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 7 days at 70 °C and 100% relative humidity. |
Appearance of the substance
The substance, originally in the form of a white to yellowish white, crystalline powder, changes after procedures A and B into a light chestnut coloured solution.
Gain of moisture
Before exposure to heat and humidity: |
0.5% |
After procedures A and B: |
34% |
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in methanol.
Solvent system:
methanol ............................ 100 volumes
concentrated ammonia ....... 1.5 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 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 procainamide hydrochloride display the same chromatographic characteristics of migration and detection.
Ultraviolet spectrophotometry
The spectrum recorded between 200 nm and 350 nm of 0.001% solutions of the samples under test in 0.01 N sodium hydroxide, shows an absorption maximum at about 272 nm. No degradation is detected.
Colorimetric determination
The method is based on a diazo-reaction with sodium nitrite, sulfamic acid and naphthylethylenediamine hydrochloride. Absorption maximum: about 550 nm.
After procedures A and B: no degradation is detected.
Conclusion
No decomposition is detected by thin-layer chromatography, ultraviolet spectrophotometry and colorimetric determination, but the appearance of the substance changes after procedures A and B.
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