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 colourless crystals or a white, crystalline powder, odourless or with a slight aromatic odour, changes after procedures A and B into a viscous, colourless and transparent liquid with a slight odour.
Gain of moisture
Before exposure to heat and humidity: |
4.5% |
After procedure A: |
10% |
After procedure B: |
10% |
Chromatographic test
Adsorbent: Silica gel G
Solution applied to the plate: Substance dissolved in methanol.
Solvent system:
n-butanol: ...............................6 volumes
acetic acid: .............................2 volumes
water: .....................................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 either left in a chromatographic chamber containing iodine crystals until spots appear or sprayed with a 0.2% solution of triketohydrindene hydrate in acetone and heated at 100 °C.
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 ephedrine do not show the same chromatographic characteristics of migration and detection. The main spot of the reference solution migrates less far than the ones of the solutions of the samples subjected to the test, and for these, an additional spot remains at the point of application.
Ultraviolet spectrophotometry
The absorbance is measured using a 0.05% solution of the samples in 0.1 N sulfuric acid.
| |
263 nm |
257 nm |
251 nm |
Before exposure to heat and humidity |
0.433 |
0.570 |
0.478 |
After procedure A |
0.158 |
0.646 |
0.572 |
After procedure B |
0.562 |
0.961 |
0.884 |
Colorimetric determination
The colorimetric method is based on the formation of picrates extracted into chloroform.
Decomposition is observed.
Conclusion
Ephedrine is subject to decomposition under accelerated degradation conditions.
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