Pharmacopeia requirements for melting point determination at a glance include:  Use capillaries with outer diameters ranging from 1.3–1.8 mm and wall thicknesses from 0.1– 0.2 mm. Apply a constant heating rate of 1°C/min. If not otherwise stated, the temperature is recorded point C when no solid substance is left (which corresponds to the clear point). Pharmacopeias such as the United States Pharmacopeia (USP) require the determination of the melting range, where points A (corresponds to collapse point) and C are used for temperature determination. The recorded temperature represents the temperature of the heating stand, which can be an oil bath or a metal block, in which the thermocouple is positioned.
Learn more about how to achieve compliance to local and international pharmacopoeias for melting point determination