SA-a Liquid Binding Phase For Accumulation And Measurement Of Trace Cd²⁺ And Pb²⁺ In Water By Diffusive Gradient In Thin Film Technique

The diffusive gradients in thin-films(DGT)technique is a kind of new insitu sampling technique,and it has been applied to the separation and preconcentration of heavy metal and nutration speciation in waters,soil and sediment.The binding phase of DGT is devided into solid binding phase and liquid binding phase.Compared with solid binding phase,the liquid binding phase is tightly connected with the diffusive phase,and the elution procedure of the binding phase has been simplified.The liquid binding phase has been developed rapidly in recent years.But the DGT technique that used green liquid binding phase has been rarely reported.Sodium alginate(SA)is an enverimental friendly natural polysaccharide polymer,and it can comlex heavy metal well.In this study,SA-DGT device has been build with SA as the binding phase and cellulose acetate dialysis membrane as the diffusive phase to collect Cd2+and Pb2+in water.And it is combined with atomic asorption spectroscopy(AAS)to build a new technique which can collect and measure Cd2+and Pb2+in water.The Cd2+uptake of SA-DGT has a linear relationship with deployment time(r2=0.9984)in added spining synthetic solution,and the recovery of standard addition is 95.56%.The Cd2+uptake of SA-DGT has no significant difference in the range of ionic strength(0.0001-0.1mol/L NaNO3)and pH(4-6),so SA-DGT can be applied to the insitu collection and measurement of Cd2+in waters.The DGT-liable fraction of Cd2+in lake and river are 15.19%±1.36%and 22.46±2.37%respectively,using combination of SA-DGT sampling technique and AAS.The Pb2+uptake of SA-DGT has a linear relationship with deployment time(r2=0.9997)in added spining synthetic solution,and the recovery of standard addition is 97.54%.The Pb2+uptake of SA-DGT has no significant difference in the range of ionic strength(0.0001-0.01mol/L NaNO3)and pH(4-7),so SA-DGT can be applied to the insitu collection and measurement of Pb2+in waters.The recovery of standard addition of Pb2+in lake and river are 34.70%±5.03%and 42.8±4.22%respectively,using combination of SA-DGT sampling technique and AAS.In addition,the effection of yellow humic acid and EDTA on the measurement of Cd2+and Pb2+ in water using SA-DGT has also been studied.Research shows that yellow humic acid and EDTA has significantly effection on the measurement of Cd2+and Pb2+in water using SA-DGT.