Chemistry Department, Umeå University, Umeå, Sweden.
Environ Sci Technol. 2012 Apr 3;46(7):3950-6. doi: 10.1021/es204016h. Epub 2012 Mar 19.
Organic phosphorus (P) compounds represent a major component of soil P in many soils and are key sources of P for microbes and plants. Solution NMR (nuclear magnetic resonance spectroscopy) is a powerful technique for characterizing organic P species. However, (31)P NMR spectra are often complicated by overlapping peaks, which hampers identification and quantification of the numerous P species present in soils. Overlap is often exacerbated by the presence of paramagnetic metal ions, even if they are in complexes with EDTA following NaOH/EDTA extraction. By removing paramagnetic impurities using a new precipitation protocol, we achieved a dramatic improvement in spectral resolution. Furthermore, the obtained reduction in line widths enabled the use of multidimensional NMR methods to resolve overlapping (31)P signals. Using the new protocol on samples from two boreal humus soils with different Fe contents, 2D (1)H-(31)P correlation spectra allowed unambiguous identification of a large number of P species based on their (31)P and (1)H chemical shifts and their characteristic coupling patterns, which would not have been possible using previous protocols. This approach can be used to identify organic P species in samples from both terrestrial and aquatic environments increasing our understanding of organic P biogeochemistry.
有机磷（P）化合物是许多土壤中 P 的主要组成部分，也是微生物和植物 P 的关键来源。溶液 NMR（核磁共振波谱学）是一种用于表征有机 P 物种的强大技术。然而，（31）P NMR 光谱通常因重叠峰而变得复杂，这阻碍了对土壤中存在的众多 P 物种的鉴定和定量。即使在 NaOH/EDTA 提取后与 EDTA 形成配合物，顺磁金属离子的存在也会加剧重叠。通过使用新的沉淀方案去除顺磁杂质，我们实现了光谱分辨率的显著提高。此外，获得的线宽减小使得可以使用多维 NMR 方法来解析重叠的（31）P 信号。在两个具有不同铁含量的北方泥炭土壤的样品上使用新方案，二维（1）H-（31）P 相关光谱允许根据（31）P 和（1）H 化学位移及其特征偶合模式，对大量 P 物种进行明确识别，这在使用以前的方案时是不可能的。该方法可用于鉴定来自陆地和水生环境的样品中的有机 P 物种，从而增加我们对有机 P 生物地球化学的理解。
