Eutectic Purity

The substance under investigation should have a defined Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting point and a defined molecular weight.

• This test method is not applicable to materials that decompose during melting.
• You should clean the sample crucible using an appropriate solvent followed by a pre-heating step.
• The measurements should be carried out using
  • a small heating rate, e.g., 0.3 to 0.7 K/min (ASTM E928) or 1 K/min (DIN 51 004/DIN 51 007). A larger heating rate can be applied up to 25 K below the melting effect.
  • a small sample mass (about 1 to 3 mg).
• You should reweigh the sample after completion of the measurement. If the sample lost more than 1 weight %, the data cannot be accepted.

Reduction of the Melting Point due to Impurities in Eutectic Mixtures

• Main component: Phenacetin;
• Impurity: p-aminobenzoic acid.

The increase in the p-aminobenzoic acid amount in the mixture leads to a decreasing Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting temperature and broadening of the melting peak. The mixture melts as a pure substance.