Influence of plasticizer, and metallic and graphite conducting substrate on the characteristics of a poly(vinyl chloride) membrane coated wire calcium lon-selective electrode
Poly(vinyl chloride) membrane-based calcium ion-selective electrodes have been constructed, with calcium bis(2-ethylhexyl) phosphate as a sensing material and tetrahydrofuran as solvent. The influence of several plasticizers and conducting substrates on the analytical characteristics (slope, interval response, lifetime and response time) of the electrodes was studied. The best characteristics were obtained with a graphite–poly(tetrafluoroethylene) conducting substrate of the Růžička type and with tributoxyethyl phosphate and o-nitrophenyl octyl ether as plasticizers. Chemical interference from several inorganic cations was also investigated. The analytical performance of the electrodes investigated was strongly dependent on a suitable combination of plasticizer and conducting substrate.