Accelerated Degradation Experiment
Conditions
Procedure A: |
30 days exposure at 50 °C and 100% relative humidity. |
Procedure B: |
30 days exposure at 50 °C and 100% relative humidity followed by 4 days at 70 °C and 100% relative humidity. |
Appearance of the substance
The substance, originally in the form of a white or creamy white, crystalline powder, changes after procedures A and B into a light cream-coloured powder.
Gain of moisture
After procedures A and B: 2.5%
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in methanol.
Solvent system:
chloroform: .....................7 volumes
acetone: ...........................3 volumes
Development conditions: The solvent is allowed to migrate until the front reaches a line 15 cm from the starting line.
Detection: The plate is left in a chromatographic chamber containing some iodine crystals until spots appear, or the plate is sprayed with the following reagent until yellow spots appear: 1 g of p-dimethylaminobenzaldehyde, 30 ml of ethanol 95%, 30 ml of concentrated hydrochloric acid and 180 ml of n-butanol.
Results: The spots obtained from the solutions of each of the samples subjected to procedures A and B and the spot obtained from the reference solution of dapsone display the same chromatographic characteristics of migration and detection. No secondary spots are revealed.
Conclusion
No decomposition is detected by thin-layer chromatography, but the appearance of the substance changes slightly after procedures A and B.
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