The aqueous phase complexation behaviour of trivalent americium in the
presence of 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane (kryptofix 2
2) was investigated by employing a solvent extraction tracer technique
at a ligand-to-metal ratio as high as 10(5). The extraction behaviour
was studied by using a liquid ion exchanger (dinonylnaphthalene sulph
onic acid) both in high and low pH regions. Though no observable compl
exation is detected at low pH (e.g. pH 2.0), measurable complex format
ion was detected at higher pH values (log beta(L) = 6.05 +/- 0.30).