A SELECTIVE MEMBRANE ELECTRODE FOR THIOCYANATE ION BASED ON A COPPER-1,8-DIMETHYL-1,3,6,8,10,13-AZACYCLOTETRADECANE COMPLEX AS IONOPHORE

Abstract

An ion selective electrode for thiocyanate based on Cu(II)-1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane complex as an ionophore is described. At pH 4.5–10.5, the electrode based on this ionophore and cationic sites (40 percent of the ionophore) responds to thiocyanate in linear (E vs log [SCN⁻]) range from 1.0 × 10⁻¹ to 7.0 × 10⁻⁶ M. Selectivity coefficients determined with the match potential method (MPM) indicate that interference from inorganic and organic anions is very small. The proposed sensor shows a fast response time of about 15 s. It was applied as an indicator electrode in titration of thiocyanate with Ag⁺ and in potentiometric determination of thiocyanate in saliva and urine samples.

Keywords:

• Potentiometry
• Ionophores
• Thiocyanate selective electrode
• PVC membrane
• Urine
• Saliva
• Cu(II)-1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane complex

ACKNOWLEDGMENTS

The support of this work by the Research Council of Tehran University is acknowledged.