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 colourless crystals or a white, crystalline powder, shows no significant modification after procedure A, but changes into a yellow liquid after procedure B.
Gain of moisture
Before exposure to heat and humidity: |
none |
After procedure A: |
2% |
After procedure B: |
40% |
Solubility
Dissolve 1 g in 50 ml of water. The solubility does not change after procedure A, but decreases after procedure B.
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in ethane 95% at a temperature of 50 °C.
Solvent system:
n-butanol ............................... 50 volumes
ethane 95% ........................... 25 volumes
concentrated ammonia ........... 10 volumes
water ...................................... 25 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 examined under ultraviolet light at a wavelength of maximum output at about 254 nm.
Results: The spot obtained from the solution of the sample subjected to procedure A and the spot obtained from the reference solution of thiamine mononitrate display the same chromatographic characteristics of migration and detection. After procedure B several secondary spots are revealed.
Ultraviolet spectrophotometry
Before exposure to heat and humidity and after procedure A, the absorbances at 271 nm remain practically the same.
The absorbance decreases to 110 after procedure B.
Potentiometric determination
A non-aqueous titration shows no significant degradation.
Conclusion
Thiamine mononitrate is subject to decomposition only at higher temperatures as seen after procedure B.
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