NEUTRAL CARRIER AND ORGANIC RESIN-BASED MEMBRANES AS SENSORS FOR URANYL IONS

Uranyl ion selective electrodes have been constructed from poly(vinyl chloride) matrix membranes containing neutral carrier, 2,3,11,12-dicyclohexano-1,4,7,10,13,16-hexaoxacyclooctadecane and organic resin, 2,4-dihydroxypropiophenoneoxime-formaldehyde using dibutyl phthalate and dioctyl phthalate as plasticizing solvent mediators. These electrodes demonstrate linear response to UO22+ ions in the concentration range 10(-5)-10(-1) mol l(-1) with a Nernstian or near Nernstian slope at pH 3. The electrodes are inert towards acids, salt solutions and non-aqueous media for a period of 3 months and exhibit a response time as fast as 30 s. The electrodes with plasticizers have been found to be better compared with electrodes without plasticizers. The electrodes are sufficiently selective over a large number of bivalent and trivalent cations including calcium, iron(III) and copper(II), with selectivity coefficient values of the order of 0.01 for bivalent and 0.001 for trivalent cations. Monovalent ions cause interference at higher concentrations with selectivity coefficient values of the order of 0.1. The electrodes work satisfactorily in a partially non-aqueous medium.