Search results for "Osmolar Concentration"
showing 10 items of 106 documents
Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas…
2013
Abstract A new analytical method based on simultaneous derivatization and dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography–mass spectrometry (GC–MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC–MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid–liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample …
Determination of organophosphorus pesticides in honeybees after solid-phase microextraction.
2001
A method based on solid-phase microextraction (SPME) followed by gas chromatography with nitrogen-phosphorus detection was developed for the purpose of determining 18 organophosphorus pesticide residues in honeybee samples (Apis mellifera). The extraction capacities of polyacrylate and poly(dimethylsiloxane) fibers were compared. The main factors affecting the SPME process, such as the absorption time profile, salt, and temperature, were optimized. The method involved honeybee sample homogenization, elution with an acetone:water solution (1:1) and dilution in water prior to fiber extraction. Moreover, the matrix effect on the extraction was evaluated. In samples spiked at the 0.2 mg kg(-1) …
Development of stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles and its analytical application to the determination of…
2014
A novel microextraction technique combining the principles of stir bar sorptive extraction (SBSE) and dispersive micro-solid phase extraction (DμSPE) is presented. The main feature of the method is the use of a neodymium-core stirring bar physically coated with a hydrophobic magnetic nanosorbent. Depending on stirring speed, the magnetic sorbent either acts as a coating material to the stir bar, thus affording extraction alike SBSE, or as a dispersed nanosorbent medium for the collection and extraction of the target analytes, in close analogy to DμSPE. Once the stirring process is finished, the strong magnetic field of the stir bar prevails again and rapidly retrieves the dispersed MNPs. Al…
Subcutaneous Injection of Drugs: Literature Review of Factors Influencing Pain Sensation at the Injection Site.
2019
The subcutaneous administration route is widely used to administer different types of drugs given its high bioavailability and rapid onset of action. However, the sensation of pain at the injection site might reduce patient adherence. Apart from a direct effect of the drug itself, several factors can influence the sensation of pain: needle features, injection site, volume injected, injection speed, osmolality, viscosity and pH of formulation, as well as the kind of excipients employed, including buffers and preservatives. Short and thin needles, conveniently lubricated and with sharp tips, are generally used to minimize pain, although the anatomic injection site (abdomen versus thigh) also …
Shape transitions of giant liposomes induced by an anisotropic spontaneous curvature
2000
International audience; We explore how a magnetic field breaks the symmetry of an initially spherical giant liposome filled with a magnetic colloid. The condition of rotational symmetry along the field axis leads either to a prolate or to an oblate ellipsoid. We demonstrate that an electrostatic interaction between the nanoparticles and the membrane triggers the shape transition. PACS numbers: 75.
Seminal plasma biochemistry and spermatozoa characteristics of Atlantic cod (Gadus morhua L.) of wild and cultivated origin
2011
Abstract Our objectives were to compare spermatozoa activity, morphology, and seminal plasma (SP) biochemistry between wild and cultivated Atlantic cod ( Gadus morhua ). Swimming velocities of wild cod spermatozoa were significantly faster than those of cultivated males. Wild males had a significantly larger spermatozoa head area, perimeter, and length, while cultivated males had more circular heads. Total monounsaturated fatty acids and the ratio of n−3/n−6 were significantly higher in sperm from wild males, while total n−6 from cultivated males was significantly higher than the wild males. Significantly higher concentrations of the fatty acids C14:0, C16:1n−7, C18:4n−3, C20:1n−11, C20:1n−…
Bio-predictive tablet disintegration: Effect of water diffusivity, fluid flow, food composition and test conditions
2013
Abstract Food intake may delay tablet disintegration. Current in vitro methods have little predictive potential to account for such effects. The effect of a variety of factors on the disintegration of immediate release tablets in the gastrointestinal tract has been identified. They include viscosity of the media, precipitation of food constituents on the surface of the tablet and reduction of water diffusivity in the media as well as changes in the hydrodynamics in the surrounding media of the solid dosage form. In order to improve the predictability of food affecting the disintegration of a dosage form, tablet disintegration in various types of a liquefied meal has been studied under stati…
Interaction of sodium, lithium, caesium, and potassium ions with ascorbyl radicals.
1987
Abstract The influence of the concentration of sodium, lithium , caesium, and potassium ions as well as of the ionic strength of the solutions used on the dismutation rate of ascorbyl radicals has been investigated. While the dismutation rate was not influenced by Li+, it decreased, however, with increasing concentrations of the other ions investigated. The largest effect was obtained with Na+. This change in dismutation rate indicates a stabilizing effect on ascorbyl radical by these ions.
Acanthamoeba isolates belonging to T1, T2, T3, T4 and T7 genotypes from environmental freshwater samples in the Nile Delta region, Egypt.
2006
The free-living amoebae of the genus Acanthamoeba include non-pathogenic and pathogenic species and has been recently classified into 15 different genotypes, T1–T15. In this study, a survey was conducted in order to determine the presence and pathogenic potential of free-living amoebae of Acanthamoeba genus in freshwater sources associated with human activities in the Nile Delta region, Egypt. Identification of Acanthamoeba was based on the morphology of cyst and trophozoite forms and PCR amplification with a genus specific primer pair. The pathogenic potential of Acanthamoeba isolates was characterized using temperature and osmotolerance assays and PCR reactions with two primer pairs speci…
Expanding the application of stir bar sorptive-dispersive microextraction approach to solid matrices: Determination of ultraviolet filters in coastal…
2018
This work describes a new method for the determination of organic compounds in solid samples based on the equilibrium desorption of the analytes in an aqueous phase followed by stir bar sorptive-dispersive microextraction (SBSDME). Sand samples, contaminated with UV filters due to bathing and recreational activities, were dispersed in an aqueous medium by using a coated stir bar with CoFe2O4@oleic acid magnetic nanoparticles. The UV filters were physically desorbed from the surface of the sand particles and rapidly adsorbed on the hydrophobic coating of the nanoparticles, which were retrieved by means of their magnetism after stopping the stirring. In this manner, both preconcentration of t…