Rapid and simultaneous relaxometric methods to study paramagnetic ion complexes in solution: An alternative to spectrophotometry

Abstract

T1 and T2 relaxation times, measured with rapid and simultaneous continuous wave free precession (CWFP) and Carr–Purcell-continuous wave free precession (CP-CWFP) pulse sequences were used to study complexes of EDTA with paramagnetic ions in solution. The relaxation times of Cu(II)-EDTA and [CuEDTA.NH3]−2 complexes, from pH1 to 13, measured in a 0.47T time-domain nuclear magnetic resonance (TD-NMR) spectrometer show good agreement with the absorbance at approximately 730nm. These methods were also used to study colorless complexes containing paramagnetic ions, not accessible by electronic spectroscopy, such as Mn(II)-EDTA. Therefore, these sequences can be used in any bench top TD-NMR spectrometers as faster alternative to spectrophotometry in analytical routine analyses.