Effect of proteins on the response of anion‐selective electrodes based on vitamin B₁₂ derivatives

The potentiometric response of several polymer membrane based ion‐selective electrodes prepared with hydrophobic vitamin B₁₂ derivatives is described. The effect of different proteins on the properties of these electrodes is discussed. It is suggested that the observed changes in potential upon addition of proteins are due mainly to nonspecific interactions between the proteins and the polymer membrane. Reduction of the nonspecific binding effect is possible by using a polymer matrix that contains free hydroxyl groups. The observed results agree with a theoretical model, which predicts that the nonspecific binding effect is more evident when membranes loaded with relatively small amounts of ionophore are used. The implications of these observations for the development of biosensors are discussed.