CHROMATOGRAPHIC DETERMINATION OF COMMERCIAL FE(III) CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID, ETHYLENEDIAMINEDI(O-HYDROXYPHENYLACETIC) ACID AND ETHYLENEDIAMINEDI(O-HYDROXY-P-METHYLPHENYLACETIC) ACID

The use of synthetic iron chelates is the most common and effective wa y to treat iron chlorosis in plants. Using an ion-pair HPLC method pre viously proposed by the authors, it was found that the older commercia l products reached the percentage of Fe chelated indicated by the manu facturer, but in no case did the current products reach their nominal, or legal, composition. Moreover, the current products of Fe-ethylened iaminedi(o-hydroxyphenylacetic) acid (FeEDDHA) showed significant addi tional chromatographic peaks that, based on published synthesis pathwa ys for these type of compounds, may correspond to para-para FeEDDHA or ortho-para FeEDDHA, sterically-hindered isomers of FeEDDHA which are of little or no value as an iron chelate for agricultural purposes. (C ) 1997 Elsevier Science B.V.