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:
- 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
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.
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). |
The results can be printed out with the graph.