Zn2+ sensor based on Zn-bis(2,4,4-trimethylpentyl)dithiophosphinic acid complex in PVC matrix

A zinc complex of the organic ion exchanger, bis(2,4,4-trimethylpentyl) dithiophosphinic acid, has been used as an electroactive material for the preparation of PVC-based Zn2+-selective electrodes. The PVC matrix incorporating sodium tetraphenylborate (NaTPB) as the anion excluder and dibutyl(butyl)phosphonate (DBBP) as the solvent mediator along with the above complex in the ratio 7:29:5:59 (Zn-Cyanex-301:DBBP:NaTPB:PVC) exhibited a working concentration range of 2.8 x 10(-5)-1.0 x 10(-1) M, with a slope of 30.1 mV per decade of activity and a fast response time of 15 s. The valid pH range for the membrane sensor is 2.1-6.9 and it can also be used in partially non-aqueous medium having upto 10% (v/v) non-aqueous content. The;sensor exhibits good selectivity over a number of other cations and has been applied as indicator electrode in the potentiometric titration of Zn2+ against EDTA for the determination of end point. (C) 1998 Elsevier Science Ltd. All rights reserved.