The Novel SCN-Ion-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 SCN^- ions. This membrane exhibits a linear stable response over a wide concentration range (1.0 x 10^-5 to 1.0 x 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 log...= -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 SCN^- ion 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. [ABSTRACT FROM AUTHOR]