Test No. 113: Screening Test for Thermal Stability and Stability in Air

This Test Guideline describes methods for determining storage stability of a substance with respect to heat and air. Two methods are applicable to homogeneous solid and liquid substances and to mixtures of these: the accelerated storage test and the thermal analysis methods.

In the accelerated storage test (CIPAC), a long duration storage instability can be simulated by applying a higher temperature during a short test. This test calls for the controlled storage at 54°C to 55°C for 14 days and subsequent analysis. In simple cases, it will be enough to determine a characteristic property before and after storage. The substance is considered to be stable at room temperature if the melting point has remained constant or the content of original substance as determined by analysis has decreased by not more than 5 per cent.

In the thermal analysis methods (TGA and DTA), the sample and the standard reference material are heated up to the final temperature at a constant rate in a defined test atmosphere, either separately in a TGA or DTA apparatus, or in a combined system. The weight change of the sample or the quantities of heat absorbed or given off are measured and recorded. The substance is considered to be stable at room temperature if no decomposition or chemical transformation is found below 150°.

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