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
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.
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: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.
To improve the separation of the dihydrate and hemihydrate phases, different sample masses, heating rates and crucibles were used. A TG-DTA method was developed for the determination of water evolved from CaSO4·xH2O. The new crucible introduced for the Q-1500D MOM derivatograph gives a possibility for the evolved water to be determined independently from the TG and DTA curves.
Authors:G. Madhurambal, M. Mariappan, and S. Mojumdar
A mixed crystal of urea–thiourea was grown by slow evaporation of aqueous solution at room temperature. The bright and transparent
crystals obtained were characterized by thermogravimetric–differential thermal analysis (TG–DTA), UV and FTIR spectroscopic
analyses. A fitting decomposition pattern for the title compound was formulated on the TG curve which shows a two stage weight
loss between 200 and 750 °C. In this temperature range DTA curve shows exothermic peaks supporting the formulated decomposition
pattern. The UV and FTIR spectra show the characteristic absorption, vibration frequencies due to urea–thiourea mixed crystals.
Detailed structural analysis of the compound is under progress.
Authors:Carol Grundner, Kate Poiesz, and Nancy Redman-Furey
The successful combination of microscopy with thermogravimetry-differential
thermal analysis is reported. Simultaneous use of all three techniques is
made possible by custom fitting a quartz glass window into the furnace of
a commercially available TG-DTA. The quartz window enabled direct observations
from a microscope mounted above the furnace throughout the entirety of the
thermal analytical experiments. Several examples are provided for the use
of this combined system for evaluating dehydrations, degradation and phase
conversions in pharmaceutical materials. In some examples, microscopy provided
information not accessible from the thermal analytical data alone. In others,
the thermal analytical data was more informative than the microscopy.