Accelerated Degradation Experiment
Conditions
Procedure A1: |
10 days exposure at 50 °C and 100% relative humidity. |
Procedure A2: |
20 days exposure at 50 °C and 100% relative humidity. |
Procedure A3: |
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 a white or yellowish white powder, changes after procedure A1 into a yellowish pasty mass, after procedure A2 into a yellow liquid paste and after procedure A3 into a liquid.
Gain of moisture
Before exposure to heat and humidity: |
3.5% |
After procedure A1: |
34.5% |
After procedure A2: |
40% |
After procedure A3: |
60% |
Solubility
Solution in water.
Before exposure to heat and humidity: |
clear. |
Samples subjected to the test: |
turbid |
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in water.
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, and then dried and sprayed with a 1% solution of p-dimethylaminobenzaldehyde in ethane 95% containing 1% of concentrated hydrochloric acid.
Results: The spots obtained from the solutions of each of the samples subjected to procedures A1, A2, A3 and B, and the spot obtained from the reference solution of sulfadiazine sodium display the same chromatographic characteristics of migration and detection.
Ultraviolet spectrophotometry
No change is observed in the spectra of the substance subjected to procedures A1, A2, A3 and B dissolved in ethanolic 0.1 N hydrochloric acid.
Diazo-reaction
No change is observed in the absorbances.
Conclusion
Sulfadiazine sodium is subject to decomposition due to the gain of moisture and the formation of sulfadiazine. The reaction is formed through the absorption of carbon dioxide in air, whereas the structure of sulfadiazine itself remains unchanged.
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