Thiocyanate-selective membrane electrode based on (octabromotetraphenylporphyrinato)manganese(III) chloride

Abstract

The response characteristics of a new solvent-polymeric membrane electrode with unique selectivity and detection limit toward SCN- ion are reported. The electrode is prepared by incorporating (octabromotetraphenylporphyrinato)manganese(III) chloride into a plasticized PVC-membrane. The resulting sensor exhibits anti-Hofmeister selectivity pattern with high specificity for thiocyanate over other anions, including lipophilic inorganic anions. The electrode has a linear dynamic range between 1.0 and 4.8 × 10-7M, with a Nernstian slope of 58.3±0.8mV/decade and a detection limit of 3.2 × 10-7M. The electrode can be used for at least 3 months without any considerable divergence in potential. It was used as an indicator electrode in potentiometric titration of SCN-1 ion and in direct determination of thiocyanate in urine samples.