Abstract
The performance of silver metal complexes with meso-tetraphenylporphyrin ([H2T(4-CH3)]PP) as ionophores for ion-selective electrodes was studied. The electrode exhibited linear response with Nernstian slope of 59.2 ± 1.0 mV per decade within the concentration range of 1.0 × 10-7 - 1.0 × 10-1 M silver ions. The limit of detection as determined from the intersection of the extrapolated linear segments of the calibration plot, was 1.0 × 10-7 M. The response time of the electrode was < 10 s over the entire concentration range. The silver-selective electrode exhibited good selectivity for Ag(I) with respect to alkali, alkaline earth and heavy metal ions. The electrodes could be used at least three months without a considerable divergence in their potential. The electrodes are suitable for use in aqueous solutions in a wide pH range of 3.0 - 9.0. They were used as indicator electrodes in titration of Ag(I) with sodium iodide solution and were successfully applied to direct determination of silver in real samples.
