Determination of Selectivity Coefficients of Sodium and Potassium Ion-Selective Electrode Using Porous Silicon N-Type (100) Based Extended Gate Field Effect Transistor

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Ion-selective electrode (ISE) was able to accurately detect the ions, precisely for laboratory analysis purposes. The selection of the material varies to select a particular ion, according to the electrode response, and the decisive factor for the optimal selection of ISE for specific ion is the selectivity coefficient. This study used porous silicon (PSi) (100) as an ISE based on extended gate field effect transistor (EGFET) to characterize the selection's preference for sodium (Na+) as a target ion and potassium (K+) is an interference ion. The potential response in the linear region of the EGFET sensor between the detection electrode (PSi) and a reference electrode Ag/AgCl was measured in NaCl, KCl, and a mixed solution of the two salts along ions’ concentration (10-4-1 M) under drain-source voltage 0.3 V at temperature room. The potentiometric selectivity coefficient was calculated by two methods: (1) separate solution method (SSM) at the same activity (0.1 M) and (2) two solution method (TSM). The SSM method, KpotNa,K was 0.581, while the result of TSM method was 0.743. The results showed a slight superiority of Na+ selectivity and acceptable interference resistant for K+.