Construction Of Solid-state Potassium Ion Electrode And Its Application In Serum Potassium Ion Detection

Potassium is an essential element for the human body,mainly in the form of ions in cells.The concentration in serum is about 3.5–5.5mM.Many physiological activities of the human body can not be separated from potassium ions.In modern medicine,potassium ion level is one of the most important indicators of human electrolyte detection.Therefore,the accurate and rapid detection of potassium ion is very important.With the development of modern science and people’s living needs,the solid state ion selective electrode,which is based on the ionselective electrode,is expected to realize the rapid and convenient detection of serum potassium ions due to its easy preparation,storage and carrying.In this dissertation,based on the current research hotspot,we developed solid-state ion-selective electrodes with different transduction layer materials to detect serum potassium ion.The main research contents are as follows:（1）Through the method of electrodepositing manganese dioxide,the conductive layermaterial（MnO₂）is obtained directly on the electrode substrate in one step.There is no need for tedious material synthesis and post-painting steps,which can greatly shorten the experiment time and reduce the waste of experimental material resources and pollution.Using valinomycin as a potassium ion probe,and then the potassium ion selective electrode with electrodeposited manganese dioxide（MnO₂）as solid contact layer was designed by using valinomycin aspotassium ion probe.The electrode has a rapid response to potassium ion and shows goodpotential stability in various external interference and water layer tests.The response slpoe is54.1mV/decade（R²=0.988）in the range of 1.0×10^-4–1.0×10^-2 M,and the detection limit is 5.0×10^-5M.（2）According to the mechanism of electron-ion conversion of solid-state transfer layer,we need solid transducer with large capacitance to achieve high electrode potential stability and fast electrode response speed,,which is similar to the electrode material with largecapacitance,fast charge discharge and good cycle performance in the research of batteries.We used Mo S₂,Fe₃O₄,and graphene materials that are often used in battery materials to synthesize a conductive layer material with Fe₃O₄modified Mo S₂and r GO as the support respectively,and constructed a composite based on Fe₃O₄/rGO and Fe₃O₄/MoS₂.Solid state potassium ion electrode with solid contact layer.The two electrodes respond quickly topotassium ions,and show good potential stability in various external interferences and water layer tests,but there are big differences in linear response range,response slope and detection limit.Those electrodes were applied to the determination of potassium ion in goat serum,and the potential response was fast and stable.Compared with the results of atomic absorption spectrometry,the relative standard deviation of the method is less than 3%.The results show that those all-solid-state ion selective electrodes constructed in this paper can be used for the detection of serum potassium in real samples and have certain practical value.