Chromatographic determination of Fe chelated by ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid in commercial EDDHA/Fe3+ fertilizers.
EDDHA/Fe3+ chelates are the most common fertilizers used to solve Fe chlorosis in established crops. Commercial products contain two regioisomers, ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,o-EDDHA)/Fe3+ and ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid (o,p-EDDHA)/Fe3+. Although several chromatographic methods exist for the determination of Fe3+ chelated by the o,o-EDDHA isomer, no method has been described for the quantification of Fe3+ chelated by o,p-EDDHA. In this work, factors that affect the behavior of o,p-EDDHA/Fe3+ in ion pair chromatography are reviewed: pH, ion pair reagent, and organic modifier. The best chromatographic performance was obtained with an aqueous mobile phase at pH 6.0 containing 35% acetonitrile and 5 mM tetrabutylammonium hydroxide under isocratic elution conditions. This method was applied to the quantification of commercial samples.
Sección de Química Agrícola, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Sonia
S
García-Marco
Ana
A
Torreblanca
Juan J
JJ
Lucena
D002851:Chromatography, High Pressure Liquid; D005029:Ethylenediamines / Q000032:analysis / Q000737:chemistry*; D005290:Ferric Compounds / Q000032:analysis* / Q000737:chemistry; D005308:Fertilizers / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007502:Iron Chelating Agents / Q000737:chemistry*
D005029:Ethylenediamines; D005290:Ferric Compounds; D005308:Fertilizers; D007502:Iron Chelating Agents; C011813:ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)