Question
Posted on: March 6 2013Problem with precipitation of Tretinoin Hydroquina 4% tretinoine 0.03% Vitamin C 0.2% propylene glycol 10% ethanol AQUA DIST AA 100ML
I tried the following:
- the Vit C mixed with propylene glycol and then dissolved in the water (phase 1)
- the Tretinoine and Hydroquina dissolved in the ethanol under heating. Afterwards let Cool (phase 2)
- when merging Phase 1 and 2 a precipitation occurs
Answer
The prescribed method is already mentioned several times between the solved questions.
- Prepare your alcohol phase and apply those in a measuring cylinder and add 10ml propylene glycol;
- dilute with water under constant stirring and under observation of formation of a precipitation.
- forms a precipitate add 10 ml of extra ethanol; mix and see if precipitation dissolves; if not add 10ml ethanol yet.
- dilute further with water as described under 3 to 100ml is reached. Note the total amount of additional ethanol added.
- dissolve on 0.2% vitamin C