Improvement of31P NMR spectral resolution by 8-hydroxyquinoline precipitation of paramagnetic Fe and Mn in environmental samples

Document Type

Article

Publication Date

4-1-2010

Abstract

Solution 31P nuclear magnetic resonance (NMR) spectroscopy is currently the main method for the characterization of phosphorus (P) forms in environment samples. However, identification and quantification of P compounds may be hampered by poor resolution of spectra caused by paramagnetic Fe and Mn. In this study, a novel technique was developed to improve spectral resolution by removing paramagnetic Fe and Mn from alkaline extracts via 8-hydroxyquinoline (8-HOQ) precipitation. Batch experiments showed that both Fe and Mn were effectively removed by the precipitation at pH 9.0, with the removal efficiencies of 83-91% for Fe and 67-78% for Mn from the extracts of five different environmental samples, while little effect was found on concentration of total P. The 31P NMR analysis of a model P solution showed that addition of 8-HOQ and its precipitation with metal ions did not alter P forms. Further analyses of the five extracts with 31P NMR spectroscopy demonstrated that the 8-HOQ precipitation was an ideal method compared with the present postextraction techniques, such as bicarbonate dithionate (BD), EDTA and Chelex100 treatments, by improving spectral resolution to a large extent with no detrimental effects on P forms. © 2010 American Chemical Society.

Publication Source (Journal or Book title)

Environmental Science and Technology

First Page

2555

Last Page

2561

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