The polypyrrole-based anion selective electrode was reported to be susceptible to interferences from cations as well as anions. However, if the aggressively interfering Ag(I) is implanted during the electrode fabrication, the ise can be inoculated against cation interferences from Cu(II) or Pb(II) of less aggressive cations. In the extreme case of Ag(I) poisoning in measurement, the electrode can be rejuvenated by a simple electrochemical procedure. However, the selectivities of the modified ise will in general differ from those of the virgin ise.