title: Assessment of preparation methods for organic phosphorus analysis in phosphorus-polluted Fe/Al-rich Haihe river sediments using solution 31P-NMR.
abstract: Fe/Al-rich river sediments that were highly polluted with phosphorus (P) were used in tests to determine the optimum preparation techniques for measuring organic P (Po) using solution (31)P nuclear magnetic resonance spectroscopy ((31)P-NMR). The optimum pre-treatment, extraction time, sediment to solution ratio and sodium hydroxide-ethylenediaminetetraacetic acid (NaOH-EDTA) extractant solution composition were determined. The total P and Po recovery rates were higher from freeze- and air-dried samples than from fresh samples. An extraction time of 16 h was adequate for extracting Po, and a shorter or longer extraction time led to lower recoveries of total P and Po, or led to the degradation of Po. An ideal P recovery rate and good-quality NMR spectra were obtained at a sediment:solution ratio of 1:10, showing that this ratio is ideal for extracting Po. An extractant solution of 0.25 M NaOH and 50 mM EDTA was found to be more appropriate than either NaOH on its own, or a more concentrated NaOH-EDTA mixture for (31)P-NMR analysis, as this combination minimized interference from paramagnetic ions and was appropriate for the detected range of Po concentrations. The most appropriate preparation method for Po analysis, therefore, was to extract the freeze-dried and ground sediment sample with a 0.25 M NaOH and 50 mM EDTA solution at a sediment:solution ratio of 1:10, for 16 h, by shaking. As lyophilization of the NaOH-EDTA extracts proved to be an optimal pre-concentration method for Po analysis in the river sediment, the extract was lyophilized as soon as possible, and analyzed by (31)P-NMR.
authors.affiliation: State Key Laboratory on Environmental Aquatic Chemistry, Research Center for Eco-Environmental Science, Chinese Academy of Science, Beijing, P.R. China ; University of Chinese Academy of Science, Beijing, P.R. China.
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Zhang
authors.forename: Baoqing
authors.initials: B
authors.lastname: Shan
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Wenzhong
authors.initials: W
authors.lastname: Tang
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D053000:Analytic Sample Preparation Methods / Q000379:methods*; D004492:Edetic Acid / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D010758:Phosphorus / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry; D012996:Solutions; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D009930:Organic Chemicals; D012996:Solutions; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D012972:Sodium Hydroxide; D004492:Edetic Acid; D000535:Aluminum; D007501:Iron