Ethylenediaminetetraacetic acid manganese disodium salt hydrate is a metal chelating compound. Cobalt was analysed complexometrically using ethylenediaminetetra-acetic acid (EDTA) by masking aluminum. Previous studies of manganese-EDTA and manganese-EGT-1 complexes indicated that the nitrogen coordination of EDTA resulted in a highly anisotropic spectrum for Mn(II). Lipophilic derivatives of manganese EDTA chelates when incorporated into liposomes confer the greatest hepatic enhancement per micromole of metal ion and have favorable clearance kinetics.