Sulfate is a major anion with relevance to industrial chemistry, environmental chemistry including pollution studies, biochemistry and mineralogy, as well as several other areas. The fact that sulfur in several other forms is ultimately determined after conversion to sulfate further enhances the importance of sulfate determination. Acid rain is a very serious problem closely connected with the fast development of industries and economics in the world. In order to clarify and evaluate the effect of acid rain on the acidification of the natural environment, the development of chemical sensors for measuring the primary components of acid rain is important.Among chemical sensors ion-selective electrodes (ISEs) are mainly used for routine applications because they have a number of advantages over other methods of ion determination, such as analysis speed, portability, no sample destruction, and a wide measuring range. The essential property of ISEs is their selectivity, except for cases in which they are employed as detectors in connection with a separation method. In such a case, the best performance does not require selectivity, but only a short response time.Although the majority of the approximately 60 ions for which ionophore based polymeric membrane ion-selective electrodes have been described up to now are cations, 1,2 a series of a new anion-selective electrodes were introduced recently as a result of the growing interest in the host-guest chemistry of anions. [3][4][5] Classical liquid membrane electrodes for anions are based on quaternary ammonium salts and exhibit the Hofmeister selectivity sequence based on the analyte lipophilicity. 6,7 Recently, a series of new anion-selective electrodes has been described, which display a selectivity deviating from the Hofmeister sequence as a result of unique interactions between the carriers and the anions. It has been well documented that the selective complexation of anions by synthetic ionophores can be used to design anion selective electrodes. For sulfate, so far, the most promising ISE is based on a bis(thiourea) derivative that forms four hydrogen bonds in a 1:1 complex with sulfate. 8 Recently, a bis(imidazole) derivative was reported to exhibit a similar selectivity for sulfate with respect to major interferences along with a strong pH dependence. 9 The synthetic hydrotalcite have been used as ionophore for sulfate. 10 For a truly anion-selective electrode, a strong interaction between the ionophore and the anion is required in order to complex the anion in a selective fashion. The potentiometric response of the membranes doped with these complexes is believed to be based on the coordination of analyte anion axial ligand to the metal center of the carrier molecule. 11,12 Recently, we have used ionophores in the construction of ISEs for NO3 -13,14 and SCN -. 15 In the present paper, we report the use of N,N′-bis(2-amino-1-oxo-phenelenyl)phenylenediamine copper(II) as an excellent ionophore for the preparation of a high selective ISE for the potentiometric det...
