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Determination of sodium ions using a selective electrode (potentiometry)

Constitution of the electrode

The electrode selective to Na+ ions is similar in its design to the standard glass electrode (selective to H+) but without an internal reference electrode. It needs to be combined with an external reference electrode (e.g. Ag/AgCl). However, the composition of the glass is different: here it is composed of 71% of SiO2, 18% of Al2O3 and 11% of Na2O. This composition makes it selective to Na+ ions.

Table showing the composition of the glass according to the detected ion.
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