ÖNORM EN 13368-3

This European Standard specifies a method for the chromatographic determination of the chelating agent [S,S]-EDDS in fertilizers. The method allows the identification and the determination of the total concentration of the water-soluble fraction of this chelating agent. It does not allow distinguishing between the free form and the metal bound form of the chelating agent. This method is applicable to EC fertilizers containing chelates of one or more of the following micro-nutrients: cobalt, copper, iron, manganese and zinc, covered by Regulation (EC) No 2003/2003 [4]. It is applicable to a mass fraction of the metal chelated of at least 0,35 %. Only the [S,S]-EDDS isomer is allowed by the Regulation (EC) No 2003/2003. Since the Cu chelate of the [R,R]-EDDS isomer presents the same stability as the [S,S]-EDDS, both should coelute. The absence of [R,S]-EDDS indicates that only a pure isomer ([S,S] or [R,R]) exists. An additional test based on polarimetry can be used to ascertain the isomeric characteristic of the sample, or the standard.