[KBriggs]

Hey all,

I need to make high pH (12-14) solutions which are stable in small quantities in air over a period of at least 24 hours (drift less than 0.2 in either direction is ideal).

My current ones all drop to around pH 10 overnight regardless of the pH I set at the start.

I am using 1M KCl salt solution and adjusting the pH with KOH.

Any suggestions for buffers or techniques I can use to stabilize them?

[AWK]

You should use a neutral gas atmosphere or remove CO₂ from air.

[KBriggs]

Unfortunately this is not an option for the current setup. Are there any others?

[Arkcon]

Barium hydroxide solutions react with atmospheric CO2 just like other hydroxide solutions, but barium carbonate is insoluble, and can be rapidly filtered out.  Would that help you application?

[KBriggs]

Unfortunately no - any precipitate in the solution at any point in the experiment would ruin it entirely.