Reversible electrochemical detection of nonelectroactive polyions.

Selective extraction principles for the recognition of nonelectroactive polyions such as heparin and protamine exist, but the high ionic valency renders the extraction process irreversible. A response principle for the reversible detection of such polyions is proposed here. The extraction of the polyionic analyte to the membrane and its subsequent back-extraction is now controlled electrochemically. The principle is established with a protamine electrode, and excellent stability and reproducibility are demonstrated. This method has important implications for the design of chemical recognition principles for polyionic analytes.