The water solubility and aqueous solution stability of Digitonin (Water Soluble) were compared to that of a competitor’s equivalent product. Digitonin solutions (10 w/v%) were prepared at room temperature or at 60℃, and stored at 4℃ for 15 days, prior to optical density (600nm) measurements.

• Compared products:
    - Wako Digitonin (Water soluble)
    - Company A’s water-soluble Digitonin
• Wako Digitonin lot no.: PTF7501
• Tested solubility: 10 w/v%
• Aqueous solution preparation procedure:
    1. Room temperature, mixing for 5 minutes.
    2. Incubation at 60℃ for 5 minutes.
• Aqueous solution storage temperature: 4℃.

Condition 1： Dissolved at Room temperature → Stored at 4℃ for 15 days

• Wako Digitonin (Water Soluble):
  • No notable increase of OD value up to Day 10.
• Company A’s Water Soluble Digitonin:
  • Increase of OD value from Day 1.

Condition 2： Incubated at 60℃ for 5 minutes → Stored at 4℃ for 15days

• Wako Digitonin (Water Soluble):
  • No precipitation observed by the end of the experiment (Day 15).
• Company A’s Water Soluble Digitonin:
  • Precipitation observed on Day 13.

Solubility and stability tests were performed on a 10 w/v% aqueous solution made from a typical lot of Digitonin. Note that 10 w/v% is much higher than the concentration adopted as quality criterion. Wako guarantees 4 w/v% solubility for every lot of Digitonin.