CONDENSATION OF CO++ IONS ON CHONDROITIN SULFATE FROM TRANSPORT-COEFFICIENTS AND PROTON NMR MEASUREMENTS IN AQUEOUS-SOLUTIONS

The “condensed” counterions which characterize high‐charge‐density polyelectrolyte solutions can be analyzed into two subpopulations: (1) site‐bound counterions and (2) atmospherically entrapped counterions. The distinction is achieved experimentally by combining the data from self‐diffusion coefficient or electrical mobility measurements, which give the amount of “condensed” ions, and those from nmr, chemical shift measurements, which indicate the amount of site‐bound ions. In the case of a solution of chondroitin sulfate with excess Co++ counterions, it can be estimated that 20% of the structural charge of the polyion is neutralized by site‐bound, dehydrated, condensed counterions, while a further 30% is neutralized by atmospherically entrapped, hydrated counterions. Copyright © 1979 John Wiley & Sons, Inc.