The nitrogen and oxygen donor sites in close proximity or the aminocarboxylic acid groups in aminoacids, tends to form stable complexes with metal ions, and also lanthanide ions are gaining increasing importance due to their close resemblence and the need to extract and separate them from each other.
In present investigation the aminoacid-Rare earth systems have been studied. This study is undertaken by the Calvin-Bjerrum's potentiometric titration technique. and PL is determined. Using these values the metal-ligand and proton-ligand stability constants have been determined and reported. The solvents used were: water and 50%
DMSO, DMF, Methanol and isopropanol.