Electrochemical Sensors Based On Nanomaterials For Simultaneous Determination Of Catechol And Hydroquinone

As the important industrial raw materials and synthetic intermediates, hydroquinone and catechol are widely used in chemical industry production. However, they are highly toxic to living beings. With the development of industry, hydroquinone and catechol have fouled environment to extraordinary degrees. What is more, due to their similar structures and properties, hydroquinone and catechol usually coexist in environment. Therefore, it is crucial to develop a simple and reliable analytical method for the accurate and simultaneous determination of hydroquinone and catechol. Among many other methods, electrochemical ensors have attracted significant interests owing to their excellent sensitivity and cheap equipment in this field.In this paper, the electrochemical sensors were fabricated and used to detect hydroquinone and catechol based on nanomaterials, such as graphene doped with B and N, Zn S/Ni S@Zn S quantum dots and multiwalled carbon nanotubes/polydopamine/gold nanoparticles. In addition, the proposed methods posess good performance, which were applied succefully to the simultaneous determination of hydroquinone and catechol in real water samples with satisfied results. The main work and results are as follows:1. Sensitive simultaneous determination of hydroquinone and catechol based on graphene doped with B and N and poly(alizarin red s)A highly sensitive electrochemical sensor for the simultaneous determination of catechol and hydroquinone was manufactured by electrochemical polymerization of alizarin red S onto graphene doped with B and N(BCN graphene) on a glassy carbon electrode using cyclic voltammetry. The composite film showed excellent electrocatalytic activity and reversibility towards the oxidation of both catechol and hydroquinone in 0.1 mol/L phosphate buffer solution(p H 6.5). Synchronously, the oxidation peak potentials of catechol and hydroquinone become separated by 101 m V, which ensured the anti-interference ability of the sensor and made simultaneous detection of catechol and hydroquinone possible in real samples. The peak currents increased linearly with their concentration over the range of 1.0 to 100 ?mol/L, and the detection limits for catechol and hydroquinone were 0.11 ?mol/L and 0.19 ?mol/L(S/N = 3), respectively. The developed sensor was successfully examined for real sample analysis with lake water and it showed a stable and reliable recovery data.2. Simultaneous determination of hydroquinone and catechol using a glassy carbon electrode modified with gold nanoparticles, Zn S/Ni S@Zn S quantum dots and L-CysteineWe describe an electrochemical sensor for simultaneous determination of hydroquinone and catechol. A glassy carbon electrode was modified with gold nanoparticles, L-Cysteine, and Zn S/Ni S@Zn S quantum dots using a layer-by-layer technique. The electrode materials were characterized by X-ray diffractometry, field emission scanning electron microscopy and by electrochemical impedance and fourier transform infrared spectroscopy. Cyclic voltammetry and differential pulse voltammetry revealed this modified electrode to represent a highly sensitive sensor for the simultaneous determination of hydroquinone and catechol. The anodic peak current for hydroquinone is related to its concentration in the 0.1 to 300 ?mol/L range(even in the presence of 0.1 mmol/L of catechol). The anodic peak current for catechol is related to its concentration in the 0.5 to 400 ?mol/L range(even in the presence of 0.1 mmol/L of hydroquinone). The detection limits(at an S/N ratio of 3) are 0.024 and 0.071 ?mol/L for hydroquinone and catechol, respectively. The modified electrode was successfully applied to the determination of hydroquinone and catechol in aqueous solutions and gave satisfactory results.3. Selective sensing of hydroquinone and catechol based on multiwalled carbon nanotubes/polydopamine/gold nanoparticles compositesIn this work, a highly sensitive and selective electrochemical sensor based on multiwalled carbon nanotubes/polydopamine/gold nanoparticles composites and chitosan was developed, which was used for simultaneous determination of hydroquinone and catechol derived from a large specific area of multiwalled carbon nanotubes and superexcellent electroconductibility of gold nanoparticles. It was found that hydroquinone and catechol could be completely separated on the electrode using cyclic voltammetry and differential pulse voltammetry technique under optimal conditions. The proposed sensor based on multiwalled carbon nanotubes/polydopamine/gold nanoparticles exhibited linear responses for hydroquinone and catechol from 0.1 to 10 ?mol/L with detection limits(S/N = 3) of 0.035 ?mol/L and 0.047 ?mol/L, respectively. In addition, the modified electrode was successfully implemented in the simultaneous determination of catechol and hydroquinone in tap and lake water samples. And compared with other methods, this sensor exhibited good sensitivity, stablilty and reproducibility.