Cadmium (II) ion sensing through p- tert -butyl calix[6]arene based potentiometric sensor

Poly (vinyl chloride) (PVC) based membranes containing p-tert-butylcalix [6] arene (I) in the molecular form as an electroactive material along with anion excluder sodium tetraphenyl borate (NaTPB) and plasticizer Di-Octyl phthalate (DOP) have been used to fabricate a new cadmium-selective sensor. Out of the various compositions, the best performance was exhibited by the membrane having I-PVC-NaTPB-DOP in the ratio 1:33:1:65 (w/w). The sensor works well in the concentration range 9.7×10−5 to 1×10−1moldm−3 with a near-Nernstian slope of 29.0±1mV/decade of activity. The working pH range of this sensor is 2.8 to 6.2 and its performance was found satisfactory up to 20% non-aqueous medium. It exhibits a fast response time of 35s and could be used for more than 4months without any considerable change in response characteristics. It has excellent selectivity for Cd(II) over alkali, alkaline and other heavy metal cations.