| Purity Determination is a program for determining the purity of a material through analysis of the DSC melting peak. |
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The following features set this program apart from the known solutions as well as from ASTM E 928:
- 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%
- 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
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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.
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| 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/°C |
melting temperature of the pure substance,
extrapolated temperature for 1/Partial Area => 0. |
| TempClear/°C |
temperature is obtained through extrapolation of 1/Partial Area ->1. |
| TempBegin/°C |
temperature for which the Partial Area = 0.1, |
| 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. |
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| Error in purity determination caused by approximation routines. |
| These errors are avoided in NETZSCH Purity Determination by using a non-linear regression routine. |
Purity Determination
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