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

Abstract

2060-2063A 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% o-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 M 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 pH 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