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 4 days at 70 °C and 100% relative humidity. |
Appearance of the substance
The substance, originally in the form of a colourless to pale yellow, mostly amorphous powder remains unchanged after procedure A, but is transformed into a colourless and viscous liquid after procedure B.
Gain of moisture
After procedure A: |
40% |
After procedure B: |
45% |
Chromatographic tests
No migration of the spots could be obtained on silica gel, cellulose, kieselguhr or mixtures of them using 12 different solvent mixtures and 6 different detection methods.
Potentiometric titration
A suspension of the substance containing 0.5 g in 40 ml of water, and titrated with 0.1 N sodium hydroxide shows no change after procedures A and B.
Colorimetric determination
The reaction with the substance is based on the formation of a complex between antimony and iodine ion, absorbance measured at 425 nm. No change is observed after procedures A and B.
Solubility in an aqueous solution
Quantities of 0.05 g of the substance were added to 150 ml of cold water.
Before exposure to heat and humidity: |
insoluble |
After procedure A: |
insoluble |
After procedure B: |
soluble |
Conclusion
Sodium stibogluconate is subject to decomposition under accelerated degradation conditions.
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