Simultaneous determination of hydroquinone and catechol using covalent layer-by-layer self-assembly of carboxylated-MWNTs

A carboxylated multi-wall carbon nanotubes (CMWNTs) layer-by-layer (LBL) self-assembled film was prepared using ethylenediamine as an arm linker. Scanning electron microscopy (SEM) characterized the morphology of the LBL self-assembled film and Fourier transform infrared (FT-IR) spectroscopy confirmed the formation of covalent bond between CMWNTs and ethylenediamine. The electrochemical experiments indicated that the modified electrodes can simultaneously determinate hydroquinone (HQ) and catechol (CC). Differential pulse voltammetry (DPV) exhibited the oxidation peak current of HQ was linear to its concentration in the range of 10–120   μM with the detection limit of 2.3   μM in the presence of 0.1   mM CC, and at the same time the oxidation peak current of CC was linear to its concentration in the range of 5–80   μM with the detection limit of 1   μM in the presence of 0.1   mM HQ. Moreover, the CMWNTs modified electrode also showed excellent selectivity and stability.