In this paper the temperature calibration of a Mettler Toledo DSC27HP high-pressure DSC for measurements in an ammonia atmosphere
is described. Measurements were performed on the melting process of three reference substances in golden crucibles: indium,
tin and lead. The procedure described by the German Society for Thermal Analysis and Calorimetry, GEFTA, was applied: to correct
for temperature gradients in the DSC-cel extrapolated onset temperatures of the endothermic melting peaks were measured as
a function of heating rate to find by extrapolation the extrapolated onset temperature at zero heating rate, which should
be a temperature corrected for temperature gradients. However, measurements performed at different pressures (between 1.5
and 8.4 bar) showed that the evaluated extrapolated onset temperatures at zero heating rate decreased with increasing pressure.
This observation cannot be explained by the known dependence of melting temperatures on pressure. Therefore pressure dependence
of the extrapolated onset temperatures must be caused by experimental issues. It is assumed that, although the results were
extrapolated to zero heating rate, results are still influenced by temperature gradients in the DSC-cell. As a mean value,
the extrapolated onset temperatures at zero heating rate decreased by 0.053�C when the pressure was raised by 1 bar. Since
the software package does not allow for the pressure dependence of calibration parameters, measurement results must be corrected
manually for this effect.
Authors:A. Marini, V. Berbenni, G. Bruni, A. Maggioni, and M. Villa
The heat capacity calibration ‘constants’ of a commercial MTDSC system (TA 3100) were determined in a variety of experimental
conditions. For a given modulation frequency, the calibration constants are the same within a few percents for different temperatures,
and over a wide range of modulation amplitudes and scan rates. This variation decreases below 1% if hidden instrumental constraints
are taken into account, which are related with the capability of the control system to achieve the desired temperature program.
On the other hand, the calibration constant changes substantially with the period, and takes anomalously high values for the
short modulation periods (20+40 s). Rules to optimize the accuracy of the system are given.
The behaviour of Ni−Fe−Ni sandwich material was investigated in air atmosphere up to 850°C with the NETZSCH microbalance TG
209. The aim was to determine if this substance is suitable for calibration.
The results show that nickel-iron-nickel-bimetal makes it possible to calibrate thermobalances whilst expending a minimum
of time and effort.
Authors:István Buzás, E. Hoyk, I. Cserni, and J. Bors-Pető
It was found that quantitative and qualitative
indices of the sweet corn yield correlate with the nitrate nitrogen content of
the upper soil layer (0-30 cm). As no correlation was established between the
nitrate nitrogen content of the lower layers and the sweet corn, the conclusion
was drawn that the quantity of sweet corn yield is determined even before its
roots reach deeper down than 30 cm and the nitrogen content of the lower layers
could affect the sweet corn. Depending
on the NO
-N content of the soil before fertilization the maximal
corn ear mass achievable with fertilization may vary. In the study the same
yield could not be accomplished in the case of the lowest soil nitrogen
concentration (2.9 mg NO
-N/kg) with the highest fertilizer rate
(200 kg N/ha) - but probably irrespective of any amount of fertilizer - as on
the soil of 4.6 mg NO
-N/kg. In the case of the poorly supplied soil
the fertilization curve becomes flat sooner or turns negative. The phenomenon
that, regarding various soils, the maximal yield achievable on soils with good
production features with fertilization is higher than in the case of soils
having worse features, is well-known. That this fact is also valid in the case
of the same soils was expected after calibration experiments carried out with
winter oilseed rape and beet root, but it has not been proven for sweet corn as
yet. The results also showed that the
grain dry matter production of sweet corn per hectare can still be enhanced
with the increase in the soil's nitrogen supply, even if the corn ear does not
grow. The presented calibration curves
show - in the range of 2.9-4.6 mg NO
-N/kg soil - how much corn ear
and grain dry matter produce are expected on soils with differing nitrogen
supply, distributing 0-200 kg nitrogen fertilizer in spring.
Authors:G. De Domenico, D. Lister, G. Maschio, and A. Stassi
A simple method for the on-line calibration, in which both the heat transfer coefficient and the heat capacity of the reactor
contents are determined, is described for laboratory scale heat transfer calorimeters. The calorimeter is operated in the
isoperibolic mode for the calibration and a constant power is supplied to a resistor placed inside the reactor. The reactor
heat balance differential equation is used to produce a set of linear simultaneous equations with each data acquisition cycle
giving one equation. The heat transfer coefficient and the heat capacity are obtained from this set of equations by linear
least squares. The application of the calibration procedure is illustrated by experiments in which the heat of reaction is
determined on-line fora simulated reaction with first order kinetics and for the hydrolysis of acetic anhydride.
Micro-thermal analysis (μTATM) is a technique in which thermal analysis is performed on surfaces of test specimens on a small (ca. 2×2 μm) scale. Like
any thermal analysis technique, interpretation of results benefits from accurate temperature information and knowledge of
the precision of the resultant measurement. However, temperature calibration for such methods is more challenging than with
its macro relatives since the calibrant comes into direct contact with the AFM sensor. This paper describes suitable calibration
procedures for different types of transitions namely for first order transitions (melting points) and for glass transition
temperatures using organic chemicals and polymers.
adjust the outputs to evaluate the accuracy of a model's estimations. This process can be improved by narrowing down the most influential input parameters using statistical methods such as sensitivity analysis [ 10–12 ]. However, the calibration of
Several reference materials
and associated reference values have been recommended for the purposes of
calibration and/or validation of differential scanning calorimetry (DSC).
However, issues of available sample purity, reference-property value accuracy,
and potential undesired reactions between reference materials and the materials
used for sample pans have not been considered sufficiently in some of the
recommendations of property values for the materials. These limitations attenuate
greatly the usefulness of many of these reference material recommendations.
Indeed, the state of uncertainty regarding true reference property values
can be shown to be a limiting factor in the uncertainty of measurements made
with DSC. NIST has certified the temperatures and enthalpies of fusion of
two new Standard Reference Materials, SRMs 2234 and 2235, in order to help
alleviate some of the difficulty.
Authors:Beata Salamon, Jan Kapała, and Marcelle Gaune-Escard
pure for analysis), PrBr 3 was prepared before [ 2 ]. The metallic gallium (Aldrich 99.99% trace metals basis) was used as a reference material. The calibration of thermocouple were done for two temperature points: melting point of water and melting
A number of compounds are investigated for DSC calibration during cooling. Adamantane and Zn show fast reversible transitions
and can be applied both for temperature and for heat calibration. A third compound, namely 4,4′-azoxyanisole, has a liquid
crystal to isotropic liquid transition at 409 K. This compound can be used for temperature calibration. Heat calibration with
this compound is more problematic because of the small heat effect and the construction of the baseline. Two other compounds,
namely Hg and Pb, show a slight undercooling. Nevertheless they can be used for heat calibration, and possibly also for temperature
calibration during cooling.