Qualitative and quantitative 1H NMR spectroscopy for determination of divalent metal cation concentration in model salt solutions,food supplements,and pharmaceutical products by using EDTA as chelating agent |
| |
| Authors: | Elina Hafer Ulrike Holzgrabe Katharina Kraus Kristie Adams James M. Hook Bernd Diehl |
| |
| Affiliation: | 1. Spectral Service AG, Cologne, Germany;2. Institut für Pharmazie und Lebensmittelchemie, Julius-Maximilians-Universität, Würzburg, Germany;3. Steelyard Analytics Inc., Gaithersburg, MD, 20878 USA;4. School of Chemistry and Mark Wainwright Analytical Centre, University of New South Wales, Sydney, New South Wales, Australia |
| |
| Abstract: | This paper introduces an 1H NMR method to identify individual divalent metal cations Be2+, Mg2+, Ca2+, Sr2+, Zn2+, Cd2+, Hg2+, Sn2+, and Pb2+ in aqueous salt solutions through their unique signal shift and coupling after complexation with the salt of ethylenediaminetetraacetic acid (EDTA). Furthermore, quantitative determination applied for the divalent metal cations Ca2+, Mg2+, Hg2+, Sn2+, Pb2+, and Zn2+ (limit of quantification: 5–22 μg/ml) can be achieved using an excess of EDTA with aqueous model salt solutions. An internal standard is not required because a known excess of EDTA is added and the remaining free EDTA can be used to recalculate the quantity of chelated metal cations. The utility of the method is demonstrated for the analysis of divalent cations in some food supplements and in pharmaceutical products. |
| |
| Keywords: | complexation EDTA food supplements metal ions NMR spectroscopy pharmaceutical products |
|
|
