Cobalt(II)-selective membrane electrode based on a recently synthesized benzo-substituted macrocyclic diamide

A PVC-membrane electrode based on a recently synthesized 18-membered macroc yclic diamide is presented. The electrode reveals a Nernstian potentiometri c response for Co2+ over a wide concentration range (2.0 x 10(-6) - 1.0 x 1 0(-2) M). The electrode has a response time of about 10 s and can be used f or at least 2 months without any divergence. The proposed sensor revealed v ery good selectivities for Co2+ over a wide variety of other metal ions, an d could be used over a wide pH range (3.0 - 8.0). The detection limit of th e sensor is 6.0 x 10(-7) M. It was successfully applied to the direct deter mination and potentiometric titration of cobalt ion.