Color change in closed transparent plastic vials as to closed non transparent serum bottle
I was wondering what were your thoughts.
I formulated a serum and put it in the closed non transparent serum bottle the one it is supposed to go in the market in on stability it passed which no color change and no separation at all.
The same formulation I wanted to see outside at room temperature. One of them I put in the same bottle as on stability and the other in a closed transparent plastic vial .
After about two months outside at room temperature I checked the formulation and the one in the closed non transparent serum bottle the one it is supposed to go in the market in it was still good. But on the other hand the one in closed transparent plastic vial had turned dark pink and it had like layer of pink all over at the top. I have attached a picture for you to see.
It serum in the pipette is the one from inside the closed non transparent serum bottle the one it is supposed to go in the market in after the 2 months.
I felt it is light or maybe oxidation. What do you think could it be.
Thank you so much for your help.