Preparation and Study of Iodide Ion Selective Electrode Using a New Coordination Complex of Cobalt(Ⅱ) and meso-Tetrakis-(2-alkoxyphenyl)-porphyrin as Neutral Carriers

Coordination complexes of meso-tetrakis-(2-alkoxyphenyl)-porphrin (ROP)P with metal ions,i.e.Co(Ⅱ),Ni(Ⅱ) and Cu(Ⅱ) were prepared and their compositions were identified by elementary analysis.Ion selective electrodes were prepared by using the new complexes as neutral carriers,and composition of the electrode membrane was selected by the method of orthogonal testing.It was found that ISE using Co(Ⅱ)-(ROP)P as neutral carrier showed best potential response toward I--ion among the 3 complexes.Optimum potential response was attained in a phosphate buffer medium of pH 3.0.Approximate nernst response (at 25 ℃) was obtained in the range of 1.0×10-6-1.0×10-1mol·L-1 of I--ion with its detection limit (3S/N) of 8.0×10-7mol·L-1,and with its slope of -58.2 mV/dec.Electrochemical behavior and potential response mechanism of the electrode were studied by the UV-VIS spectroscopy and the AC impedance of the membrane.