▎ 摘　　要

An excellent electrocatalytic activity, repeatability and stability of electrochemical sensor for formalin detection was fabricated based on a homogeneous distribution of ellipsoidal palladium nanoparticle (PdNPs) on poly (acrylic acid)-functionalized graphene oxide (PAA-GO) modified on a glassy carbon electrode (GCE) (PdNPs-PAA-GO/GCE) with incorporated flow injection amperometry (FI-Amp). Homogeneous distribution of ellipsoidal palladium nanoparticles (PdNPs) were dispersed on PAA-GO via an electroless deposition method. The surface morphology and electrochemical behavior of the PdNPs-PAA-GO/GCE were characterized by transmission electron microscopy, fourier transform infrared spectroscopy, cyclic voltammetry and amperometry. The PdNPs-PAA-GO/GCE exhibited excellent electrocatalytic activity toward formalin oxidation. Then this modified electrode was incorporated with FI-Amp for formalin sensor development. In order to obtain good analytical performances, many parameters such as the amount of PdNPs-PAA-GO, applied potential, flow rate and sample volume were optimized. Under optimal conditions, this sensor provided a wide linear range, 50-50,000 mmol L-1, with high sensitivity (320 mA mmol L-1 cm(-2)). The limit of detection and limit of quantitation were 16 mmol L-1 and 53 mmol L-1, respectively. This proposed sensor exhibited good repeatability (RSD <3.5%), excellence stability (RSD = 1.5%, n = 500) and high sample throughput (60 samples h(-1)). This method was applied to the determination of formalin in soaked fresh food samples with satisfactory recovery. (C) 2017 Elsevier Ltd. All rights reserved.