Electrochemical sensing of iron (III) by using rhodamine dimer as an electroactive material

The voltammetric and potentiometric sensors based on a novel electroactive rhodamine dimer (RD) have been developed for the determination of Fe (III) ions. The RD exhibits two anodic peaks at 0.5 V and 0.7 V vs. Ag/Ag(+) within the potential range of 0.2-1.2V, which on addition of Fe (III) ions get converted to single anodic peak with a shift toward more positive potential of 0.9 V vs. Ag/Ag(+) due to the formation of Fe (III)-RD complex. The voltammetric sensor has been found to work well in the concentration range of 1.5 × 10(-5)-3.5 × 10(-4)M with the detection limit of 3.3 × 10(-6)M. Further, the potentiometric response of proposed PVC based solid contact coated graphite electrode (CGE-1) was linear for Fe (III) ions in the concentration range of 1.0 × 10(-1)-1.0 × 10(-7)M. The electrode showed a slope of 18.8 mV/decade with a detection limit of 4.68 × 10(-8)M for Fe (III) ions. Both of the sensors revealed good selectivity towards Fe (III) ions in comparison to various diverse metal ions. The analytical utility of the proposed sensors has been confirmed by the estimation of the Fe (III) content in different sample matrices.