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Abstract  

The objective of this work was to develop and validate a fast and reproducible method which is able to determine the concentration of ketoconazole in raw materials and tablets. The samples were analyzed by dynamic thermogravimetry at heating rates of 10, 20, 40, 60 and 80°C min−1 in nitrogen and nitrogen-synthetic air mixture. The concentrations of ketoconazole in the raw material and in the tablets were obtained from the vapor pressure curves. The data showed that there is no significant difference between the vapor pressure profiles of ketoconazole itself and in its tablet in both studied environmental conditions confirming that the process is really vaporization. The concentration of ketoconazole was determined in the raw material and tablets of the drug.

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Abstract  

The authors have measured the vapour pressure of four binary systems, morpholine+piperidine, morpholine+1,4-dioxane, morpholine+tetrahydropyrane and 1,4-dioxane+tetrahydropyrane. The measurements were carried out using an isoteniscope built by J. Jose [1]. The vapour pressure, excess Gibbs free energies at 298.15, 303.15, 313.15, 323.15, 333.15 and 343.15 K are reported for these mixtures. The excess Gibbs free energies have been fitted to the Redlich-Kister equation.

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Abstract  

The objective of this work was to develop and validate a fast and reproducible method able to determine the concentration of mebendazole in raw materials and tablets. The samples were analyzed by dynamic thermogravimetry, in the heating rates of 10, 20, 40, 60 and 80C min–1, in the atmospheres of nitrogen and nitrogen with synthetic air. Obtained data were used in the equations of Antoine and Langmuir, with the purpose to get the pressure curves of those. Vapor pressure curves of drug and tablet of mebendazole were evaluated using the mathematical indexes of difference factor, f 1, and similarity factor, f 2, to compare its profiles. The data showed that there is no significant difference between the vapor pressure profiles of drug and tablet of mebendazole in both environmental conditions studied, what confirms that the process is really vaporization. The concentration of mebendazole was determined in the raw material and tablets with the drug.

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The thermogravimetric curve (TG) for the decomposition of carnallite (KCl · MgCl2 · 6H2O) at constant water vapor pressure (1 bar) was calculated from the phase diagram (solid-liquid equilibria) and vapor pressure data, and the calculated and experimental results were compared.

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Journal of Thermal Analysis and Calorimetry
Authors: Ksenia Zherikova, Natalia Morozova, Ludmila Zelenina, S. Sysoev, Tamara Chusova, and I. Igumenov

Abstract  

Five volatile hafnium(IV) and zirconium(IV) β-diketonates: hafnium(IV) acetylacetonate, hafnium(IV) trifluoroacetylacetonate, hafnium(IV) pivaloyltrifluoroacetonate, hafnium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate and zirconium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate were obtained, purified and identified. Thermal behavior of solid compounds was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC) in helium atmosphere and in vacuum. DSC method was also used for definition of thermodynamic characteristics of melting processes. Using the static method with quartz membrane zero-manometer and the flow method the temperature dependencies of saturated vapor pressure for hafnium(IV) complexes was obtained. The standard thermodynamic characteristics ΔH T 0 and ΔS T 0 of sublimation and evaporation processes were calculated from the temperature dependences of saturated vapor pressure.

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Abstract  

The objective of this work was to develop and validate a fast and reproducible method to determine the concentration of metronidazole in drug substance and tablets. The samples were analyzed by dynamic thermogravimetry, using 10, 20, 40, 60 and 80C min–1 heating rates in nitrogen and in nitrogen with synthetic air. Obtained data were used in the Antoine and Langmuir equations in order to have the pressure curves. Vapor pressure curves of drug and tablet of metronidazole were evaluated using the mathematical indexes of difference factor, f 1, and similarity factor, f 2, to compare their profiles. The data showed that there is no significant difference between the vapor pressure profiles of drug and tablet of metronidazole in both environmental conditions, which confirms that the process is really vaporization. The concentration of metronidazole was determined in the raw material and tablets of the drug.

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Abstract  

Radiochemical technique was used to investigate cryogenic chemical reaction. By introducing reactants of H and T into liquid 3H through 3He(n,p)T reaction, behaviors of H+T→HT and T+T→T2 were investigated under pressurized condition. Within saturated vapor pressure upto 0.61 Mpa, the isotope ratio of HT/T2 changed. It was suggested that the change of HT/T2 was attributed to bubble formation and chemical potential in liquid helium.

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Abstract  

A bipolar electrolysis system for tritium accumulation and HTO waste volume reduction was designed and built. Experiments were performed to achieve the system specific separation factor for iron and stainless steel cathodes in a 1M sodium hydroxide solution. A separation factor of about 6 for stainless steel and 19 to 26 for iron was measured. The vapor pressure isotope effect under experimental conditions was determined as 1.09±0.03 (T = 279 K).

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Abstract  

This work is dealing with grafting of poly-propylene fibres /POP/ prepared by the pre-irradiation technique. A hydrophility change in irradited and modified samples was studied. Irradiation was performed in a chamber type RCH-gamma-30 radiation equipment, containing60Co. In the radiation modified samples of POP fibres prepared by the preirradiation technique the humidity adsorption increased from 0.1% to 0.56% after the radiation dose of 24.5 kGy has been used. The sorption properties of the samples were studied on McBeen balances with regard to temperature and water-vapour pressure.

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Summary  

Tritium exchange and enrichment was studied for several different metal salts, e.g., AlF3 . H2O, FeO(OH), CsI, CsF, NaI, NaF and Al(OH)3 using a cryosublimation apparatus. Experiments were performed below equilibrium vapor pressure to avoid any isotope effects. A comparable tritium enrichment factor of 1.14 to 1.43 was obtained for all systems, except for CsF, which gave an enrichment factor of 1.93. These results confirm the concept, that 3H is accumulated in weak hydrogen bonds as already observed in organic molecules.

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