Use of ion binding ligands attached to solid supports and membranes for ion removal from a biological system

A method for making a biological solution containing a known concentration of one or more ion species, comprising:

• (a) contacting a biological solution containing one or more ion species and wherein one or more biological functions may occur with a composition represented by the formula:
• S-B-L
• wherein S is a substrate, L is any ion-binding ligand having an affinity for said one or more ion species and having a functional group for attachment to S, and B is a covalent linkage mechanism which attaches S to L, such that a complex between said one or more ion species and L is formed;
• (b) removing the biological solution from contact with the composition, whereby the concentration of said one or more ions in the solution is reduced;
• (c) repeating steps (a) and (b) until the biological solution is essentially free of said one or more ions;
• (d) adding to the biological solution a known quantity of said one or more ion species;
• thereby making a biological solution containing a known concentration of said one or more ion species.

A method for preferentially removing calcium ion species from a protein-containing biological solution comprising:

• (a) contacting a biological solution containing a protein and a calcium ion species with a composition represented by the formula:
• S-B-L
• wherein S is a substrate, L is any ion-binding ligand having an affinity for said calcium ion species and having a functional group for attachment to S, and B is a covalent linkage mechanism which attaches S to L, such that a complex between said calcium ion species and L is formed;
• and
• (b) removing the biological solution from contact with the composition, whereby the concentration of said calcium ion species in the solution is reduced.