Instant melting point

The determination of the instant melting point is a physical analysis method for the characterization of solids (e.g. drugs ) in the pharmaceutical laboratory. The method is based on a special determination method of determining the temperatures and . It is calculated using the formula: ${\ displaystyle T_ {1}}$ ${\ displaystyle T_ {2}}$

{\ displaystyle {\ text {Instant melting point}} = {\ frac {T_ {1} + T_ {2}} {2}}}

Measuring equipment

The measuring apparatus consists of a metal block (e.g. made of brass ) with good thermal conductivity and a flat, polished surface. The block is heated with an adjustable gas burner or an electric heater. It has a cylindrical bore that is just wide enough to insert a mercury thermometer . The cylindrical bore is positioned parallel to the polished surface at a distance of about 3 mm.

execution

The metal block is quickly brought to a temperature that is about 10 ° C below the expected melting temperature . Heating is then continued at around 1 ° C per minute. At regular time intervals, some particles of the powdered substance to be examined are scattered on the polished surface near the mercury vessel of the thermometer. The surface is cleaned after each sprinkling. If the substance melts for the first time as soon as it touches the metal surface, the temperature has been reached. Then the heating is stopped. When it cools down, particles of the substance to be examined are again scattered onto the block at regular intervals, with the polished surface being cleaned after each scattering. As soon as the substance immediately stops melting, the temperature is read off. ${\ displaystyle T_ {1}}$ ${\ displaystyle T_ {2}}$

Individual evidence

↑ ^a ^b European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, p. 41, ISBN 978-3-7692-3962-1 .

[EuropäischesArzneibuch-1] European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, p. 41, ISBN 978-3-7692-3962-1 .