Colorimetric determination of ethylenediaminetetra-acetic acid in foods.

A simple colorimetric method is described for the determination of ethylenediaminetetra-acetic acid (EDTA) in three kinds of foods. The samples were homogenized with 0.1 N-NaOH, then subjected to equilibrium dialysis against 0.02 N-NaOH. EDTA in the dialyzate was converted into a Cu-EDTA complex by the addition of CuSO4. Afterwards, this solution was subjected to the determination of both free and total (free plus complexed) copper ion. EDTA was calculated from the difference between the absorbances (477 nm) obtained with free and total copper ions. Analyses of mayonnaise, dressings and canned mushroom samples with EDTA added at the 1-mM level showed a recovery of greater than 98%.