Improvement of 31P NMR Spectral Resolution by 8-Hydroxyquinoline Precipitation of Paramagnetic Fe and Mn in Environmental Samples

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• 作者：Shiming Ding ; Di Xu ; Bin Li ; Chengxin Fan ; Chaosheng Zhang
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：April 1, 2010
• 年：2010
• 卷：44
• 期：7
• 页码：2555-2561
• 全文大小：212K
• 年卷期：v.44,no.7(April 1, 2010)
• ISSN：1520-5851

文摘

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 Chelex-100 treatments, by improving spectral resolution to a large extent with no detrimental effects on P forms.