Determination Of Serum Potassium Ion By Solid-state Ion-selective Electrodes

Potassium?K?is an indispensable element in the human body.The normal range of potassium ion concentration in healthy adults is about 3.5-5.5 mM.Unbalanced K⁺ concentration in the heart can lead to abnormal myocardial contractility and symptoms of arrhythmia.Therefore,timely and accurate detection of blood potassium is extremely important for saving lives.Common methods for detecting K⁺include gravimetric method,ion chromatography and atomic absorption spectrometry.The stability of the internal reference potential compared to the classical liquid ion-selective electrodes will affect the stability of the ion-selective electrode potential response.The all-solid-state ion-selective electrode has simple and portable,low cost,it becomes a possible way.In this thesis,a solid-state ion selective electrode detection system based on different ion-electron transducing layers was constructed to improve the stability of sensing response,and the solid-state ion selective electrode was applied to the analysis and detection of potassium ions in goat serum samples.The content of the research mainly includes the following three parts:?1?Detrmination of Concentration Serum Potassium Ion Using All-Solid-State Potassium Ion Selective Electrode based on Two-Dimensional MnO₂ NanosheetsTwo-dimensional MnO₂ nanosheets were prepared by hydrothermal synthesis,and they were used as solid contact layers.A solid potassium ion selective electrode was constructed with valinomycin as an ion carrier to realize timely and accurate detection of potassium ions.The results show that using the MnO₂ nanosheet as the ion-electron transducing layer,the obtained potassium ion selective electrode exhibits lower electrical resistance and the potential stability is improved due to the rapid charge and discharge characteristics of manganese dioxide.In addition,the electrodes showed good stability in both aqueous test and anti-interference experiments.The linear response range of the electrode is 1.0×10^-5-1.0×10^-2mol/L,the detection limit is 6.3×10^-6 mol/L.?2?Detrmination of Concentration Srum Potassium Ion Using All-Solid-State Potassium Ion Selective Electrode based on GO/MnO₂ CompositeIn order to further improve the conductivity of the solid contact layer,we have superposed the graphene oxide and MnO₂ nanosheets by ultrasonic,and analyzed by electrochemical characterization to show that the GO/MnO₂ complex was obtained.The graphene oxide was reduced by electrochemical reduction to obtain rGO/MnO₂.The composite rGO/MnO₂ was used as the potassium ion selective electrode constructed by the solid contact layer.The solid ion selective electrode showed good stability in both the water layer test and the anti-interference test.The linear response range of the electrode is: 1.0×10^-5-1.0×10^-2 mol/L and the detection limit is 7.9×10^-6 mol/L.?3?Detrmination of Concentration Srum Potassium Ion Using All-Solid-State Potassium Ion Selective Electrode based on MoS₂/Fe₃O₄ CompositeIn order to further improve the capacitance of the solid contact layer,we prepared MoS₂/Fe₃O₄ composites by one-step solvothermal method.The SEM and TEM characterization of the composite MoS₂/Fe₃O₄ were carried out.The results showed that we successfully synthesized the MoS₂/Fe₃O₄ composites.The potassium ion selective electrode constructed with MoS₂/Fe₃O₄ as a solid contact laer showed good stability in both aqueous layer test and anti-interference test.The linear response range of the electrode is 1.0×10^-5-1.0×10^-2 mol/L,the detection limit is 6.3×10^-6 mol/L.The capacitance values of the solid contact layers of the above three materials as solid potassium ion selective electrodes were calculated by chronopotentiometry,and the capacitance values were 28.6?F,50?F and 77?F,respectively.