The application of nuclear magnetic resonance (NMR) for the quality control of fertilizers based on Fe3+, Mn2+, and Cu2+ chelates and complexes is precluded by the strong paramagnetism of metals. Recently, a method based on the use of ferrocyanide has been described to remove iron from commercial iron chelates based on the o,o-EDDHA [ethylenediamine-N,N′bis(2-hydroxyphenylacetic)acid] chelating agent for their analysis and quantification by NMR. The present work extended that procedure to other paramagnetic ions, manganese and copper, and other chelating, EDTA (ethylenediaminetetraacetic acid), IDHA [N-(1,2-dicarboxyethyl)-d,l-aspartic acid], and complexing agents, gluconate and heptagluconate. Results showed that the removal of the paramagnetic ions was complete, allowing us to obtain 1H NMR spectra characterized by narrow peaks. The quantification of the ligands by NMR and high-performance liquid chromatography showed that their complete recovery was granted. The NMR analysis enabled detection and quantification of unknown impurities without the need of pure compounds as internal standards.
S. López-Rayo, J. J. Lucena , L. Laghi , M. A. Cremonini (2011). Demetalation of Fe, Mn, and Cu Chelates and Complexes: Application to the NMR Analysis of Micronutrient Fertilizers. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, 59(24), 13110-13116 [10.1021/jf203602a].
Demetalation of Fe, Mn, and Cu Chelates and Complexes: Application to the NMR Analysis of Micronutrient Fertilizers
LAGHI, LUCA;CREMONINI, MAURO ANDREA
2011
Abstract
The application of nuclear magnetic resonance (NMR) for the quality control of fertilizers based on Fe3+, Mn2+, and Cu2+ chelates and complexes is precluded by the strong paramagnetism of metals. Recently, a method based on the use of ferrocyanide has been described to remove iron from commercial iron chelates based on the o,o-EDDHA [ethylenediamine-N,N′bis(2-hydroxyphenylacetic)acid] chelating agent for their analysis and quantification by NMR. The present work extended that procedure to other paramagnetic ions, manganese and copper, and other chelating, EDTA (ethylenediaminetetraacetic acid), IDHA [N-(1,2-dicarboxyethyl)-d,l-aspartic acid], and complexing agents, gluconate and heptagluconate. Results showed that the removal of the paramagnetic ions was complete, allowing us to obtain 1H NMR spectra characterized by narrow peaks. The quantification of the ligands by NMR and high-performance liquid chromatography showed that their complete recovery was granted. The NMR analysis enabled detection and quantification of unknown impurities without the need of pure compounds as internal standards.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
