A new cone shaped asymmetrically substituted calix[4]arene as an excellent ionophore in construction of Ag(I) ion-selective membrane electrode

A PVC membrane electrode for silver ion based on a new cone shaped calix[4]arene (CASCA) as membrane carrier was prepared. The electrode exhibits a Nernstian response for Ag + over a wide concentration range (1.0 x 10 - 1 -8.0 x 10 - 6 M) with a slope of 58.2 ′ 0.5 mV per decade. The limit of detection of the sensor is 5.0 x 10 - 6 M. The sensor has a very fast response time (∼5 s) in the concentration range of ≤ = 1.0 × 10 - 3 M, and a useful working pH range of 4.0-9.5. The proposed sensor displays excellent discriminating ability toward Ag + ion with respect to common alkali, alkaline earth, transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of Ag + with EDTA and in direct determination of silver ion in wastewater of silver electroplating.