This document specifies a method for the chromatographic determination of the iron chelated by each
individual ortho(hydroxy)-ortho(hydroxy) isomer of the chelating agents o,o-EDDHA and o,o-EDDHMA in
fertilizers containing one or both of these substances. The method allows the identification and the
determination of the total concentration of water soluble iron chelates of these chelating agents. It does not
determine the free form of the chelating agents.
NOTE 1 The substances EDDHA (ethylene diamine di(hydroxy phenyl) acetic acid) and EDDHMA (ethylene diamine
di(hydroxy methyl phenyl)acetic acid) exist as several different isomeric forms. Positional isomers for the hydroxyl or
methyl groups (in ortho, meta, and para positions) as well as stereo isomers (meso and dl-racemic forms) are known. Both
meso and dl-racemic forms of the ortho,ortho-EDDHA and ortho,ortho-EDDHMA are positional isomers for the hydroxyl
groups allowed by the Regulation (EC) No 2003/2003. Since para, meta and ortho methyl positional isomers of the
EDDHMA present quite similar stability, they could be grouped: in the method here described the para, meta and ortho
methyl positional isomers of the o,o-EDDHMA are considered together.
NOTE 2 At present, analytically pure standards only exist for ortho,ortho-EDDHA and ortho,ortho-EDDHMA. All other
substances being unavailable as a standard, the influence of their eventual presence in the samples (with respect to the
sensitivity and the selectivity of this method) has not been studied.
NOTE 3 The meso and the dl-racemic forms of o,o-EDDHA and o,o-EDDHMA can be determined separately by this
method.
This procedure concerns EC fertilizers covered by Regulation (EC) No 2003/2003 [5]. It is applicable to a
mass fraction of the metal chelated of at least 0,625 %.
Diese Norm legt ein Verfahren zur chromatographischen Bestimmung des Ions, das mit den einzelnen Ortho(hydroxy)-ortho(hydroxy)-Isomeren der Chelatbildner o,o-EDDHA und o,o-EDDHMA Chelate bildet, in Düngemitteln fest, die eine dieser oder beide Substanzen enthalten. Das Verfahren ermöglicht die Identifizierung und die Bestimmung der Gesamtkonzentration von wasserlöslichen Eisenchelaten dieser Chelatbildner. Das vorliegende Verfahren gilt für EG-Düngemittel, die in der Verordnung (EG) Nr. 2003/2003 behandelt werden. Es gilt für einen Gehalt an chelatisiertem Metall von mindestens 0,625 %.