[nomena]

According to a lab assistant of mine, Fe, Mn and Al cations cannot be seperated during qualitative analysis without using a confirmation test for each seperate anion. He said this has something to do with the creation of coordination complexes, but didn't go into detail. Can anyone shed some light on this for me?

[Arkcon]

The overall idea is very plausible, but we can't know for sure unless we know you exact procedure.  Surely, coordination complexs of one cation with the reagent used to identify another one can muddy the results.  But there's often a work around, if the laboratory allows for it.  Tell us your reagents.