Hi askingand knocking,
I use the store bought 3% myself and it works just fine !
When people get to be so concerned about very minor details as maybe it has something not good in it and do not want to use it for these fears, "YET" eat at Mc Donalds etc or drink a coke or pepsi, they are getting "MORE" "POISONS" from eating out than from the 3% peroxide !
And you may be in more danger each time you get out on the highway and travel in a car !
Trying to be a "PUREST" has too many problems !
Smile Tis your choice.