I have multiple , unused packets of the part A bleach from Kodak Sepia Toner kits (I need to replace the toner after a small number of prints, but the bleach keeps working so end up with these left over). It contains potassium ferricyanide and potassium bromide. Anyone know if this could be used to make cyanotype part A (usually just potassium ferricyanide)? Then I'd just have to buy ferric ammonium citrate.

I think the bromide would probably interfere with the process. I may be wrong about that, but potassium ferricyanide is cheap in the general scheme of things, so I would just buy fresh chemistry anyway.