Strontium-selective membrane electrodes based on some recently synthesizedbenzo-substituted macrocyclic diamides

Eight different recently synthesized macrocyclic diamides were studied to c haracterize their abilities as strontium ion carriers in PVC membrane elect rodes. The electrode based on 1,13-diaza-2,3;11,12-dibenzo-4,7,10-trioriacy clopentadecane-14,15-dione exhibits a Nernstian response for Sr2+ ions over a wide concentration range (1.0 x 10(-1)-3.2 x 10(-5) M) with a limit of d etection of 8.0 x 10(-6) M (0.7 ppm). The response time of the sensor is si milar to 10 s, and the membrane can be used for more than three months with out observing any deviation. The electrode revealed comparatively good sele ctivities with respect to many alkali, alkaline earth, and transition metal ions. It was used as an indicator electrode in potentiometric titration of carbonate ions with a strontium ion solution.