- The melting point determined by the capillary method is the temperature at which the last solid particle of a compact column of a substance in a tube passes into the liquid phase.
- Unless otherwise prescribed, dry the finely powdered substance in vacuum and over anhydrous silica gel R for 24 h or at a temperature specified in the monograph
- Transfer a quantity of the dried powder by tapping the tube on a hard surface (ensure the capillary tube bottom is not damaged or cracked).
- The capillary tube closed at one end and dimensions suitable for the apparatus used.
- Raise the temperature of the instrument to about 10 °C below the presumed melting point and then adjust the rate of heating to about 1 °C/min.
- When the temperature is 5 °C below the presumed melting point, correctly introduce the capillary tube into the instrument.
- Record the temperature at which the last particle passes into the liquid phase
Determination Of Melting Point for API
Mohamed Khaled
QA Senior Specialist – Master’s Degree in Quality Management – IRCA Certified Lead Auditor