Today I was reading a document (of International Specialty Products) about allantoin.
I read that allantoin is amphoteric and anionic at basic conditions.
- Does that mean that it is dipolar at a neutral pH?
The supplier suggests to suspend it in emulsions in the cool down phase <50°C. According to them recrystallization can occur later when it has been solubilized >50°C.
I never suspend allantoin, I always dissolve it in the water phase ≥70°C and luckily I've never had recrystallization problems so far.
I read that the solubility in water is 0.45 g/100 g at 25°C, so I guess that if you mix well and let it be, 0.45% of the suspended particles will dissolve later on anyway at room temperature?
A prototype formula was attached: 1% allantoin suspended in an anhydrous, lipophilic body balm.
- Does that actually work, suspending a water soluble, fine powder like allantoin in a lipophilic base?
- Are there other reasons than crystallization alone, to suspend allantoin in the cool down phase?