DETERMINATION OF AMINOPOLYCARBOXYLATE LIGANDS USING 8-HYDROXYQUINOLINE-5-SULFONIC ACID-BASED TERNARY COMPLEXES IN CAPILLARY ZONE ELECTROPHORESIS WITH LASER-INDUCED FLUORESCENCE

Aminopolycarboxylate ligands are determined using capillary electropho resis-laser-induced fluorescence. The aminopolycarboxylates are comple xed with lutetium or thorium prior to separation with an electrophoret ic buffer containing 8-hydroxyquinoline-5-sulfonic acid (HQS). The flu orescence signal from the 1:1:1 metal-aminopolycarboxylate-HQS ternary complex is monitored, Lutetium ternary complexes provide a sensitive response for hexadentate aminopolycarboxylate ligands such as ethylene diaminetetraacetic acid, cyclohexanediaminetetraacetic acid, and N-(hy droxyethyl)ethylenediaminetetraacetic acid. The detection limit for ea ch is 2 x 10(-8) M (similar to 7 ng/mL). Thorium ternary complexes pro vide a sensitive response for the octadentate diethylenetriaminepentaa cetic acid I (detection limit of 1 x 10(-7) M) but less sensitive dete ction of hexadentate ligands.