[Sebastiao]

Hey,

I work in a distillation factory, we work with alcohols, ketones, btex...

from time to time we have some issues with color stability.

The last time, in a product with 4 or 5 different solvents, in just a few minutes the sample goes from completely water clear to dark yellow, almost brown when exposed to sun light.
another sample if kept in dark place, remains water clear for months.

what kind of analysis you suggest i can do to try figured out whats happening in the mixture, and then try to find a solution?

[Arkcon]

There are many options, but off the top of my head, I'd do an HPLC with a PDA detector coupled with an MS, to find the color change component, and identify it by mass spec.

But there may be quicker, industry standard ways, if you know exactly what the mixture is.

Still, if your job is to reclaim solvent, any trace impurity could be there, depending on the specifics just at that time.  So you'll want something definitive to see what the problem is, and remediate or prevent it.