Detection Of Multiple Heavy Metal Ions Based On Microchip Integrated With All-solid-state Ion Selective Electrodes

Heavy metals pollution is long-term,hidden and irreversible.The detection of heavy metal ions in environmental water plays a extremely important role in human health and environmental protection.In order to meet the requirement of rapid detection of heavy metal ions,this thesis proposed to develop all-solid-state ion selective electrodes.Design and prepare sensor chip,establish and optimize the detection method of sensor chip,and carry out application test research.Further research and development of detection device based on all-solid-state ion selective electrodes to achieve rapid detection of heavy metal ions.Main research work and results of this thesis:(1)Copper,zinc and nickel all-solid-state ion selective electrodes were prepared.The sensing efficiencies of three kinds of electrodes were tested.The conductive polymer PEDOT/PSS film was deposited on the surface of carbon electrode.Then,THF containing copper,zinc,nickel ion-carrier,plasticizer o-NPOE,ion exchanger Na TFPB and PVC were drop casted onto PEDOT/PSS membrane,respectively.After the evaporation of the THF,three kinds of all-solid-state ion selective electrodes of copper,zinc and nickel were prepared.The experiment optimized the deposition time of PEDOT/PSS conductive polymer,and the results showed that the PEDOT/PSS film with a deposition time of 714 s had the best performance.The effect of Na TFPB on the performance of the all-solid-state copper ion selective electrode was investigated.It was found that the detection limit of the all-solid-state copper ion selective electrode decreased from 1×10-5mol.L-1 to 1×10-6mol.L-1 when Na TFPB with mass fraction of 2.1%was added to the copper ion selective membrane.The detection range of all-solid-state copper ion selective electrode was 1×10-6mol.L-1 ~1×10-2mol.L-1.The detection range of all-solid-state zinc and nickel ion selective electrodes was 1×10-5mol.L-1~1×10-2mol.L-1.All-solid-state copper,zinc and nickel ion selective electrodes had good reproducibility and selectivity.(2)A screen-printed electrode array was designed and developed,which integrated all-solid-state copper,zinc,nickel ion selective electrodes and all-solid-state reference electrode.All-solid-state copper,zinc and nickel ion selective electrodes were prepared by modifying conductive polymer PEDOT/PSS membrane and ion selective membrane on carbon conductive substrate.All-solid-state reference electrode was prepared by modifying PVC polymer film containing ionic liquid on silver/silver chloride conductive substrate.The potential response difference of the all-solid-state ion selective electrode of the same batch was within 7m V.The potential stability of the prepared all-solid-state reference electrode was good.During the detection of 4 hours,the potential variation value was 1-2m V,and the electrode was not sensitive to copper,zinc and nickel ions.(3)The sensor chip for detecting copper,zinc and nickel ions was designed and developed.Based on the prepared screen-printed electrode array,combined with the microfluidic technology,a composite chip of PET-PDMS with microcavity and microchannel structure was designed and fabricated.The prepared composite chip was used to simultaneously detect copper,zinc and nickel in the mixed solution.The experimental results showed that the sensor chip can detect copper,zinc and nickel ions in solution simultaneously.(4)A multi-channel open-circuit potential signal detection circuit based on the above mentioned sensor chip was constructed,and a potential detection system for copper,zinc and nickel ions based on the all-solid-state ion selective electrode was established.The system can measure two potential signals at the same time,and the potential difference was about 2m V compared with the Chen Hua electrochemical workstation.