CHROMATOGRAPHIC DETERMINATION OF METAL-EDTA COMPLEXES WITH POSTCOLUMN DETECTION USING FLUORESCENT TERNARY COMPLEXES

The ubiquitous use of ethylenediaminetetraacetic acid (EDTA) and the difficulties in removing EDTA from waste water results in the release of EDTA, into the environment. Once there, EDTA alters the distribution and transport of heavy metals. In this report, an ion chromatographic method is described for the separation of several metal complexes of EDTA. Subsequent postcolumn formation of a coordination-unsaturated ternary complex between the EDTA, lutetium, and 8-hydroxyquinoline-5-sulfonic acid results in detection limits of 1 x 10(-7) M (2 ng) for EDTA complexes of Pb2+, Zn2+, Cu2+, and Cd2+, with linear response to 1 x 10(-5) M (200 ng). These detection limits are 1 order of magnitude more sensitive than comparable absorbance-based postcolumn reaction detection schemes. In this paper, the use of ternary coordination unsaturated complexes as a postcolumn reagent for metal chelates is introduced and issues regarding the kinetics of the postcolumn reaction are discussed.