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 colourless crystals or a white, crystalline powder, changes after procedure A into a humid, light greyish yellow mass. After procedure B two phases appear, an upper clear liquid phase, orange-red in colour, and a lower solid phase of clear crystals.
Gain of moisture
After procedures A and B: 50%
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in water.
Solvent system:
chloroform ........................ 90 volumes
methanol ............................ 20 volumes
concentrated ammonia ....... 2 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.
Results: The spot obtained from the solution of the sample subjected to procedure A and the spot obtained from the reference solution of pyridoxine hydrochloride display the same chromatographic characteristics of migration and detection. No secondary spots are revealed. After procedure B, the chromatogram performed on the upper liquid phase shows tailing and a less mobile secondary spot behind the main spot. No secondary spots were obtained from the solid phase.
Conclusion
No decomposition is observed by thin-layer chromatography after procedure A, but after procedure B the substance changes as seen from its appearance, gain of moisture and the thin-layer chromatography.
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