The Novel SCNIon-selective Electrode Based on the 1-Benzyl-3-(4-nitrophenyl) thio-urea Ionophore

A potentiometric sensor based on the 1-benzyl-3-(4-nitrophenyl) thio-urea was synthesized and tested as an ionophore in PVC based membrane sensor towards SCNions. This membrane exhibits a linear stable response over a wide concentration range (1.0 × 10 �5 to 1.0 × 10 �2 M) with a slope of �59.2 mV/dec., a detection limit of log(SCN � ) = �5.05, and a selectivity coefficient for thiocyanate against perchlorate anion of = �0.133. The selectivity series of the membrane is as follows: SCN � > ClO4 � > I � > NO3 � > HSO3 � > Cl � > HSO4 � > F � > CH3COO � > HCO3 � > Br � > H2PO4 � > SO3 2� > SO4 2� > CO3 2� . The proposed electrode showed good selectivity and a good response for the SCNion over a wide variety of other anions in pH 6.0 buffer solutions and has a fast response time of about < 5s. The influences of the membrane by pH, ionophore, and plasticizer were studied.