The hydrophilic interaction like properties of some reversed phase high performance liquid chromatography columns in the analysis of basic compounds

The hydrophilic interaction chromatography (HILIC) like properties of an ACE cyano (CN) HPLC column was studied for the separation of some basic compounds. Good separation of a test mix of basic compounds was obtained with a mobile phase consisting of acetonitrile/water (95:5) containing 3.25 mM ammonium acetate. The retention times of the basic compounds decreased with increased ionic strength or with increased water content in the mobile phase. When Trishydroxymethyl aminomethane (Tris) (pK(a) 8.0), which is a weaker amine than ammonia (pK(a) 9.3), was used as an additive in the mobile phase retention of the basic compounds was increased. The ACE CN column gave excellent peak shapes for all the basic compounds. The utility of the column for impurity profiling of two basic drugs was tested and some impurities in oxprenolol were characterised by interfacing with Fourier transform mass spectrometry. It was also observed that ACE butyl and ACE phenyl columns retained basic compounds when the columns were eluted with a mobile phase consisting of acetonitrile/water (95:5) containing 3.25 mM ammonium acetate.     

A novel sensor for simultaneous determination of dopamine and uric acid using a new MFI-type zeolite prepared by microwave-assisted synthesis

Abstract  

This paper describes microwave-assisted synthesis of a new MFI-type zeolite, Zeolite Secony Mobile (ZSM-5), its characterization by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), and its application for fabrication of a modified carbon paste electrode. This novel electrode was employed for sensitive and simultaneous determination of dopamine and uric acid at biological pH (pH 7.0). The results show that this zeolite-modified carbon paste electrode significantly improves the electron transfer rate and reduces the overpotential of dopamine and uric acid oxidation without any fouling effect due to deposition of their oxidized products. The linear analytical curves were obtained in the ranges of 9.0 × 10⁻⁶–4.9 × 10⁻⁴ and 8.0 × 10⁻⁶–9.0 × 10⁻⁴ M for dopamine and uric acid, respectively, by using differential pulse voltammetry based on oxidation of these biomolecules. The detection limits (2σ) were determined for dopamine and uric acid as 7.9 × 10⁻⁶ and 7.1 × 10⁻⁶ M, respectively. This method has been successfully employed for quantification of dopamine and uric acid in real samples.     

Description of 160Dy nucleus by partial dynamical SU(3) symmetry

We considered the characteristic features of SU(3) partial dynamical symmetry in the interacting boson model framework to show the relevance of such intermediate symmetry structure in the nuclear spectroscopy of the ¹⁶⁰Dy nucleus. The predictions of SU(3)-PDS for the energy spectrum and the transition probabilities were compared with the most recent experimental data and an acceptable degree of agreement was achieved.     

The Effect of Epoxidized Natural Rubber and Two Kinds of Organoclay upon Molecular Interaction,Structure and Mechanical Properties of (Styrene-Butadiene Rubber/Acrylonitrile-Butadiene Rubber/Organoclay) Nanocomposites

Epoxidized natural rubber (ENR50) and two different kinds of organoclay (C30B and C15A) were used in blends of styrene-butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) and their effects upon interaction between phases, morphology, and mechanical properties of the blends were investigated. The compounds were characterized by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and differential scanning calorimetry (DSC). The obtained results showed formation of hydrogen bonding between the compounds ingredients due to incorporation of C30B, especially in presence of ENR. AFM and FE-SEM analysis revealed good dispersion of the nanoparticles in the polymer matrix upon addition of ENR as well as better dispersion of C30B than C15A in the NBR phase. XRD results showed a greater expansion of the silicate layers by simultaneous use of organoclay and ENR Incorporation of organoclay alone or in combination with ENR in the blends caused shifting of the SBR T_g toward the NBR T_g. The tensile properties of the blends showed improvement by using nanoparticles in the presence of ENR.     

Phytochemical components,total phenol and mineral contents and antioxidant activity of six major medicinal plants from Rayen,Iran

The aim of this work was to evaluate the phytochemical components, minerals, the antioxidant activity and total phenol contents of the essential oil from aerial parts of six major medicinal plants in Rayen, Iran. The plants included Ranunculus arvensis, Teucrium polium, Dracocephalum polychaetum, Kelussia odoratissima, Artemisia sieberi and Thymus kotschyanus. Total phenol content ranged from 0.03 to 0.158 mg/mL. A. sieberi showed the highest radical scavenging ability (IC₅₀ = 94 μg/mL). The amount of minerals ranged as follows: P (0.23–29%), K (1.08–4.76%), Ca (0.78–2.35%), Mg (0.24–0.94%), Cu (8.3–15 mg/kg), Cd (0.7–1.1 mg/kg), Pb (2–11.7 mg/kg) and Fe (250–1280 mg/kg). A total of 79 compounds were identified across all plants. The main components studied in the plants were l-perillaldehyde, biosol, carvacrol, 1,8-cineol, terpinyl acetate and 1,2,3,6,7,7 a-hexahydro-5 h-inden 5-one.     

A novel chemically modified carbon paste electrode based on a new mercury(II) complex for selective potentiometric determination of bromide ion

A new modified carbon paste electrode based on a recently synthesized mercury (II) complex of a pyridine containing proton transfer compound as a suitable carrier for Br⁻ ion is described. The electrode has a linear dynamic range between 3.00×10⁻² and 1.0×10⁻⁵ M with a near-Nernastian slope of 61.0±0.9 mV per decade and a detection limit of 4.0×10⁻⁶ M (0.32 ppm). The potentiometric response is independent of the pH of the solution in the pH range 4.0–8.3. The electrode possesses the advantages of low resistance, fast response and good over a variety of other anions. It was applied as an indicator electrode in potentiometric titration of bromide ions and for the recovery of Br⁻ from tap water.     

Some aspects of stability of multiple emulsions in personal cleansing systems

The two dominant factors that were found to affect the stability of multiple emulsions in high HLB surfactant systems are the osmotic pressure imbalance between the internal aqueous phase and the external aqueous phase, and the adsorption/desorption characteristics of the emulsifier/surfactant film at the oil/water interface. Synergistic interaction between the low HLB emulsifier and the high HLB surfactant that produces very low interfacial tension of the order of 10(-2) mN/m at the oil/water interface was found to occur in some of the systems investigated. Long term stability was observed in multiple emulsion containing these systems. However, no synergy was observed in systems in which either the oil or the emulsifier, or both, contained unsaturated chains. In fact, desorption of the adsorbed surfactant film was observed in systems containing unsaturated chains. The observed desorption from the interface of the emulsifier in these systems was attributed mainly to the inability of the unsaturated chains to form a close packed, condensed interfacial film. Presence of closely packed, condensed interfacial film is necessary to prevent solubilization of the adsorbed low HLB emulsifier by the high HLB surfactant. Multiple emulsions prepared using systems containing unsaturated hydrocarbons were highly unstable.     

Promotion of Improved Discrete Polynomial-Phase Transform Method for Phase Parameters Estimation of Linear Frequency Modulation Signal

Journal of Communications Technology and Electronics - The discrete polynomial-phase transform (DPT) method estimate chirp rate and central frequency of LFM signal based on sequential estimation of...