Analogy of thermogravimetric measurements

Dimensionless number has been developed and introduced for quantitative analysis of the effect of thermogravimetric measuring factors like sample quantity, heating rate, etc. The TG, DTG and T data of different thermogravimetric measurements can be used directly for calculation of the three constants of analogy. TG data of CaCO₃ measured in very different conditions show the method of transformation and its applicability for calculation of the correlation of measurements.     

Error Levels of Different Methods of Evaluation of TG Measurements

It follows from an analysis of the error levels of TG evaluation methods that it is a conceptual error to disregard the analogies of mass, energy and momentum streams of subordinate partial processes. This error is bypassed by means of the introduced method of dimensionless analysis and by determining the characteristic, constants-like data of thermal processes by using the measured data directly. These methods are very suitable for increasing the consistency of the calculated results by seeking for similarity, even in comparisons of measurements made under very different conditions and for emphasizing the differences too, quantitatively. With this new interpretation of TG processes, the idea of the kinetic compensation effect becomes only a consequence of the discussed conceptual error. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal analysis of some fly ashes

The self-hardening activity of fly ashes was investigated looking for the possibility of their chemical reactions with water without additives. A method had to be developed for separation of the structural water from the adsorbed or free one. The decomposition of the chemically bound water was measured by thermogravimetry. The‘I’ dimensionless number proved to be applicable for the quantitative characterisation of the measured data with more DTG peaks. The examined reaction depends on the chemical composition and the physical structure of the fly ashes and the time of interaction with water. The SO₃ content seems important, but the characteristics of the formed compounds differ deeply from the CaSO₄·2H₂O. The observed and examined reaction is an important factor of the self-hardening process of fly ash deposits.     

Extending the applicability of TG measurements to industry and to quality ensuring by dimensionless analysis

TheI _i=E _i/RT _i dimensionless evaluation is very suitable for describing the TG measurements according to theE _i/RT _i=lnA +n[ln(1–)_i]–ln(d/dr)_i equation. TheI _i andE _i functions make the comparison of the different TG measurements possible quantitatively in the case of more DTG peaks as well.TheI _i andE _i values as function of (1-)_i and 1/T _i open new way for further theoretical and practical studies by TG measurements. Such types of results are the quantitative determination of the effect of the measuring conditions, the measuring of the mechanochemical effect of grinding and among others the explanation of the self-hardening process of fly ashes of power stations.Strict connections exist between theI _i functions and the constants of the compensation effect (CE). These constants (tan, axis intersect) can be calculated directly from the average of the measured data of theI _i function making the introduction and theoretical and practical application of the idea of general activation energy (¯E) possible. The quantitative characterisation of the examined materials of the fine structure ofCE and of the thermal processes together proves the extending importance of TG measurements from industrial and material qualification aspects as well.The author thanks gratefully to Professor Márta Fehér mathematicien, Head of the Department of Philosophy at the Technical University of Budapest for the consultations and for the encouragements.     

Development of incurred reference material for improving conditions of gluten quantification

Celiac disease and wheat allergy are the most common adverse reactions triggered by cereal proteins, mainly gluten, which is one of the 14 allergenic food ingredients that must be labeled on food products in the European Union (EU). To meet the requirements of this regulation, reliable analytical methodology for proper quantification of gluten is necessary. However, validation of presently used methods (ELISA and lateral flow device) is limited partly due to the lack of reference methods and incurred reference materials. To solve this problem, the goal of our work was to develop an incurred reference material for the quantification of gluten under the auspices of EU-FP6 funded Network of Excellence MoniQA. During this work, we produced a processed model product (cookie) containing gliadin (major allergenic fraction of gluten) in a defined amount. This paper addresses the development process of this material together with the associated problems (insufficient homogeneity and low recovery) and their solutions. As a result, an incurred food matrix was produced on a laboratory-scale with a potential use as a reference material. The model product was tested by an ELISA method followed by a comparative study of commercially available ELISA kits to investigate the applicability of the product. Preliminary results of this study are also presented.     

Evaporation Analogies Between Light Hydrocarbons Effect of Molecular Mass of Purge gas

The evaporation of benzene, cyclohexane, n-heptane, toluene, 2-xylene, 3-xylene and 4-xylene was studied in H₂, He, N₂ or CO₂ as purge gases for control of the introduced methods of evaluation and the sensitivity limits of TG measurements. I_i as a function of (1−α) and the following equation proved very suitable for a quantitative comparison of 28 independent and different TG measurements and for a very sensitive characterization of the thermal processes, even within an energy level difference of 3 kJ mol⁻¹, in spite of the known great inconsistency in the formal kinetic parameters: