[Free9s]

Hello chemists.
I hope someone can answer my question please.

Should I measure the pH value after each addition of active ingredients in my cosmetic formula to ensure that the active ingredient remains within its stability range?"
For example, I have an Alpha Arbutin serum that is stable at a pH of 5-7. I added aloe vera juice to the water, and when I measured the pH, I found it to be 3.8.Should I raise the pH to 5 for the Alpha Arbutin, or is it unnecessary?
Thanks in advance.

[Borek]

Note: per forum rules in general we don't help in making your own medicines or cosmetics. However, this question is more about chemistry itself than about exact particular recipe, so for now I will let is stand.

Definitely if the pH goes down compounds that are pH sensitive will start decomposing. But it is not an instant process, so _if_ further steps in preparation can get the pH in the right range I would try to avoid adding additional components, at the same time doing the prep as fast as possible, to keep pH low for as short as possible. Or I would look into alternative orders of mixing.

But if that's already the final composition yes, adding something to raise pH is a must.

[Free9s]

What do you mean?

But I don't want to make the ph low, it's already low I want make it at ph 5

[Borek]

What do you mean?

No idea which part of what I wrote is unclear for you.

[Free9s]

Here: _if_ further steps in preparation can get the pH in the right range I would try to avoid adding additional components

I think you meant can't get the ph... but not can because that doesn’t make sense

[Borek]

Imagine you have to mix three things - something A that is sensitive to pH with B that lowers pH and C that raises pH. You mix A+B and the pH is wrong. At this moment you can either add some base to raise the pH to put it in the safe range, or you can quickly mix with C to get the pH back in the safe range*.

Adding C is a further step, and it _can_ put the pH in the right range.

Or is my English failing me completely?

*technically it is more or less the same, adding a base to raise the pH, but the first approach introduces additional compound which can interfere