Charge-transfer complex between iodine and a new Schiff's base as anion-carrier in construction of a highly selective triiodide PVC-based membrane electrode

A highly selective triiodide membrane electrode based on a charge-transfer complex of bis(2-hydroxybenzophenone) butane-2,3-dihydrazone with iodine as an ion-carrier is presented. The electrode exhibits a Nernstian behavior over a wide triiodideions concentration range (1.0 x 10(-7)- 1.0 x 10(-1) M) with a detection limit of 7.0 x 10(-8) M. The response of the sensor is independent of the pH of solution in a wide pH range (2.0-12.0). The electrode shows a very short response time (< 5 s). It exhibits very good selectivity relative to a wide variety of inorganic and organic anions, including iodide, bromide, chloride, fluoride, nitrite, nitrate, sulfite, sulfate, cyanide, thiocyanate, and acetate. In fact, the selectivity of the proposed sensor shows great improvements compared to the previously reported electrodes for the triiodide ion. The proposed membrane sensor is very stable, and can be used for at least 6 months without any divergence in potential.