PVC-based membranes of dicyclohexano-24-crown-8 as Cd(II) selective sensor

Membranes of dicyclohexano-24-crown-8 (I) as an ion-selective compound in poly(vinyl chloride) (PVC) based matrix have been tried for cadmium(II)-selective sensors. The effect of anion excluder, sodiumtetraphenylborate (NaTPB) and plasticizers dibutylphthalate (DBP), dioctylphthalate (DOP), di(butyl)butylphosphonate (DBBP), 1-chloronaphthalene (CN), tri-butylphosphate (TBP) and tris-(2-ethyl hexyl)phosphate (TEHP) on the performance of the membrane sensor has also been studied. It was observed that the membrane having the composition I: NaTPB:DBBP:PVC in the ratio 10:1:100:100 exhibited the best performance with a wide working concentration range of 3.0 × 10−5 to 1.0 × 10−1 M, a Nernstian slope of 30.0 ± 1.0 mV/decade of activity, and with a response time of 23 s. It was found selective to cadmium ions over a number of mono-, bi- and trivalent cations. The sensor works satisfactorily in the pH range of 2.0–5.4 and can successfully determine cadmium ions in partially non-aqueous medium having up to 40% (v/v) non-aqueous content. The sensor could be used as an indicator electrode in the titration of Cd2+ ions with EDTA.