I have found the ampoules under the Magic & Alchemical Items tab but I can't find it under the Alchemist Formulas tab and I have selected "Hide nothing" and "Hide if GM approval needed" is deselected.

I don't think there is an Alchemical Formulas tab. If you're talking about the Alchemical Formulas table under the Alchemist tab, I think that is for adding formulas you get for free as part of your class—which must be common. You'll never find it there because it's an uncommon formula.

You need to go to the Crafting Formulas tab under the Equipment group for additional formulas you want to purchase.

Oh ok thanks for that. Now to work out why it's still showing up blue when I flaged them as GM Aproved.

GM approval doesn't seem to affect PFS characters. It's only applicable to home games, from what I've seen.

Alignment Ampoule generates two warnings when assigned to a PFS character: one for being Uncommon and one for being PFS Limited. The GM Approval list suppresses Rarity-based warnings, but not the PFS specific Limited warnings. You can still suppress the various Limited warnings individually or just ignore them.

I don't know what the developers' intent is for the "PFS Approval" list, but you should probably report "Approval doesn't suppress PFS Limited warnings" as a bug and see what they think.