Quote Originally Posted by agnosticnikon View Post
I do know that quite a few labs used nitrogen injected into their chemical tanks as a preservative.
Perhaps you are thinking of gas-burst agitation, which was used for stirring up the tanks when I worked with dip-and-dunk processing machines for C41 and E6. Nitrogen itself won't prevent oidation unless you completely replace the air (which is +/- 80% nitrogen anyway) in an impervious chemical container - in practice, that would be awkward to do reliably and consistently.

The heavier-than-air-gas preservative products work by forming a gaseous "lid" over the liquid chemical.