| Abstract: | An iron (III) ion selective PVC membrane electrode based on 1,7-dithia 12-crown-4 as a neutral carrier was prepared. Monovalent responses with a Nerstian slope of 56+1 mV/decade was observed for the Fe (III) ion-selective electrode within the concentration range 10?3–10?5 M Fe (NO3)3. The monovalent responses may be attributed to the formation of Fe (OH)2+ or Fe (OH)2(H2O)+4 species in aqueous solutions and the absorption of these ions into the PVC electrode membrane. The electrode exhibited good selectivity for Fe (III) in comparison with various alkali, alkali-earth and some heavy metal ions. The effects of the composition of the membrame, addition of STPB (sodium tetraphenyl borate), the concentration of internal solution of the electrode and anions in the test solutions were discussed. |
