Pharmalytes are part of the IPG-rehydration recipe of most suppliers.
These molecules too big for getting washed out in the 2 eqilibration steps after the first dimension. During the second dimension they produce unsoluble SDS-complexes.
Unfortunable they get stained with Coomassie and silver if not performing the additional washing steps or starting directly with TCA* (silver staining)
*TCA = Trichloroacetic Acid