I am trying to find a method to purify/separate phosphorylated protein from unpshosphorylated proteins. I have two approach in my mindGadolinuim-charged IDA with a shallow gradient of imidazole is supposed to separate phosphorylated proteins best. I haven't tried it myself but this would be the first thing I'd try.* ion-exchange * Fe columns, I tried this too but limited success.
If only small quantities are required and native gel separates the species, that's another way of doing it.
Dima