title: Electrospray ionization collision-induced dissociation mass spectrometry: a tool to characterize synthetic polyaminocarboxylate ferric chelates used as fertilizers.
abstract: Fertilizers based on synthetic polyaminocarboxylate ferric chelates have been known since the 1950s to be successful in supplying Fe to plants. In commercial Fe(III)-chelate fertilizers, a significant part of the water-soluble Fe-fraction consists of still uncharacterized Fe byproducts, whose agronomical value is unknown. Although collision-induced dissociation (CID) tandem mass spectrometry (MS/MS) is a valuable tool for the identification of such compounds, no fragmentation data have been reported for most Fe(III)-chelate fertilizers. The aim of this study was to characterize the CID-MS(2) fragmentation patterns of the major synthetic Fe(III)-chelates used as Fe-fertilizers, and subsequently use this technique for the characterization of commercial fertilizers. Quadrupole-time-of-flight (QTOF) and spherical ion trap mass analyzers equipped with an electrospray ionization (ESI) source were used. ESI-CID-MS(2) spectra obtained were richer when using the QTOF device. Specific differences were found among Fe(III)-chelate fragmentation patterns, even in the case of positional isomers. The analysis of a commercial Fe(III)-chelate fertilizer by high-performance liquid chromatography (HPLC) coupled to ESI-MS(QTOF) revealed two previously unknown, Fe-containing compounds, that were successfully identified by a comprehensive comparison of the ESI-CID-MS(2)(QTOF) spectra with those of pure chelates. This shows that HPLC/ESI-CID-MS(2)(QTOF), along with the Fe(III)-chelate fragmentation patterns, could be a highly valuable tool to directly characterize the water-soluble Fe fraction in Fe(III)-chelate fertilizers. This could be of great importance in issues related to crop Fe-fertilization, both from an agricultural and an environmental point of view.
authors.affiliation: Department of Plant Nutrition, Aula Dei Experimental Station, CSIC, P.O. Box 13034, E-50080 Zaragoza, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Orera
authors.forename: Jesús
authors.initials: J
authors.lastname: Orduna
authors.forename: Javier
authors.initials: J
authors.lastname: Abadía
authors.forename: Ana
authors.initials: A
authors.lastname: Alvarez-Fernández
mesh_terms: D000465:Algorithms; D002614:Chelating Agents / Q000032:analysis* / Q000737:chemistry; D005308:Fertilizers / Q000032:analysis*; D058085:Iron Compounds / Q000032:analysis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D002614:Chelating Agents; D005308:Fertilizers; D058085:Iron Compounds