Study On ³¹P NMR Analysis Of Organic Phosphorus In Sediment

Nuclear magnetic resonance?NMR?is a used widely analytical tool in modern science.It has been used to the analysis of environmental samples including animal and plant tissues,soils,sediments and so on.³¹P-NMR is the only stable isotope of phosphorus in nature.The mass number of ³¹P-NMR is odd and the spin quantum number of nucleus is half-integer.NMR can be produced of external magnetic field the under condition.Therefore,³¹P-NMR technology can be applied to Po analysis of environmental samples,but the problems of low extraction efficiency of Po and quality of NMR spectra still need to be further improved.In this study,different types of sediments in different lake areas of China were taken as the research objects.The mechanism of the influence of pH,organic matter and paramagnetic ions on the analysis quality of ³¹P-NMR in the liquid phase of Po in sediments was explored by analyzing the pH,organic matter content and paramagnetic ions of different types of sediments,and correlating with the efficiency and quality of the analysis of ³¹P-NMR in the liquid phase of Po in sediments.The ³¹P-NMR analysis method was optimized,and a more general Po liquid-phase ³¹P-NMR analysis method oriented to sediment properties was finally constructed.The results show that:?1?Effect of pH Value on NMR AnalysisTaking sediments with different pH values as research objects,the extraction efficiency of phosphorus from acid-base sediments and the analysis of NMR spectra were studied.The results showed that the extracts with pH 13.7 had higher extraction rates for acidic and alkaline sediments,and five phosphorus compounds could be obtained from the extracts with different pH values,which had no effect on the form of phosphorus,but had effect on the content of different forms of phosphorus in sediments.The extracts with pH 13.7 had higher content of different forms of phosphorus.?2?The effect of paramagnetic ions on NMR analysisTaking sediments with different paramagnetic ion contents as research objects,the phosphorus extraction efficiency and NMR spectra of sediments with different concentrations of EDTA were studied.It showed that the extraction efficiency of Non-calcareous sediments with 25 mmol L^-1 concentration of EDTA was higher than that of calcareous sediments with 50 mmol L^-1 concentration of EDTA.?3?Effect of Organic Matter on NMR AnalysisTaking sediments with different organic matter content as the research object,the phosphorus extraction efficiency and NMR spectra of sediments with different extraction ratios were studied.The results showed that for sediments with organic matter content greater than 100 g.kg^-1 or less than 100 g.kg^-1,the extraction efficiency of sediments with extraction ratios of 1:10 was higher than that of sediments with organic matter content greater than 100 g.kg^-1 or less than 100 g.kg^-1.?4?Character-oriented Po liquid ³¹P-NMR analysis system for sedimentA scientific and efficient liquid phase ³¹P-NMR analysis method should include a series of processes from sample collection to organic phosphorus extraction and on-machine detection map calculation.Although a large number of related researches have been carried out by scholars at home and abroad,the complexity of the physical properties of sediments restricts the standardization of this method.It is necessary to conduct methodological exploration and research before any sediment organic phosphorus analysis.Currently,liquid phase ³¹P-NMR technology is a very effective analytical tool,but only the right use can get meaningful results.In this paper,the method is optimized,and a set of general sediment-oriented Po liquid phase ³¹P-NMR analysis method is constructed.