Accelerated Degradation Experiment
Conditions
Procedure A1: |
10 days exposure at 50 °C and 100% relative humidity. |
Procedure A2: |
30 days exposure at 50 °C and 100% relative humidity. |
Procedure B: |
30 days exposure at 50 °C and 100% relative humidity followed by 3 days at 70 °C and 100% relative humidity. |
Appearance of the substance
The substance, originally in the form of a light yellow powder, changes after procedure A2 into a yellow to buff-coloured powder and after procedure B into a curdy, yellow to buff-coloured powder.
Gain of moisture
After procedure A2: |
6% |
After procedure B: |
9% |
Chromatographic test
Adsorbent: Neutral aluminium oxide
Solution applied to the plate: Substance dissolved in a mixture of methanol and water (8:2).
Solvent system:
2-propanol: .................................4 volumes
acetone: ......................................2 volumes
concentrated ammonia: ..............2 volumes
Development condition: 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 A1 and A2, and the spots obtained from the reference solution of guanethidine sulfate display the same chromatographic characteristics of migration and detection. After procedure B, two additional spots are revealed, one on the starting line, the other at Rf0.3.
Quantitative determination by colorimetry
Using sodium ferricyanide potassium ferricyanide, the estimated degradation is about 13%.
Conclusion
Guanethidine sulfate is subject to decomposition under accelerated degradation conditions.
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