Electrochemical impedance spectroscopy as a transduction method for electrochemical recognition of zirconium on gold electrode modified with hydroxamated self-assembled monolayer

A new modified electrode is reported for the determination of zirconium ion (Zr(IV)) based on (i) in-situ functionalization of gold cysteamine self-assembled monolayer by nitrilotriacetic acid, and its further modification of by hydroxylamine hydrochloride as a recognition system, and (ii) electrochemical impedance spectroscopy (EIS) as a transduction method. Zr(IV) was selectively accumulated on the topside of hydroxameated surface, and the surface blocked the charge transfer process between metallic base and a redox probe in solution. The EIS complex plane plots showed a drastic change in the charge transfer resistance of the probe redox reaction as a function of Zr(IV) concentration. This behavior was used for construction of the calibration curve, and a linear range from 1.0 × 10−9 to 5.0 × 10−5 M Zr(IV) with a detection limit of 7.8 × 10−10 M and a relative standard deviation (RSD) of 1.79% for n = 5 at 5.0 × 10−5 M Zr(IV) was observed. The validity of the method and applicability of the sensor were successfully tested by determining Zr(IV) in synthetic as well as natural waters (tap and river waters) without interference from sample matrix.