Patent ID: 7175767

Claim:
A method of preparing a separation medium including a plurality of polydentate metal chelating affinity ligands immobilized to a base matrix, comprising the steps of: (i) providing a compound, having a terminal carboxyl group, of formula (I): R—O—CO—(CH 2 ) n —CHNH 2 —CO—OH (I), wherein R is a selectively cleavable group; and N is an integer from 1–4; (ii) reacting said compound with ethyl alcohol to provide esterification of the terminal carboxylic acid; (iii) derivatizing the reacted compound of step (ii) by adding at least one agent including an electrophile attached to an ethyl-protected carboxylic acid functionality; (iv) selectively cleaving R from the reacted compound of step (iii) to provide one free carboxylic acid functionality; and (v) immobilizing the compound that results from the step (iv) to a base matrix via said free carboxylic acid functionality, followed by deprotecting the remaining carboxylic acid groups by hydrolysis.