NEW METHOD TO DETERMINE STABILITY-CONSTANTS OF LANTHANIDE-EDTA COMPLEXES BY ISOTACHOPHORESIS

The zone reduction in the isotachophoretic migration of several lantha nide-EDTA complexes at low pH was investigated. The typical leading el ectrolyte was 20 mM HCl buffered by triglycine at pH 3.1 and the termi nating electrolyte was 20 mM ammonia solution buffered by acetic acid at pH 4.8. It was observed that a good linear relationship exists betw een the stability constants and the zone reduction due to the bleeding effect (liberating free metal ions). This relationship is the basis o f a new method for the evaluation of the stability constants of the la nthanide complexes. (C) 1997 Elsevier Science B.V.