Highly sensitive and simultaneous determination of hydroquinone and catechol at poly(thionine) modified glassy carbon electrode

Abstract

A simple and highly sensitive electrochemical method for the simultaneous and quantitative detection of hydroquinone (HQ) and catechol (CT) was developed, based on a poly(thionine)-modified glassy carbon electrode (GCE). The modified electrode showed excellent electrocatalytic activity and reversibility towards the oxidation of both HQ and CT in 0.1M phosphate buffer solution (PBS, pH 7.0). The peak-to-peak separations (ΔEp) between oxidation and reduction waves in CV were decreased significantly from 262 and 204mV at the bare GCE, to 63 and 56mV, respectively for HQ and CT at the poly(thionine) modified GCE. Furthermore, the redox responses from the mixture of HQ and CT were easily resolved in both CV and DPV due to a difference in the catalytic activity of the modified GCE to each component. The peak potential separation of ca. 0.1V was large enough for the simultaneous determination of HQ and CT electrochemically. The oxidation peak currents of HQ and CT were linear over the range from 1 to 120μM in the presence of 100 and 200μM of HQ and CT, respectively. The modified electrode showed very high sensitivity of 1.8 and 1.2μAμM−1cm−2 for HQ and CT, respectively. The detection limits (S/N=3) for HQ and CT were 30 and 25nM, respectively. The developed sensor was successfully examined for real sample analysis with tap water and revealed stable and reliable recovery data.