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 5 days at 70 °C and 100% relative humidity. |
Appearance of the substance
The substance, originally in the form of a white or almost white, crystalline powder, changes after procedure A into a rose beige, slightly agglomerated and sticky powder, and after procedure B into a darker beige powder containing chestnut-coloured particles.
Gain of moisture
Before exposure to heat and humidity: |
0.6% |
After procedure A: |
3% |
After procedure B: |
1.2% |
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in water.
Solvent system:
chloroform: ..............................70 volumes
methanol: .................................30 volumes
concentrated ammonia: ..............1 volume
Development conditions: The solvent is allowed to migrate until the front reaches a line 15 cm from the starting line.
Detection: After drying the plate at about 35 °C for 2 hours, it is left in a chromatographic chamber containing some iodine crystals until spots appear.
Results: The spots obtained from the solutions of each of the samples subjected to procedures A and B, and the spots obtained from the reference solution of hydralazine hydrochloride display the same chromatographic characteristics of migration and detection. No additional secondary spots are revealed.
Colour of solution in water
After procedures A and B: dark yellow.
Ultraviolet spectrophotometry
After procedures A and B: no change is observed in the spectra.
pH value
Prepare a 1% aqueous solution, allowing to stabilize for 1 hour before measurement.
Before exposure to heat and humidity: |
4.8 |
After procedures A and B: |
4.1 |
Conclusion
No decomposition is detected by thin-layer chromatography and by UV, but the appearance of the substance and the coloration of the solution in water after procedures A and B indicate degradation.
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