A polymeric membrane ion selective electrode based on organic-inorganic composite ion exchanger for the determination of thorium(IV)

Abstract

A poly(vinyl chloride) membrane electrode based on organic-inorganic composite ion exchanger, tin(IV) tungstoselenatepyridine, has been prepared and tested for the selective

determination of thorium(IV) ions. The PVC membrane electrode comprising 16% composite ion exchanger as the electroactive phase, 50% <i>o</i>-dioctyl phthalate as plasticizer, 4% tetraphenyl borate as anionic excluder and 30% poly(vinyl chloride) displays a linear response to thorium(IV) ions over a wide concentration range of 1.0×10^-1-8.0×10^-6 <i>M </i>with a Nernstain slope of 14.2 mV/ decade. The electrode shows a very short response time (~15 s)

and may be used in the <i>p</i>H range 2.5-9.0. The selectivity coefficient for alkali, alkaline earth and transition is smaller than 4.0×10^-4. The sensor has been successfully used as an indicator

electrode in the potentiometric titration of Th⁴⁺ with EDTA as well as also for the determination of Th⁴⁺ in the binary mixtures.