In this study, two ion selective PVC membrane electrodes for determination of hafnium and cadmium ions were represented and characterized. Mesaldpt and Mebqb, as new ionophores, were used for determination of Hafnium and Cadmium, respectively. The proposed membrane sensors showed excellent discriminating ability towards mentioned ions with regard to several alkali, alkaline earth, transition and heavy metal ions. The hafnium selective electrode exhibited a Nernstian response for Hf 4+ over a wide concentration range (2.0´10 -7 -1.0´10 -1 M) with a slope of -15.1 mVdecade ?1 . The limit of detection was 1.9´10 -7 M. The electrode had a response time of 18 s, a lifetime of 1.5 months and a useful working pH range of 4.0–8.0. The cadmium sensor exhibited a Nernstian response for cadmium ions over a wide concentration range (1.0´10 -6 -1.0´10 -1 M) with a slope of -29.9 mV decade - 1 . The limit of detection was 8.0´10 -7 M. It had a fast response time of 8 s and could be used for at least 6 weeks in the pH range of 4.0 to 9.0 without any divergence in potential.
