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NETZSCH Purity Determination is a program for determining the purity of a material through analysis of the DSC melting peak.
The following features set this program apart from the known solutions as well as from ASTM E 928:
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determination of purity using the VAN'T HOFF equation
without a mathematical approximation. Thus, the range of application can be extended beyond the threshold of
impurity of 5 mol%. The estimated upper boundary could be 10 mol%
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adjustment of the thermal resistance in such a way that
the nominal value is calculated for a substance with a known degree of purity. This yields not only a high degree of
precision in the high purity range, but substances of a lower purity can be used to determine the thermal resistance |
The names and the molar masses of the substances used are stored in a table and are available after every start.
ASCII-Files serve as the general interface for the transfer of data.
The data can be corrected using three different baselines:
- linear,
- horizontal area-proportional and
- tangential area-proportional.
The non-linear regression automatically links with the baseline determination.
The required initial parameters are prepared in a starting calculation.
Van«t Hoff equation without any approximation
The following are listed in the results:
| Name of Parameter |
Result |
| Impurity/mol% |
concentration of the
impurity(ies) |
| Purity/mol% |
purity, |
| To/ĄC |
melting temperature of the pure substance,
extrapolated temperature
for 1/Partial Area => 0. |
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| TempClear/ĄC |
temperature is obtained through extrapolation of 1/Partial Area ->1. |
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| TempBegin/ĄC |
temperature for which the Partial Area = 0.1, |
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| Correction/% |
correction of the peak area |
| Enthalpy/(kJ/mol) |
melting enthalpy of the substance (measured from the DSC peak).
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The results can be printed out with the graph.
To increase reliability, the results of several measurements can be averaged and the mean printed out with the standard deviation.
Error in purity determination caused by approximation routines.
These errors are avoided in NETZSCH Purity Determination by using a non-linear regression routine.
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