A rapid HPIC method for the quantitative determination of tetramethylammonium chloride in some aqueous solutions used as food simulants

Summary The present paper reports a rapid HPIC method for the determination of tetramethylammonium chloride in aqueous matrices which are used as food simulants in migration tests. These simulants were: bidistilled water, an aqueous solution of 3% acetic acid, an aqueous solution of 15% ethyl alcohol, a mixed aqueous solution of 3% acetic acid and 15% ethyl alcohol. The method, as developed, has been applied to the determination of unreacted tetramethylammonium chloride residues which are able to migrate from finished epoxy resins which are used as food packaging materials.Research partially supported by National Research Council of Italy, Special Project RAISA, sub-project 4, Paper N^o 695.     

Morphological and Spectral Characteristics of Hybrid Nanosystems Based on Mono- and Bimetallic Platinum Nanoparticles and Silver

Russian Journal of Physical Chemistry A - Morphological and spectral characteristics of hybrid nanosystems (NSes) based on mono- and bimetallic silver and platinum nanoparticles (NPs) stabilized by...     

Effects of solubilized dodecylamine on the microstructure of cetylpyridinium bromide-<Emphasis Type="Italic">n</Emphasis>-butanol-hexane-water system studied by pulsed-gradient spin echo NMR and ESR spin label methods

The effect of solubilized dodecylamine (DDA) on the structure of the cetylpyridinium bromide-n-butanol-hexane-water microemulsions has been studied by the Fourier-transform pulsed-gradient spin-echo¹H nuclear magnetic resonance and the electron spin resonance spin label method. The sample compositions were chosen to examine three different microemulsion structures: oil-in-water, water-in-oil and bicontinuous. In all systems the DDA molecules are shown to be incorporated into the oil-water interface, resulting in essential changes in the microemulsion structure. In the micellar systems the DDA emergence in the interface causes an increase of the micelle size and a redistribution of butanol and water between micelle and bulk phases. In the oil-in-water microemulsions of amine-containing systems the quantity of micellized butanol and water decreases. In the water-in-oil microemulsions the introduction of DDA leads to an increase of butanol and water involved in the micelle formation. The redistribution of butanol and water between polar and organic phases in the microemulsions would be expected to cause changes in the bicontinuous structure.     

Morphology and thermodynamic characteristics of selenium-containing nanostructures based on polymethacrylic acid

The morphology and thermodynamic characteristics of nanostructures formed as a result of the reduction of the selenium ion in a selenite-ascorbate redox system in water solutions of polymethacrylic acid were studied by molecular optics and atomic-force microscopy. The dependence of the morphology of the selenium-containing nanostructures on the mass selenium-to-polymer ratio (ν) in solution was determined. It was established that a large number of macromolecules (up to 4300) is adsorbed on the selenium nanoparticles, leading to the formation of nanostructures with super-high molecular mass and an almost spherical form. It was shown that the density of the nanostructures, as calculated on the basis of the experimental data on the size and molecular mass of the nanocomposite, depends substantially on the selenium concentrations in the solution. The thermodynamic state of the solutions of nanostructures is described.