Quote Originally Posted by albada View Post
I'll need to run some tests to see if Fe(II) and Fe(III) are a problem. It hasn't *appeared* to be an issue with my mix-to-use times of under an hour, but I won't know for certain until I've run tests.
You are unlikely to see much effect since the activity vs. AA content curve is very flat in the region you are looking at. AA decay may explain some of your characteristic curve anomalies you described, though. If you look at Pat Gainer's data plot, 30% less AA is not a big issue as long as you are not concerned with 1/10 of a stop.
Quote Originally Posted by albada View Post
Do you know of an easy way to get a known molarity of these Fe ions in solution? Something better than a rusty nail? In addition, I have some salicylic acid, so I can run with/without tests to see how much difference that makes.
The electrical engineer in me would look at FeCl3 as source of FeIII, but chemists might know better. The trace quantities of FeIII you are going to add make it unlikely that the Cl- has any effect on your developer's properties.
Quote Originally Posted by albada View Post
Your link shows that citric acid is good at sequestering Fe(III) but poor with Fe(II). So what else can be used for Fe(II)? How about histamine?
You could still use DTPA like Xtol, or Dequest as suggested by PhotoEngineer ...
Quote Originally Posted by albada View Post
EDIT: I still haven't seen any data showing that EDTA accelerates the Fenton reaction. I think I'll buy some and try it.
From the second paper I linked to:
EDTA stored in buffer appears not only to lose to some degree its antioxidant potential (arising from chelation of traces of transition metal ions), but in some model systems even to acquire pro-oxidant activity.