Sensitive spectrofluorimetric method for the determination of ethylenediaminetetraacetic acid and its salts in foods with zirconium ions and Alizarin Red S in a micellar medium

A simple and very sensitive method for the spectrofluorimetric determination of ethylenediaminetetraacetic acid (EDTA) in foods is proposed. The method involves the reaction of EDTA with Zr(IV) and Alizarin Red S to produce a ternary complex which exhibits a high fluorescence intensity at 600 nm with excitation at 478 nm. In the presence of a cationic micellar medium (hexadecyltrimethylammonium bromide) this emission is greatly enhanced, allowing the establishment of the first spectrofluorimetric determination of EDTA at pH 4.7, with a detection limit of 3.4 ng ml−1. The influence of several substances usually present in commercial foods is discussed. The method has been applied to the determination of EDTA in various foods (mayonnaise, legumes) and the results obtained have been validated by standard addition methodology.