Polymeric quaternary NH4+ compds. are used as model substances for a study of the influence of the mol. mass, the chain structure, and charge d. on the equiv. cond. and counter ion activity by both conductometry and direct potentiometry with ion selective electrodes. The latter method yields reliable results down to concns. of only 10-4 monomol/L, whereas conductometry is applicable down to 10-6 monomol/L. [on SciFinder (R)]