Decomposition at the Melting Point, Dihydroergotamine Mesylate - METTLER TOLEDO

Decomposition at the Melting Point, Dihydroergotamine Mesylate

SampleDihydroergotamine mesylate

Dihydroergotamine mesylate

 

Application

Active ingredient

 

Conditions

Measuring cellsDSC820 or TGA850

Pan: Aluminum 40 µl or 100 µl, with pierced lids

Sample preparation: As received, no preparation

DSC measurement: Heating from 30 °C to 300 °C at 20 K/min

TGA measurement: Heating from 30 °C to 300 °C at 20 K/min, blank curve corrected

Atmosphere: Nitrogen, DSC: 50 cm3/min, TGA: 80 cm3/min

 

 

Interpretation

The substance decomposes at its melting point of 219 °C. An indication of this is the exothermic peak in the DSC curve. This interpretation is confirmed by the TGA curve which shows a drastic loss of weight in this region. Before this, at lower temperatures, the sample loses moisture, the calculated content being approximately 3%. Only slight indications of this can be seen in the DSC curve.

The measurement of the heat of fusion should be treated with care since the melting and decomposition processes overlap. The selection of a faster heating rate could possibly shift the decomposition to higher temperature and allow a better evaluation.

 

Evaluation

Onset temperature determination and integration of the melting peak of the DSC curve.

DSC melting peakTGA drying step
Onset, °CΔH, J/gStep, %Evaluation range, °C
219.999.42.935 to 130

 

Conclusion

Frequently, it is not possible to explain thermal effects completely with just one analytical technique. Only when a combination of different methods or variations of measurement conditions are employed is it possible to gain a more complete picture of the processes taking place. Melting points of substances that decompose can only be determined using high heating rates. The required heating rates of 20 – 50 K/min can not be attained with classical melting point equipment.

 

Decomposition at the Melting Point, Dihydroergotamine Mesylate | Thermal Analysis Application No. HB801 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals