1987 Volume 34 Issue 9 Pages 603-607
A method is described for the determination of ethylenediaminetetra-acetic acid (EDTA) and its metal chelates in foods. The principle of the method is that free copper ion (Cu2+) reacts with bathocuproine but EDTA-Cu does not under definite condition. Food samples were homogenized with 0.1M NaOH, then subjected to equilibrium dialysis against 0.02M NaOH. EDTA and its metal chelates in the dialyzate were converted into EDTA-Cu at pH 2.5 by the addition of CuSO4. This solution was then divided into two portions of equal volume. One portion was subjected to assay of free Cu2+, and the other to assay of total (the sum of free and chelated) Cu2+. EDTA was calculated from the difference between the absorbances (477nm) obtained with free and total Cu2+. Analyses of several foods with EDTA-Ca added showed the recovery of 88.7-99.4% for 50μg/g and 92.7-99.9% for 250μg/g. Food ingredients such as organic acids, proteins, amino acids, peptides, phenolic compounds and emulsifying agents were without interferences.
