6 Operation
21
Melting Point M-560 Operation Manual, Version G
6.2
Melting point determination
NOTE
For exact melting point determination, use original capillaries from BUCHI only. If other capillaries are
used, the results may be inaccurate. Use the following items:
Product
Order number
Melting point capillaries, 100 units
017808
Melting point capillaries, 1000 units
001759
Fig. 6.1: Melting point capillaries
6.2.1
Sample preparation
NOTE
Use only capillaries from BUCHI. They are precise and adequate for this kind of operation. Other
capillaries have other dimensions and wall thicknesses. Using others may result in results that are
incorrect.
Each sample has to be prepared.
The following methods to compact the samples are recommended:
• Using the Sample Loader M-569
• Knocking the capillaries on a hard surface.
NOTE
Sample preparation by letting the capillaries fall through a tube is not advised, because cross
contamination may occur.
Preparation of the samples:
• The samples being investigated must be fully dry, homogenous and in powdered form. Moist
samples must be dried first (the pharmacopoeias prescribe that the substance needs to be dried
in a vacuum for 24 hours over silica gel R). Coarse crystalline samples and non-homogeneous
samples are finely ground in a mortar.
• To fill the capillary tubes with the sample, the open ends of the tubes are pressed into the
substance. The substance is moved to the bottom of the tubes by repeatedly tapping the tubes
against a hard base.
• Enough substance must be filled into the glass capillary to form a compact column 4–6 mm in
height. (A height of 4–5 mm is recommended for precision measurements.) To ensure compa-
rable results, it is important to fill all three capillary tubes to the same height and to compact the
substance well in the tubes using the Sample Loader M-569.
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