Authors:Ana Gomes, Lidiane Correia, Mônica da Silva Simões, and R. Macêdo
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, f1,
and similarity factor, f2,
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.
Authors:Ana Gomes, Lidiane Correia, Mônica da Silva Simões, and Rui Macêdo
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, f1, and similarity factor, f2, 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.
Authors:F. Belaribi, G. Belaribi-Boukais, A. Ait-Kaci, and J. Jose
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 . 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.
A calorimetric method for the study of solid-vapor interactions is described. In one calorimetric chamber a vapor evaporates;
in a second calorimetric chamber the vapor is absorbed by a sample. The two chambers are connected by a tube and form part
of a double twin microcalorimeter. As vapor is sorbed by the sample the vapor pressure in the sorption chamber will increase
from a low value to near saturation. The flow rate of the vapor is governed by diffusion through the tube between the vessels.
From the thermal power measured in the vaporization calorimeter it is possible to evaluate the sorption isotherm, and using
information from both calorimeters the heat of sorption may be calculated as a function of equilibrium vapor pressure. By
conducting experiments with different sized samples it is also possible to study the kinetics of the sorption process. The
paper describes some recent improvements of the technique and gives examples of its use.
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.
Authors:Ksenia Zherikova, Natalia Morozova, Ludmila Zelenina, S. Sysoev, Tamara Chusova, and I. Igumenov
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
ΔHT0 and ΔST0 of sublimation and evaporation processes were calculated from the temperature dependences of saturated vapor pressure.
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.
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).
The present work reports the experimental determination of the standard (po = 0.1 MPa) molar enthalpies of formation in the condensed and gaseous phases, at T = 298.15 K, of 5- and 6-nitroindazole. These results were derived from the measurements of the standard molar energies of
combustion, using a static bomb calorimeter and from the standard molar enthalpies of sublimation derived by the application
of Clausius–Clapeyron to the temperature dependence of the vapour pressures measured by the Knudsen effusion technique. The
results are interpreted in terms of the energetic contributions of the nitro groups in the different positions of the aromatic
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.