepared by addition of ascorbic acid to uranyl nitrate hexahydrate solution and alkalizing by aqueous ammonium hydroxide and then emulsified in 2-ethylhexanol-1 containing 1v/o SPAN-80. Drops of emulsion were firstly gelled by extraction of water by the solvent. Destruction of the microspheres during thermal treatment, owing to highly reactive components in the gels, requires modification of the gelation step by Double Extraction Process—simultaneously extraction of water and nitrates using Primene JMT, which completely eliminates these problem. Final step was calcination in air of obtained microspheres of gels to triuranium octaoxide.

Sensor based on silicon microchannel resistor

The work presented here is on manufacturing a sensing structure based on ordered microchannel silicon, for electrophysical detection of liquids. The behavior in time of various organic and inorganic matter (deionized water, ethanol, aqueous ethanol solutions, acetic acid, and ammonium hydroxide) applied to a porous body was studied by the method of measuring the conductivity of a microchannel membrane (a sensing element of a sensor). It was found that a microchannel resistor had a specific response for any liquid applied drop-wise to the sensing element. The proposed electrophysical method allowed us to identify the liquids with which the sensor interacted.

Determination of swainsonine in the endophytic Undifilum fungi by high-performance liquid chromatography with evaporative light-scattering detector

Endophytic Undifilum oxytropis found within toxic locoweeds (Astragalus and Oxytropis spp.) produces the indolizidine alkaloid swainsonine, which is responsible for locoism in grazing animals. The aim of the current study is to establish an easy and accurate method for the determination of swainsonine in the endophytic Undifilum fungi. High-performance liquid chromatography (HPLC) with evaporative light-scattering detector (ELSD) was used for the assay of swainsonine in this study for the first time. The HPLC conditions were Waters XBridge hydrophilic interaction liquid chromatography column using acetonitrile-5mM ammonium acetate (1:1, vol/vol) containing 0.02% (vol/vol) aqueous ammonium hydroxide as mobile phase at a flow rate of 0.5mL/min. ELSD conditions were optimized at nebulizer-gas flow rate of 25psi and drift tube temperature of 55°C. The method was validated to achieve the satisfactory precision and recovery, and the calibration range was 15.625–250μg/mL. Application of the developed analytical procedure to determine swainsonine content in the endophytic Undifilum fungi samples ensured its suitability for the routine analysis of swainsonine.

Synthesis and Characterization of Y2O3Powders by a Modified Solvothermal Process

<TEX>$Y_2O_3$</TEX> nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently, many studies have focused on controlling the size and morphology of <TEX>$Y_2O_3$</TEX> in order to obtain better material performance. <TEX>$Y_2O_3$</TEX> powders were prepared under a modified solvothermal condition involving precipitation from metal nitrates with aqueous ammonium hydroxide. The powders were obtained at temperatures at <TEX>$250^{\circ}C$</TEX> after a 6h process. The properties of the <TEX>$Y_2O_3$</TEX> powders were studied as a function of the solvent ratio. The synthesis of <TEX>$Y_2O_3$</TEX> crystalline particles is possible under a modified solvothermal condition in a water/ethylene glycol solution. Solvothermal processing condition parameters including the pH, reaction temperature and solvent ratio, have significant effects on the formation, phase component, morphology and particle size of yttria powders. Ethylene glycol is a versatile, widely used, inexpensive, and safe capping organic molecule for uniform nanoparticles besides as a solvent. The characterization of the synthesized Y2O3 powders were studied by XRD, SEM (FE-SEM) and TG/DSC. An X-ray diffraction analysis of the synthesized powders indicated the formation of the <TEX>$Y_2O_3$</TEX> cubic structure upon calcination. The average crystalline sizes and distribution of the synthesized <TEX>$Y_2O_3$</TEX> powders was less than 2 um and broad, respectively. The synthesized particles were spherical and hexagonal in shape. The morphology of the synthesized powders changed with the water and ethylene glycol ratio. The average size and shape of the synthesized particles could be controlled by adjusting the solvent ratio.

Wet ammonia Synthesis of Semiconducting N:Ta2O5, Ta3N5 and β-TaON Films for Photoanode Applications

Tantalum oxynitride (β-TaON) is a promising photoanode material for photoelectrochemical water splitting. However, the synthesis of phase-pure β-TaON films is a challenging task. This paper describes a novel approach to achieve this by the controlled nitridation of Ta2O5 films under a flow of ammonia gas (ammonolysis), which was obtained by bubbling argon through an aqueous ammonium hydroxide solution followed by a 5Å molecular sieve to remove the water. Depending on the nitridation conditions, either nitrogen-doped Ta2O5 or Ta3N5 was obtained as a thermodynamically stable phase. The evolution of the nitridation process was monitored in-situ using optical transmission spectroscopy, which revealed that the transformation of Ta2O5 to Ta3N5 occurred within minutes, through a series of intermediate oxynitride phases. This suggested the possibility of synthesizing the desired β-TaON phase by quenching the sample at the right time during the nitridation process. By choosing the right ammonolysis conditions (750°C, flow rate 50ml/min.), we were able to slow down the nitridation process and terminate it before the oxide was fully converted to Ta3N5. A post-nitridation heat treatment at 800°C indeed resulted in the formation of the desired β-TaON phase.

Chromatographic fingerprint analysis of yohimbe bark and related dietary supplements using UHPLC/UV/MS

A practical ultra high-performance liquid chromatography (UHPLC) method was developed for fingerprint analysis of and determination of yohimbine in yohimbe barks and related dietary supplements. Good separation was achieved using a Waters Acquity BEH C 18 column with gradient elution using 0.1% (v/v) aqueous ammonium hydroxide and 0.1% ammonium hydroxide in methanol as the mobile phases. The study is the first reported chromatographic method that separates corynanthine from yohimbine in yohimbe bark extract. The chromatographic fingerprint analysis was applied to the analysis of 18 yohimbe commercial dietary supplement samples. Quantitation of yohimbine, the traditional method for analysis of yohimbe barks, were also performed to evaluate the results of the fingerprint analysis. Wide variability was observed in fingerprints and yohimbine content among yohimbe dietary supplement samples. For most of the dietary supplements, the yohimbine content was not consistent with the label claims.

Synthesis and Biological Screening of 4-Benzyl-2H-phthalazine Derivatives

Preparation of 4-benzyl-2-substituted phthalazin-1-one derivatives 2-8 is reported. Condensation of 4-benzyl-1-chlorophthalazine (9) with a series of different nucleophiles gave 4-benzylphthalazin-1-ylamino derivatives (10-13 and 16) and 4-amino-2-[N′-(4-benzylphthalazin-1-yl)-hydrazino]-6-arylpyrimidine-5-carbonitriles (14a,b). Interaction of 9 with ambident anions was also studied. 5-Benzyl-6,6a,12-triazobenzo[a]-anthracen-7-one (15) is obtained from 9 and anthranilic acid derivatives. Treatment of 16 with (EtO)3CH/Ac2O under reflux afforded the corresponding ethoxymethylene derivative 17, while aqueous ammonium hydroxide treatment afforded carboxamide derivative 18. The structures of the newly synthesized derivatives were confirmed by their elemental analysis, IR, 1H NMR, 13C NMR and mass spectral studies. Antimicrobial activities of some selected compounds were also studied and some of these were found to exhibit promising effects against Gram-positive and Gram-negative bacteria and fungi.