Electrocatalytic oxidation and nanomolar detection ofhydrazine by luteolin electrodeposited at a multi-walled carbon nanotube and ionic liquid composite modified screen printed carbon electrode

Abstract

A new electrode was fabricated by electrodepositing luteolin at a screen printed carbon electrode (SPCE) modified with a composite of multi-walled carbon nanotube (MWNT) and ionic liquid (IL). Cyclic voltammograms of the modified electrode in phosphate buffer solution showed a pair of stable and reversible redox couple of luteolin with surface confined characteristics. This electrode possessed excellent electrocatalytic ability towards hydrazine oxidation. The overpotential was decreased significantly and the peak current was increased dramatically compared to those at bare SPCE. This enhancement of the responses was mainly contributed to the combination of the unique electrocatalytic and electronic properties of luteolin, MWNT and IL. The modified electrode was employed to the amperometric detection of hydrazine at an applied potential of 0.31 V vs. SCE with fast response, high sensitivity, good stability and reproducibility. Two linear ranges of hydrazine were from 2.0 × 10⁻⁸ to 2.0 × 10⁻⁷ M and from 2.0 × 10⁻⁷ to 1.2 × 10⁻⁴ M. Nanomolar detection limit of 6.6 × 10⁻⁹ M (S/N = 3) could be obtained, which is at least one magnitude lower than any others with electrochemical detection of hydrazine. The proposed method was also used to determine hydrazine residues in spiked drinking water and river water with average recoveries of 101.7% and 101.1%, respectively.