Low cost, trouble-free disposable pencil graphite electrode sensor for the simultaneous detection of hydroquinone and catechol

This work proposes, one of the simplest methods for the modification of pencil graphite electrode (PGE) using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The electrochemical modification (pre-treatment) of the PGE was carried out in 0.1 M NaOH using CV technique by applying a potential in between-0.4 V and 1.4 V. In the presence of phosphate buffer (scan rate-50 mV s(-1), 0.2 M, pH similar to 7.4), the active surface of the pre-treated pencil graphite electrode exhibits improved sensing properties towards the determination of catechol (CC) and hydroquinone (HQ) with improved sensitivity and reproducibility. Sensing characteristics were evaluated under various experimental conditions (scan rate, analyte concentration, interference study & pH variation) for HQ and CC using pre-treated pencil graphite electrode (PPGE). Scan rate dependent sensing study shows that the electrode process is diffusion-controlled at the modified electrode. The pre-treated pencil graphite electrode showed the lower detection limits for HQ and CC is 0.85 mu M & 0.59 mu M respectively with a wide linear range (HQ: 0.4 to 1.2 x 10(-4) M, CC: 0.1 x 10(-4) M to 0.7 x 10(-4) M). Experimented pre-treated pencil graphite electrode was used and tested for the water from house hold tap which also showed high sensitivity towards HQ and CC.