Highly thiocyanate-selective membrane electrodes based on the N,N'-bis-(benzaldehyde)-glycine copper(II)complex as a neutral carrier

摘要

Some novel PVC membrane electrodes based on N,N'-bis-(benzaldehyde)-glycine metallic complexes of Cu(II),Ni(II),Zn(II)and Co(II)as neutral carriers are described.The results showed that the electrode based on the N,N'-bis-(benzaldehyde)-glycine copper(II)complex [Cu(II)-BBAG] had a near-Nernstian response to the thiocyanate ion ranging from 1.0x 10~(-1)to 9.0x 10~(-7)M in a phosphate buffer solution of pH 4.0 with a detection limit of 7.0x 10~(-7)M and a slope of-57.6 mV/decade at 25deg C.The electrode displays an anti-Hofmeister selectivity sequence in the following order:SCN > C1O_4 > Sal~-> I~-> Br~-> NO_2 > NO_3~-> SO_3~(2-)> SO_4~(2-)> Cl~-> H_2PO_4~-.The response mechanism is discussed in view of both AC impedance and UV spectroscopy techniques.The [Cu(II)-BBAG]-based electrode was successfully applied to the determination of the thiocyanate ion in wastewater and human saliva.