Abstract
In this work, we are presenting an iron ion (Fe^3+^) potentiometric sensor based on functionalized ZnO nanorods with selective ionophore (18 crown 6). Zinc oxide nanorods with a diameter of about 100 to 150โ
nm and 1โ
ยตm in length were grown on gold coated glass. The selective Fe^3+^ ionophore sensor with highly aligned ZnO nanorods showed high sensitivity, acceptable selectivity, reproducibility and a stable signal response for detecting Fe^3+^. The potentiometric response of the Fe^3+^ sensor with functionalized ZnO nanorods versus a Ag/AgCl reference electrode was observed to be linear over a logarithmic concentration range from 10^โ5^โ
M to 10^โ2^โ
M. The detection limit of the proposed sensor was about 5โ
ยตM, which is lower than the normal blood concentration of Fe^3+^ which is about 10โ
ยตM and can be up to 30โ
ยตM. The sensitivity of the proposed Fe^3+^ sensor was found to be 70.2ยฑ2.81โ
mV/decade with a regression coefficient R^2^=0.99 and a response time less than 5โ
s. The functionalized ZnO nanorods sensor with selective iron ionophore has a life time greater than one month and has shown insignificant interference with other ions usually present in the human blood serum. The proposed sensor was used as an indicator electrode for potentiometric titration.