Accelerated Degradation Experiment

Conditions

Procedure A: 20 hours exposure at 50 °C and 100% relative humidity.

Appearance of the substance

The substance, originally in the form of a white or almost white powder, changes after procedure A into a hard, yellow mass.

Gain of moisture

Chromatographic test

Adsorbent: Silica gel F-254

Solution applied to the plate: Substance dissolved in water.

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 examined under ultraviolet light at a wavelength of maximum output at about 254 nm, and then left in a chromatographic chamber containing some iodine crystals until spots appear.

Results: The secondary spots obtained from the solution of the sample subjected to procedure A are more numerous than the corresponding spots obtained from the reference solution of ampicillin sodium.

Iodometric determination

After procedure A, the degradation was assessed at 73%.

Ultraviolet spectrophotometry

Prepare a 0.1% solution of the sample subjected to procedure A in water. Dilute 2 ml to 100 ml with buffered copper sulfate solution (dissolve 15.22 g of anhydrous disodium hydrogen phosphate in 536 ml of water, add sufficient aqueous 2.1% citric acid solution until a pH of 5.15-5.25 is reached - about 464 ml. Mix 985 ml of this buffer solution to 15 ml of aqueous 0.393% copper(II) sulfate solution). Heat 10 ml to 75 °C for 30 minutes, cool and measure the absorbance at about 320 nm, using the unheated buffered copper sulfate solution as a blank.

Conclusion

Ampicillin sodium is subject to strong decomposition under accelerated degradation conditions.