The NAS11-8 glass electrode is utilized as a selective sodium ion sensor. However, it is easily spoiled by biomaterials in sample solutions. Bis(12-crown-4), a sodium ionophore, is 100 times more selective for sodium than potassium in the PVC electrode using NPOE as a plasticizer. The same selectivity for sodium over potassium is reported when Bis(12-crown-4) is used on a coated wire electrode. It can be used in either a liquid membrane or a PVC membrane. TFPB, a lipophilic anion, can help improve detection sensitivity.
Ion selectivity: LogKpot(Na/Li):-3.0, LogKpot(Na/K):-2.0,
LogKpot(Na/Cs):-2.0, LogKpot(Na/Rb):-2.4, LogKpot(Na/NH4):-3.0,
LogKpot(Na/Ca):-4.0, LogKpot(Na/Ba):-3.7, LogKpot(Na/Sr):-3.7 Formulation: Ionophore: 6%, NPOE: 70%, TFPB: 50 mol% of ionophore
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