[HailoMan]

I have been using a 5M NaOH / Ethanol (50:50 v/v%) to clean up my glasswares and over the few weeks that I've been using the solution, I've noticed that the solution has become more and more orange in colour (originally transparent in colour).
I store the solution in a plastic container (PP container I think)
Does anyone know what cause the orange coloration of the solution?
Prior to cleaning with the ethanolic hydroxide solution, I've cleaned the glasswares with ethanol, followed by 4x tap water rinse, so I'd think that they should be relatively free of traces of organic solvents that I use in my experiments.

For cleaning glasswares, would you recommend that I prepare a fresh solution?

Thank you in advanced

[Arctic-Nation]

Watery sodium ethoxide is rather easily oxidized by oxygen in the air, but as long as you rinse your glassware again afterwards, it shouldn't be a problem. Never heard of this specific cleaning procedure, though. Are you not allowed to you use acetone?

[HailoMan]

Thank you for the explanation.
I wanted to use a base bath with KOH & iPrOH, but since my lab just ran out of both of the chemicals and I didn't want to wait around, I thought that NaOH & Ethanol might be a good alternative.
I need the glass surface relatively clean of organics and I wasn't sure if acetone alone would do the job.

[Honclbrif]

It could be organic residue oxidizing in the basic ethanol.