My question is... if an ingredient within a suspended state in whatever it is mixed with to package for relatively long term shelf life is mixed with something else, how long would the active ingredient maintain it potency or effectiveness? An example of what I am referring to is with hair bleaching you must mix two compounds that make the peroxide/bleach portion of this product active thus capable of stripping your hair of color, however, after 30 minutes to an hour it becomes completely inactive. If I were to premix tretinoin, better known as Retin A, with tea tree oil or some other product (aloe, lotion, rosehip seed oil etc), how long would the retinoids remain active? or to they stay active infinitely until the estimated shelf life of the product? How about for salicylic acid? I am aware that with acids such as Glycolic acid and salicylic can be neutralized if you mix these with base alkalines like baking soda rendering them inactive. So does anyone know a rundown or basic list of chemicals or ingredients I should not mix with the following so they maintain their potency:
Glycolic Acid
Salicylic Acid
Tretinoin
Tea Tree Oil
Benzoyl Peroxide
Hydrogen Peroxide
Hi I am not sure if mixing these products will result in something terrible.
For instance you can use tea tree oil or benzoyl first or sacylic acid and after an 30minutes to an hour I would apply trentinoin. You are using more of a systematic approach. The first two ingredient will act as an antibacterial clean out the pore and the trentinoin will act as a shedding agent causing your skin to rapidly shed the new cells or old cells. And i would wait before applying the trentinoin because you need the bp or whatever to dry and absorb first! your skin absobs 80% of what you put on it 
I would also ask your derm about trentinoin microsphere its a different delivery system but it basically traps the medicine in your pores and is working while you sleep too!
good luck