Highly Sensitive and Simultaneous Determination of Hydroquinone and Catechol at Thionine/Graphene Oxide Modified Glassy Carbon Electrodes

Abstract

A highly sensitive electrochemical method for the simultaneous and quantitative detection of hydroquinone (HQ) and catechol (CC) was developed, based on covalent immobilization of thionine (TH) by Schiff-base reaction between -NH 2 of TH and -COH onto graphene oxide modified glassy carbon electrodes (GO/GCE). The modified electrode showed excellent electrocatalytic activity and reversibility toward the oxidation of both HQ and CC in 0.1 M phosphate buffer solution (PBS, pH 7.0). The redox responses from the mixture of HQ and CC were clearly resolved in both cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with the peak differences of 100 mV and 110 mV, respectively. The oxidation peak currents of HQ and CC were linear over the range from 1 to 200 μM in the presence of 150 μM of counterpart. The detection limits (S/N = 3) for HQ and CC were 20 and 25 nM, respectively. Furthermore, the electrochemical performances with some interference were studied. The developed sensor was successfully examined for real sample analysis with tap water and revealed stable and reliable recovery data. Hydroquinone (HQ) and catechol (CC) are two dihydroxybenzene isomers and can be used in many fields, such as tanning, cosmetics, dye, chemical, and pharmaceutical industries.1 At the same time, they are considered as environmental pollutants by the US Environmental Protection Agency (EPA) and the European Union (EU) 2 due to their high toxicity and low degradability in the ecological system. They have similar basic quinine structures and coexist in environmental samples. Therefore, it is significant to establish simple andrapid analytical methods to detect them sensitively, selectively and simultaneously.At present, the main analytical methods to determinate HQ and CC are high performance liquid chromatography, 4 spectrophotometry, 5 electrochemiluminescence, 6 synchronous fluorescence 7 and electrochemical methods. However, the chromatographic method is complicated and generally takes quite a long time for a single analysis because of extra steps for pretreatment and separation before the signal detection. Optical methods usually require an additional reagent for the signal generation.8 Moreover, the actual effect of resorcinol on the chemiluminescence reaction is still unknown and affects the detection of HQ and CC.9 Therefore, electrochemical techniques, especially voltammetric methods, due to having more simplicity and selectivity are preferable over chromatographic and optical methods and more feasible for miniaturization of analysis.10-13 Till now, high degree of overlapping between their voltammograms is one of the main barricades for most conventional solid electrodes. Also, the use of unmodified electrodes for the detection of these compounds has a number of limitations such as slow electron transfer kinetics, low sensitivity and reproducibility over a wide range of solution compositions. Hence, it is pertinent to explore and develop a reliable method to fabricate modified electrodes with electron transfer medi...

Electrochemically Stimulated DNA Release from a Polymer‐Brush Modified Electrode

“…55 mV/pH, Figure 2B, inset. Theoretically, also confirmed experimentally 44, this slope corresponding to the 2e − /2H + reduction process of thionin should be 59 mV/pH. A little bit smaller slope of the E ° vs. pH dependence found in our system on the polymer‐modified electrode could originate from non‐complete reversibility of the thionin redox process, which is a known phenomenon for quinonoid redox species 45.…”

Simultaneous Determination of Hydroquinone and Catechol by Differential Alternative Pulses Voltammetry

“…The detection limit of the determinations, evaluated on the basis of S/N=3 was found to be 0.2 μmol L −1 for HQ and 0.5 μmol L −1 for CC. It is acceptable, compared with data reported in the literature, which show that the detection limits reached by applying DPV and modified electrodes vary in the range from 0.007 μmol L −1 to 50 μmol L −1 for HQ and from 0.009 μmol L −1 to 50 μmol L −1 for CC . Costly materials and complicated techniques for electrode modification were required to achieve lower limits of detection by DPV.…”

Sensitive and Simultaneous Determination of Hydroquinone and Catechol in Water Using an Anodized Glassy Carbon Electrode with Polymerized 2-(Phenylazo) Chromotropic Acid

“…However, the aforementioned methods possess disadvantages such as the requirement of sophisticated laboratories, well-trained instrument operators, an expensive instrument, complicated analysis procedures, and time-consuming preparations [4]. Meanwhile, various electrochemical methods have attracted increasing attention due to their high sensitivity, simple operation, fast response, and low cost [4,[15][16][17]. Many modifiers such as mesoporous Pt [18], RGO-MWCNT [19], graphene/AuNPs/chitosan [20], Pt-MnO 2 [21], carbon nanofragment [22], and conducting polymers (CPs) [23] have been introduced to enhance the electrode performance.…”