Optimization of Dissolved Nonreactive Phosphorus Concentration in Water of Lake Taihu for 31P-NMR Analysis

KeyWord:concentration of phosphorus  water  Lake Taihu  31P nuclear magnetic resonance (31P-NMR)

Abstract:

      Phosphorus concentration with aluminum(Al) compound is a pretreatment method for the dissolved phosphorus analysis by 31P-NMR.In order to apply this method to concentrating phosphorus in freshwater of Lake Taihu£¬experiment conditions of this method were analyzed£¬including pH of water during Al precipitating dissolved phosphorus£¬amount of Al compound£¬volume of water and type of extractant.The results showed that the amount of Al compound needed in the phosphorus enrichment is related to not only the phosphorus concentration in freshwater£¬but also the volume of water.The best experiment conditions and procedures to concentrate phosphorus for 31P-NMR analysis were selecting 20 L filtration water from Lake Taihu£¬and adding 3 g AlCl3?6H2O in the water (keeping pH value of 6.0).After overnight£¬Al floc containing phosphorus was collected and then redissolved in 0.5 mol?L-1 NaOH+0.1 mol?L-1 EDTA.