Accelerated Degradation Experiment
Procedure A: 30 days exposure at 50 °C and 100% relative humidity.
Appearance of the substance
The substance, originally in the form of a white to cream-coloured powder, changes after procedure A into a dark brown liquid.
Gain of moisture
Before exposure to heat and humidity:
After procedure A:
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in water.
chloroform: .............................5 volumes
methanol: ................................4 volumes
concentrated ammonia: ...........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 left to dry in air and then examined under ultraviolet light at a wavelength of maximum output at about 254 nm. The plate is then sprayed with 0.25% of triketohydrindene hydrate in acetone and heated at 100 °C until spots appear.
Results: The spot obtained from the solution of the sample subjected to procedure A and the spot obtained from the, reference solution of gentamicin sulfate display the same chromatographic characteristics of migration, but the spot of the sample subjected to the test is less intense. Furthermore, an almost invisible secondary spot appears with the reference solution.
The absorption spectrum is recorded using a 0.05% solution in water.
After procedure A an absorbance at 320 nm is observed, which is not present in the reference solution.
Gentamicin sulfate is subject to decomposition under accelerated degradation conditions.