Rudi;

With a straight reaction which is what takes place, you get 1 equivalent of AA and 1 eq of Phenidone. If it were catalyzed you might see 100 AA to 1 PD and the PD might be regenerated entirely. This is the case of AA + Iron + Oxygen. You get an Iron catalyzed decomposition of AA which is the bane of all AA developers.

Unless you have a secret ingredient that stops this reaction.....

PE