Fluorometric determination of EDTA and EGTA using terbium-salicylate complex.

A method for determining EDTA (ethylenediaminetetraacetic acid) based on a highly fluorescent terbium-EDTA-salicylic acid complex formation was developed. EDTA from as low as a few picomoles to as high as several nanomoles can be determined in a microtiter plate in 10-20 min. Ethyleneglycol-bis(2-aminoethoxy)-tetraacetic acid (EGTA) also can be determined by the same method, but its sensitivity is ca. 14-fold lower. Interestingly, diethylenetriamine tetraacetic acid did not form fluorescent complex with terbium under the same conditions.