A chelating gel for collection of copper from seawater

An affinity Chromatographic gel is coupled to carboxymethyl(imino)-bis(ethyl-enenitrilo) tetraacetic acid (DTPA) by a carbodiimide reaction. This gel is successful in extracting copper from seawater with high selectivity over alkaline earths such as mag-nesium. It is useful over a wide range of pH (4–9), and is stable and reversible over a period of nine months. Up to 20 μmol of copper can be adsorbed and recovered with greater than 99% efficiency with gel—DTPA prepared from 1 g of dry gel.