Journal of Soils and Sediments

, Volume 12, Issue 6, pp 909–920

Characterization and optimization of the preparation procedure for solution P-31 NMR analysis of organic phosphorus in sediments

  • Di Xu
  • Shiming Ding
  • Bin Li
  • Fei Jia
  • Xiang He
  • Chaosheng Zhang
SEDIMENTS, SEC 1 · SEDIMENT QUALITY AND IMPACT ASSESSMENT · RESEARCH ARTICLE

DOI: 10.1007/s11368-012-0510-4

Cite this article as:
Xu, D., Ding, S., Li, B. et al. J Soils Sediments (2012) 12: 909. doi:10.1007/s11368-012-0510-4

Abstract

Purpose

The single-step sodium hydroxide–ethylenediaminetetraacetic acid (NaOH–EDTA) extraction is currently the most common preparation technique for the measurement of organic phosphorus (P) composition in sediments using solution 31P nuclear magnetic resonance (NMR). In this study, detailed investigations were conducted to evaluate the performance of this technique, with an objective of finding an optimal procedure for the measurement of sediment organic P.

Materials and methods

A single-step extraction with NaOH–EDTA was investigated on two types of sediment, i.e., Fe/Al-rich sediment and calcareous sediment. The influence of different sediment preparation methods, NaOH–EDTA compositions, solid:solution ratios, extraction time, pre-concentration techniques, and NMR sample frozen storage time on P extraction and solution 31P NMR analysis were investigated.

Results and discussion

Both air- and freeze-drying increased organic P extraction for the calcareous sediment. An extraction time of 16 h was sufficient for quantitative recovery of extracted organic P for both Fe/Al-rich and calcareous sediments. The use of a 1:8 solid:solution ratio achieved stronger NMR signals and greater P diversity than the use of a 1:20 ratio. Extraction of the two sediments with 0.25 NaOH–50 mM EDTA favored 31P NMR detection by reducing the relaxation times required and the risk of organic P degradation compared to the use of stronger NaOH–EDTA solutions. Rotary evaporation was a better technique for pre-concentration of the NaOH–EDTA extracts than freeze drying. The concentrated extracts could be preserved by freezing (−20 °C) for at least 2 months.

Conclusions

An optimized procedure was developed based on these investigations, including freeze-drying of fresh sediments, extraction with 0.25 M NaOH–50 mM EDTA for 16 h using a solid:solution ratio of 1:8, pre-concentration of the extract to the level of ∼10 times of its original concentration using rotary evaporation, and storage of the NMR sample at −20 °C until 31P NMR analysis.

Keywords

Composition Extraction Phosphorus-31 nuclear magnetic resonance Phosphorus speciation NMR Sediment 

Supplementary material

11368_2012_510_MOESM1_ESM.doc (920 kb)
ESM 1(DOC 919 kb)

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Di Xu
    • 1
  • Shiming Ding
    • 1
  • Bin Li
    • 2
  • Fei Jia
    • 3
  • Xiang He
    • 1
  • Chaosheng Zhang
    • 4
  1. 1.State Key Laboratory of Lake Science and EnvironmentNanjing Institute of Geography and Limnology, Chinese Academy of SciencesNanjingPeople’s Republic of China
  2. 2.College of Forest Resources and EnvironmentNanjing Forestry UniversityNanjingPeople’s Republic of China
  3. 3.College of Environmental Science and EngineeringHohai UniversityNanjingChina
  4. 4.GIS Centre, Ryan Institute and School of Geography and ArchaeologyNational University of IrelandGalwayIreland

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