Authors:Kate Poiesz, Carol Grundner, and Nancy Redman-Furey
Characterization of the solid-state form (hydrate
or polymorph) of a pharmaceutical active is a key scientific and regulatory
requirement during development of and prior to seeking approval for marketing
of the drug product. A variety of analytical methods are available to perform
this task. By nature of the fundamental information it provides, TG-DTA offers
advantages over other methods in regards to monitoring and quantitation of
hydration state changes. In a single experiment with only a few milligrams
of sample, TG-DTA perceives minor changes in phase, quantitates total water
content and percent conversion, and illustrates hydrate type. All of this
is accomplished without the necessity of generating time-consuming standard
curves representing the differing ratios of hydrated to anhydrous forms. This
study describes the use of TG-DTA to monitor and quantitate humidity induced
solid–solid phase conversion of nitrofurantoin and risedronate. Percent
conversion was qualitatively observed by both TG and DTA signals and quantitated
by the TG.
Authors:L. Chen, W. Song, J. Lv, L. Wang, and C. Xie
Aluminum (Al) nanopowders with mean diameter of about 50 nm and passivated by alumina (Al2O3) coatings were prepared by an evaporation route: laser heating evaporation. Thermal properties of the nanopowders were investigated
by simultaneous thermogravimetric-differential thermal analysis (TG-DTA) in dry oxygen environment, using a series of heating
rates (5, 10, 20, 30, 50 and 90°C min−1) from room temperature to 1200°C. With the heating rates rise, the onset and peak temperatures of the oxidation rise, and
the conversion degree of Al to Al2O3 varies. However, the specific heat release keeps relatively invariant and has an average value of 18.1 kJ g−1. So the specific heat release is the intrinsic characteristic of Al nanopowders, which can represent the ability of energy
Authors:D Montecchio, O Francioso, P Carletti, D Pizzeghello, S Chersich, F Previtali, and S Nardi
acids (HAs) extracted from soils developed under two Norwegian spruce (Picea
abies, (L.) Karst) subalpine forests of northern Italy were characterized
using chemical, thermal (TG-DTA) and spectroscopic (DRIFT) analyses. The samples
were taken from five sites which differed in orientation (northern and southern
exposure) and vegetal cover at different old age: grassland, regeneration,
immature and mature stands. In general, the thermal patterns of HAs were similar
(three exothermic reactions appeared around at 300, 400 and 500C) in
both sites in grasslands and regeneration while a considerable modification
appeared in HA from stands of different age at northern and southern exposure
site. DRIFT spectroscopy confirmed the differences observed through TG-DTA
analysis. In particular the main structural changes were ascribed to modification
of carbonyl group and of CH stretching in aliphatic components in each HAs
from different sites.
Authors:XiuYan Wang, JieMin Liu, QiShan Yang, Jian Du, FengE Wang, and Wu Tao
weight and enthalpy during reaction were obvious [ 10 – 15 ].
In this paper, the thermogravimetry–differential thermal analysis (TG–DTA) and Fourier transform infrared spectroscopy (FTIR) were used to real time monitor the reaction process of
Newly developed coupling systems are introduced and discussed for the combination of a simultaneous TG-DTA apparatus with a quadrupole mass-spectrometer. In the study of decomposition processes under atmospheric pressure, two-stage pressure reduction systems allow an exact gas analysis by the simultaneous operation of a mass-spectrometer up to 1550‡. For measurements under high vacuum, the pressure reduction systems are removed, and by direct viewing between test body and ion source a high sensitivity is achieved. The function of these combined units is demonstrated by means of applications in inorganic and organic chemistry.
Authors:K. Siimer, P. Christjanson, T. Kaljuvee, T. Pehk, I. Lasn, and I. Saks
The thermal behaviour of MUF resins from different suppliers with different content of melamine was studied, along with the
13C NMR spectroscopic analysis of resin structure and the testing of particleboards in current production at Estonian PB factory
Pärnu Plaaditehas AS. The chemical structure of resins from DMSO-d6 solutions was analysed by 13C NMR spectroscopy on a Bruker AMX500 NMR spectrometer. The melamine level in different MUF resins is compared by the ratios
of carbonyl carbon of urea and triazine carbon of melamine in 13C NMR spectra. Curing behaviour of MUF resins was studied by stimultaneous TG-DTA techniques on the Labsys™ instrument Setaram.
The shape of DTA curves characterisises the resin synthesis procedure by the extent of polymerisation of UF and MF components
and is in accordance with structural data.
Authors:M. Anastasiou, Th. Hasapis, T. Zorba, E. Pavlidou, K. Chrissafis, and K. Paraskevopoulos
plasters from wall paintings of Byzantine and post-Byzantine churches situated
in the Balkan region were studied. All wall paintings were made with fresco
technique and are dated from IX - XVI century. Plaster samples were followed
from room temperature to 1000C by Thermogravimetric (TG) and Differential
Thermal Analysis (DTA), and one or two significant temperature regions, corresponding
to thermal decomposition mechanisms were observed. The analysis of the plaster
samples and the composition characterization was carried out using also, Fourier
Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM).
Although the main components are calcite and quartz (from sand) in different
proportions, there are differences between them such as the presence of gypsum
being either as a constituent element or due to environmental pollution. The
results are examined comparatively taking into account the creation time and
place of the paintings.
Authors:R. Kinoshita, Y. Teramoto, T. Nakano, and H. Yoshida
A combination system of thermogravimetric/differential thermal analysis (TG-DTA) and Fourier-transform infrared absorption spectroscopy (FT-IR) was described. This simultaneous TG-DTA/FT-IR technique gave spectroscopic and weight loss information about the thermal degradation process of engineering polyesters; poly(ethylene terephthalate)(PET) and poly(butylene terephthalate)(PBT). The evolved gases from PET were benzoic acid, carbon dioxide and carbon monoxide, while those from PBT were terephthalic acid esters and benzoic acid esters.
Authors:R. Ozao, T. Okabe, T. Arii, Y. Nishimoto, Y. Cao, N. Whitely, and W.-P. Pan
Summary An odorless woodceramics (CH800), which was prepared by carbonizing chicken wastes with phenolic resin, was characterized by XRD and thermal analysis. CH800 was found to consist mainly of amorphous carbon (non-graphitizing carbon) as studied by XRD. Differing from carbonized chicken waste, CH800 was completely free of unfavorable smell. The source of strong smell of carbonized chicken waste was studied by using TG-DTA combined with EGA technique using gas chromatography and mass spectrometry (TG-DTA/GC-MS). As a result, it was found that CH800 was completely free of compounds having strong smell, i.e., ethanol, acetonitrile, pyridine, styrene, benzonitrile and benzofuran, whereas carbonized chicken waste contained all of these compounds.