▎ 摘　　要

Herein, we have described a simple electrochemical method for the deposition of the calcium ions cross linked pectin film (CCLP) along with gold nanoparticles (GNPs) on the graphene (GR) modified glassy carbon electrode (GCE) and applied for the determination of hydrazine. The formation of composite film was confirmed by cyclic voltammetry, scanning electron microscopy, Energy-Dispersive X-ray spectroscopy and X-ray diffraction studies. The GR/CCLP-GNPs/GCE film exhibited significantly enhanced electro catalytic ability towards oxidation of hydrazine. The kinetic parameters such as electron transfer coefficient (alpha) and diffusion coefficient (D-o) for the hydrazine oxidation were determined as 0.46 and 2.91 x 10(-6) CM2 S-1, respectively. Two linear ranges were observed in the amperometric determination of hydrazine: (1) 10-600 nM with sensitivity of 47.6 nAnM(-1) cm(-2) and (2) 0.6-197.4 mu M with sensitivity of 1.786 mu A mu M-1 cm(-2). The sensor is able to detect trace level of hydrazine in nanomolar range with very low deletion limit (LOD) of 1.6 nM. This is the lowest LOD achieved compare to all the reported electrochemical amperometric sensors so far. In addition, the sensor is able to detect hydrazine even in the presence of 500 folds excess quantity of interfering ions present in the water and biological liquid. The practicality of the proposed sensor has been demonstrated in water and urine samples. Other advantages of the sensor are repeatability, reproducibility and stability. (C) 2014 Elsevier Ltd. All rights reserved.