Cobalt(II) ion-selective electrode with solid contact

A new all plastic sensor for Co(2+) ions based on 2-amino-5 (hydroxynaphtyloazo-1')-1,3,4 thiadiazole (ATIDAN) as ionophore was prepared. The electrode exhibits a low detection limit of 1.5 x 10(-6) mol L(-1) and almost theoretical Nernstian slope in the activity range 4.0 x 10(-6)- 1 x 10(-1) mol L(-1) of cobalt ions. The response time of the sensor is less than 10 s and it can be used over a period of 6 months without any measurable divergence in potential. The proposed sensor shows a fairly good selectivity for Co(II) over other metal ions. The electrode was successfully applied for determination of Co(2+) in real samples and as an indicator electrode in potentiometric titration of Co(2+) ions with EDTA.