New insight for simultaneous determination of hazardous dihydroxybenzene isomers at crown ether modified polymer/carbon nanotubes composite sensor

A new insight is presented in the fabrication of a reliable electrochemical sensor for di-hydroxybenzene isomers; hydroquinone (HQ), catechol (CC), and resorcinol (RC) which have been considered as common pollutants in environment and water samples. The sensor is based on modifying the glassy carbon electrode (GC) with successive layers, multi-walled carbon nanotubes (CNT), poly-hydroquinone (PHQ) and benzo-12-crown-4 (CE); GC/CNT/PHQ/CE. CE is introduced for the first time as a receptor for the di-hydroxybenzene isomers based on host-guest size matching. Other cycling compound with different cavity diameter as beta-cyclodextrin (beta-CD) (6.0-6.5 angstrom) was examined displaying lower current responses. CE exhibited fit cavity size (1.20-1.50 angstrom). Thus, the inclusion complexes formed between beta-CD and di-hydroxybenzene isomers are less stable. The layered sensor showed highly electro-catalytic activity for simultaneous determination of isomers; HQ, CC and RC in the concentration ranges of 0.03-100 mu M, 0.01-100 mu M and 0.05-100 mu M with low detection limit values of 0.156 nM, 0.118 nM and 0.427 nM, respectively. The practical impact of the sensor was illustrated for determination of di-hydroxybenzene isomers in real water matrices from two different sources. Moreover, anti-interference ability of the layered sensor for determination of di-hydroxybenzene isomers was successfully achieved in presence of common interfering ions and organic pollutants.