A polyvinylchloride-based cadmium ion-selective electrode using [Mo₂(OAc)₂(H₂-calix[4]arene)] as an electroactive material.

A highly electroactive material [Mo₂(OAc)₂(H₂-calix[4]arene)] is used as a neutral carrier for Cd²+ ions in this paper. The membrane is fabricated by using ionophore [Mo₂(OAc)₂(H₂-calix[4]arene)]:poly(vinyl chloride) (PVC): dibutylphthalate(DBP):sodium tetraphenyl borate (NaTPB) in the ratio of 40:300:470:5 respectively and tetrahydrofuran (THF) used as a solvent. The membrane electrode performed in the concentration range of 9.9 x 10⁻⁸-1.0 x 10⁻¹ M (2.34 x 10⁻⁵-23.64 mg/mL) having the Nernstian slope of 30.0±1.0 mV and the best detection limit was observed at 9.8 x 10⁻⁸ M (2.31 x 10⁻⁵ mg/mL). The proposed membrane electrode has the response time of 12 s and a useful working pH range of 1.0-7.0, and used over a period of 10 months and work satisfactorily in the test solution having 30% (v/v) non-aqueous content. Electrode sensor has distinguishable ability for Cd²+ ion with regard to several alkali, alkaline earth, transition and heavy metal ions. It was used in direct potentiometry as an indicator electrode, in the potentiometric titration of 10⁻³ M Cd²+ solution against 10⁻² M of ethylenediaminetetraacetic acid (EDTA).