In Situ Sampling And Measurement Of Dissolved Phosphorus And Molybdenum In Water By Diffusive Gradients In Thin Films Technique

The diffusive gradients in thin-films(DGT)technique is a kind of new in situ sampling technique,and it has been applied to the separation and preconcentration of heavy metal and nutration speciation in water,soil and sediment.The bioavailability of phosphorus and molybdenum are strongly affected by its chemical speciation rather than its total mass,and different species will produce different environmental effect and toxicity effect.In recent years,the study of effective speciation of phosphorus and molybdenium has become one of the most major tasks in the research of phosphorus and molybdenum bioavailability.However,the speciation of phosphorus and molybdenum measured by DGT has seldom been reported.In this study,PQAS-DGT device has been build with PQAS as the binding phase and cellulose acetate dialysis membrane as the difftusive phase to collect dissolved phosphorus(DRP)and dissolved molybdenum(DRM)in water.And it is combined with UV-VIS spectrophotometric method to build a new technique which can collect and measure DRP and DRM in the water.The DRP uptake of PQAS-DGT has a linear relationship with deployment time(r2=0.9993)in added spining synthetic solution,and the recovery of standard addition is 98.7%.The DRP uptake of PQAS-DGT has no significant difference in the range of ionic strength(0.0001-0.1mol/L NaNO3)and pH(3-10),so PQAS-DGT can be applied to the in situ collection and measurement of DRP in water.The concentration of DRP in waste water and river are 32.9±0.9?g/L and 4.9±0.4?g/L respectively,using combination of PQAS-DGT sampling technology and ammonium molybdate spectrophotometry.The DRM uptake of PQAS-DGT has a linear relationship with deployment time(rz=0.9989)in added spining synthetic solution,and the recovery of standard addition is 98.8%.The DRP uptake of PQAS-DGT has no significant difference in the range of ionic strength(0.0001-0.1mol/L NaNO3)and pH(4-10),so PQAS-DGT can be applied to the in situ collection and measurement of DRM in water.The concentration of DRM in river is 3.21?g/L,using combination of PQAS-DGT sampling technology and potassium thiocyanate spectrophotometry method,and the recoveries of the spiked Mo(?)were 97.3-101.5%.