Copper ion selective membrane electrodes based on some Schiff base derivatives

A series of Schiff base derivatives were studied to characterize their abilities as a copper ion carrier in PVC membrane electrodes. The electrode based on 2,2'-[4,4'diphenyl-methanebis(nitrilomethylidyne)]-bisphenol exhibits a Nernstian response for copper ions over the activity range 8.0 x 10(-6) - 1.0 x 10(-1) mol L-1 with detection limit of about R mol L-1 of copper ion in comparison with two other Schiff bases. The response time, pH effect and other characteristics of the electrodes were studied in a static mode. The effect of the methyl group substitute on Schiff base structure with -SO2 bridging group in different positions with respect to -OH group was studied. The results show that behavior of the electrodes is not considerably influenced by the position of methyl substitute. The selectivity coefficients were determined with modified fixed interference method (FIM) and matched potential method (NIPM). 'Me proposed electrodes comparatively show good selectivity with respect to alkali, alkaline earth and some transition metal ions. The electrodes were used for the determination of copper in black tea, multivitamin and mineral capsule and as an indicator electrode in potentiometric titration of copper ion.