1 Scope
NOTE 1 The substances EDDHA (ethylenediamine-N,N'-di[(hydroxyphenyl)acetic acid] and EDDHMA (ethylenediamine-N,N'-di[(hydroxymethylphenyl)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. HBED (N,N'-bis(2-hydroxybenzyl)-ethylenediamine-N,N'-diacetic acid) does not present isomeric forms.
NOTE 2 At present, analytically pure standards only exist for [ortho,ortho] EDDHA, [ortho,ortho] EDDHMA and HBED. 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.
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![Load image into Gallery viewer, Fertilizers. Determination of chelating agents in fertilizers by chromatography - Determination of Fe chelated by [o,o] EDDHA, [o,o] EDDHMA and HBED, or the amount of chelating agents, by ion pair chromatography](http://checkout-uat.accord.bsi-dev.net/cdn/shop/products/Digital_21eab03f-71ed-40eb-b30a-f359014ebcc1_110x110@2x.png?v=1626447432)