Quote Originally Posted by srs5694
.. I used Dimezone S rather than phenidone in mine, though, and that could improve the longevity of the solution...
If the solvent was glycol, I would not expect any change in the longevity of the stock solution due to your use of Dimezone S instead of Phenidone.

My stock solution, mixed in Propylene Glycol with Phenidone is still fully active after 3+ years.