title: Comparison of two analytical methods for the evaluation of the complexed metal in fertilizers and the complexing capacity of complexing agents.
abstract: The aim of this research is to develop an analytical methodology for the determination of complexed element in fertilizers and, then, to obtain an adequate criteria for the inclusion of these products in European Regulations on Fertilizers. This paper compares the CEN method EN 13366:2001, based on the retention of the cations into a sulfonated resin, and an AOAC modified method, based on the precipitation of the inorganic forms at pH 9. A limited interlaboratory trial was carried out to demonstrate the applicability of the AOAC modified method and to study the effect of the removal of organic compounds and the addition of a matrix modifier solution before the element quantification. Then, a global interlaboratory trial was developed to evaluate the validation and quality parameters of the method. As a second objective, the AOAC modified method was applied to the determination of the complexing capacity of complexing agents based on lignosulfonates and amino acids. The AOAC modified method was the choice methodology because it is adequate for the determination of complexing capacity of micronutrients in fertilizer.
authors.affiliation: Departamento de Química Agrícola, Facultad de Ciencias, CVII, Universidad Autónoma, 28049 Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Villén
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Lucena
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Cartagena
authors.forename: Raquel
authors.initials: R
authors.lastname: Bravo
authors.forename: Josemaría
authors.initials: J
authors.lastname: García-Mina
authors.forename: M Ignacia Martín
authors.initials: MI
authors.lastname: de la Hinojosa
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D002412:Cations; D011232:Chemical Precipitation; D005308:Fertilizers / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008031:Lignin / Q000031:analogs & derivatives / Q000737:chemistry; D008670:Metals / Q000032:analysis* / Q000737:chemistry; D012117:Resins, Synthetic; D012995:Solubility
chemical_list: D000596:Amino Acids; D002412:Cations; D005308:Fertilizers; D008670:Metals; D012117:Resins, Synthetic; C001545:lignosulfuric acid; D008031:Lignin