Silver(I)-selective electrode based on Bz(2)Oxo(4)(18)dieneS(4) tetrathia macrocyclic carrier

摘要

A polystyrene-based membrane of 7,8: 16,17-dibenzo- 6,9,15,18-tetraoxo- 1,5,10,14-tetrathiacyclooctadeca-7,16- diene Bz(2)Oxo(4)(18) dieneS(4) was fabricated using sodium tetraphenylborate (NaTPB) and dioctyl phthalate (DOP) as anion excluder and plasticizing agent. The best performance was obtained from the membrane with the composition ionophore Bz(2)Oxo(4)( 18) dieneS(4): polystyrene: DOP: NaTPB, 5: 100: 150: 10 (w/w). The response of the electrode was linear over a wide range of concentration, 1.26 x 10(-6) - 1.00 x 10(-1) mol L-1 for silver ion with a Nernstian slope of 58.4 +/- 0.1 mV per decade and a detection limit of 1.0 x 10(-6) mol L-1. The electrode was found to be chemically inert and of adequate stability with a response time of 10 s and could be used for a period of 3 months without change of potential. It worked satisfactorily in mixtures containing up to 35 (v/v) non-aqueous content. The proposed membrane sensor had good selectivity for Ag+ over a wide variety of metal ions in the pH range 2.2 - 8.5. It was successfully used as an indicator electrode in potentiometric titration of silver ion. The electrode was also useful for determination of Ag+ in waste from photographic films.