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In this work, manganese‐based metal‐organic frameworks (MnBDC) were synthesized by solvothermal method and physically mixed with pre‐prepared graphene oxide (GO) to obtain GO/MnBDC, which were calcined to give MnO@C composite coated with reduced graphene oxide (rGO) marked as rGO/MnO@C. The materials were characterized by SEM, XRD, FTIR and XPS. Based on this composite, a novel sensor was constructed on a glassy carbon substrate, which exhibited good electrocatalytic activities to the redox reactions of catechol (CC) and hydroquinone (HQ), enabling simultaneous detection of both analytes. Under optimized conditions, the electrochemical sensor demonstrated a linear range of 0.50–90.00 μM for both CC and HQ detection, with respective detection limits of 0.05 μM and 0.03 μM. Moreover, the sensor exhibited excellent sensitivity, selectivity and accuracy for detecting CC and HQ simultaneous in real samples. [ABSTRACT FROM AUTHOR]

This paper reports a dual immunosensor for the simultaneous determination of two important fertility‐related hormones: 17β‐estradiol, E2, and follicle‐stimulating hormone, FSH. The implemented method involves direct competitive (E2) or sandwich‐type (FSH) immunoassays carried out on magnetic microparticles (MBs) and amperometric detection at screen‐printed dual carbon electrodes (SPdCEs) involving the hydroquinone (HQ)/H2O2 system. The developed immune platform demonstrates LOD values of 6.88 pg mL−1 and 0.11 mIU mL−1 for E2 and FSH standards, respectively and usefulness for the determination in saliva samples collected from different volunteers, giving results in agreement with the conventional ELISA methodologies. [ABSTRACT FROM AUTHOR]

The simple and effective method for the novel synthesis of Pt‐based nanoparticle was presented with high efficiency. The sensitive catalyst for the simultaneous detection of catechol and hydroquinone was prepared by depositing ternary metal complex on fluorine‐doped tin‐oxide (FTO). The composition and morphology of nanomaterials were characterized by TEM, HRTEM, XRD, XPS, and EDS (energy dispersive spectroscopy). The size of the Pt‐based nanomaterial was about 5±1 nm. The electrochemical performance of the modified catalyst was studied by CV, DPV, and EIS. The modified PtNiCu@FTO catalyst possessed good electro‐oxidation activity for hydroquinone and catechol and used for simultaneous detection of catechol and hydroquinone at scan rate of 20 mV s−1 (vs. Ag/AgCl). Detection responses were found in the ranges of 5–2900 μM for hydroquinone and 5–3000 μM for catechol. The detection limits (LOD) for HQ and CC were observed as 0.35 and 0.29 μM, respectively. The sensitivity of HQ and CC were 1515.55 and 1485 μA mM−1 cm−2, respectively. The prepared nanomaterial were effectively applied for the determination of CC and HQ in real samples. [ABSTRACT FROM AUTHOR]

A simple and highly selective electrochemical sensor based on carbonized lotus stem (CLS) was developed for the simultaneous determination of hydroquinone (HQ), catechol (CC), and nitrite (NT) by using cyclic voltammetry (CV) and amperometry (AMP) methods. The CLS was characterized by the methods including field emission scanning electron microscopy (FE‐SEM), Raman spectrum, FT‐IR spectrum and X‐ray diffraction (XRD). Brunauer‐Emmett‐Teller (BET) method was used to evaluate the pore structure and surface area of CLS. The oxidation peaks for HQ (116.2 mV), CC (220.1 mV), and NT (818.9 mV) were well separated under optimized conditions, which improved their simultaneous determination. The CLS modified electrode showed a good linear range between 1.0×10 −6 to 7.0×10 −4 M for HQ, and the detection limit was calculated as 0.15 μM. For CC the linear relationship was 1.0×10 −6 to 3.0×10 −3 M with the detection limit of 0.11 μM. For NT the linear relationship was 5.0×10 −7 to 4.0×10 −3 M with the detection limit of 0.09 μM. The results indicated that the intrinsic structure of natural biomass can be expected to design porous carbon for electrochemical sensors. [ABSTRACT FROM AUTHOR]

A new electrochemical sensor based on Poly(Isoleucine) modified glassy carbon electrode decorated with platinum nanoparticles (Pt/Poly(Isoleucine)/GCE) was developed for sensitive individual and simultaneous determination of hydroquinone (HQ) and catechol (CC). Scanning electron microscopy (SEM), Electrochemical impedance spectroscopy (EIS), Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) were performed in order to characterize the Pt/Poly(Isoleucine)/GCE nanocomposite. For simultaneous determination of HQ and CC, Pt/Poly(Isoleucine)/GCE showed wide linear range between the 0.01–100.0 μM. The detection limits were 0.006 μM for HQ and 0.005 μM for CC. The Pt/Poly(Isoleucine)/GC electrode exhibited good sensitivity and reliability in the simultaneous electroanalysis of two isomers in PBS of pH 7.5. The modified electrode was used to detect the isomers in naturel samples. [ABSTRACT FROM AUTHOR]

In this work, the carbon paste electrode was modified with a composite of a metal‐organic framework, nitrogen‐doped graphite, and gold nanoparticles and used as an electrochemical sensor for dihydroxybenzene isomers. The morphology and characteristics of the modifiers were found by SEM and FT‐IR. Electrochemical techniques showed the specific surface of the electrode to be significantly enhanced. The outcome achieved shows that this novel sensor displays an excellent electro‐catalytic activity towards the oxidation of these isomers. The sensor was applied to the simultaneous determination of each three isomers using DPV with a linear response in the concentration range of 5–105 nM. [ABSTRACT FROM AUTHOR]

In this work, we present a simple and efficient method for preparation of widely dispersed PtNiCo nanocatalyst on FTO without the use of any heavy complex structure. The proposed nanocatalyst enhances the chemical interaction of PtNiCo/FTO and increases its catalytic activity, which was used for electrochemical sensing of catechol and hydroquinone. The surface morphology was characterized by TEM, HRTEM, and XRD. The size of the PtNiCo/FTO octahedrons nanocatalyst was about 0.35–4 nm. Gradual increase of concentration exhibited linearity in oxidation peak response up to 1100 μM with a low detection limit of 0.79 μM for HQ and 1.05 μM for CC. The sensitivity is 1035 μAmM−1 cm−2 for catechol and 1197 μAmM−1 cm−2 for hydroquinone. The prepared nanomaterial/sensor applied to real water samples with good reproducibility (98–99 %). [ABSTRACT FROM AUTHOR]

In the present study, we report a facile method for preparing a porous MWCNTs/ZIF‐67 nanocomposite with the help of a morphology‐maintained ZIF‐67 in situ growth on multi‐walled carbon nanotubes. Interesting, the MWCNTs/ZIF‐67 nanocomposite demonstrated excellent electrochemical activity for hydroquinone (HQ) and catechol (CC) attribute to the effective interconnections ZIF‐67 crystals and MWCNTs. The analytical curves for HQ and CC obtained by differential pulse voltammetry (DPV) were linear in the range from 0.5 to 100 μM. Benefitting from the excellent conductivity of MWCNTs as well as the high surface area and porosity of ZIF‐67, the advanced nanocomposite displayed good reproducibility, high selectivity and excellent stability, and was successfully employed to assay the content of dihydroxybenzene isomers in the lake water samples. [ABSTRACT FROM AUTHOR]

A simple, sensitive and reliable electrochemical sensor has been developed based on CuO nanostructures modified glassy carbon electrode for simultaneous determination of hydroquinone (HQ) and ascorbic acid (AA). The CuO nano material was synthesized by aqueous chemical growth method using different sources of OH. The characterization of nano material was performed by Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy and energy dispersive X‐ray spectroscopy. The glassy carbon electrode was modified by CuO nano material using drop cast method and studied by cyclic voltammetry. The CuO/GCE exhibited excellent electrocatalytic activity towards the oxidations of HQ and AA in borate buffer solution (pH 8.0) and the corresponding electrochemical signals have appeared as two well resolved oxidation peaks with significant peak potential differences of (0.21V vs. Ag/AgCl). Differential pulse voltammetry was used for simultaneous determination of HQ and AA using the CuO/GCE. At the optimum conditions, for simultaneous determination by synchronous change of the analyte concentrations, the linear response ranges were between 0.0003–0.355 mM for HQ and 0.0001–0.30 mM for AA respectively. Furthermore, CuO/GCE was successfully applied for the independent determination of AA in fruit juices as well as for the simultaneous determination of HQ and AA in cosmetic samples. [ABSTRACT FROM AUTHOR]

A novel self‐protection sensor was successfully constructed based on an interesting thermo‐sensitive triblock polymer PS‐PNIPAm‐PS. At low temperatures (<24 °C), the analyte was able to undergo the redox process at the modified electrode. However, the polymer shrunk and accumulated at high temperatures (>30 °C), which dramatically increased the electron transfer resistance (Rct) of the modified electrode and consequently blocked the occurrence of the redox reaction to protect the electrode from high temperatures and enhance its stability. Under optimized conditions, the proposed sensor showed a good detection range for hydroquinone (6×10−7 to 2.35×10−3 M) and a low LOD (490 nM). The sensor was also successfully applied for detecting hydroquinone in real samples. The present work may provide a novel method for electrode protection, high‐temperature alarm, high‐temperature protection of batteries and new sensors production. [ABSTRACT FROM AUTHOR]

Here, Pd nanoparticles and poly(taurine) film was prepared on the glassy carbon electrode surface (Pd/Poly(TAU)/GCE) by the rapid electrochemical technique. The proposed composite surface was characterized by scanning electron microscopy(SEM), X‐ray photoelectron spectroscopy(XPS) and electrochemical impedance spectroscopy(EIS). Enhanced electron transfer ability and higher electroactive surface area were achieved at Pd/Poly(TAU)/GCE as compared to the bare GCE and polymer film electrode. The new and highly stable Pd/Poly(TAU)/GCE was employed for the individual and simultaneous determination of hydroquinone and catechol which were environmentally toxic. Under the optimized conditions, HQ and CC were individually determined by using the differantial pulse voltammetry in the linear ranges of 0.008–100 μM and 0.001–100 μM with the detection limits of (LOD) 2.1 nM and 0.68 nM, respectively. In case of simultaneous determination, LODs were found as 10 nM and 0.88 nM for HQ and CC, respectively. The content of both analytes in the real sample analysis was evaluated in the river water and tap water successfully. [ABSTRACT FROM AUTHOR]

In this study, stable CotA laccase from Bacillus subtilis 168 was adsorbed on electrode modified with a thiol graphene‐gold nanoparticle (thGP‐AuNPs) nanocomposite film. The novel bacterial laccase biosensor was employed for quantitative detection of hydroquinone (HQ) and the electrochemical properties of this laccase biosensor were investigated. The results indicate that the immobilized CotA shows great oxidation activity towards HQ in the presence of oxygen and the biosensor shows linear electrocatalytic activity in the concentration range from 1.6 to 409.6 μM, with a detection limit of 0.3 μM. Further, the CotA modified electrode, when compared to fungal laccase‐modified biosensors, shows better alkaline stability (retaining approximately 80 % and 70 % of response current at pH 8 and 9, respectively) and reusability (retaining ∼87 % of response current after 100 days). The development of this new kind of laccase on a biosensor will offer a novel tool for substance detection applications in hostile environments, especially for industrial pollutants. [ABSTRACT FROM AUTHOR]

This paper describes the results obtained in the development of the first electrochemical immunosensor described to date for the detection of E‐cadherin (E‐cad) protein, a relevant biomarker of prognosis and metastasis in cancer, based on the use of magnetic microcarriers (MBs) and amperometric transduction at screen‐printed carbon electrodes (SPCEs). Thus, the determination of E‐cad protein involved the use of two specific antibodies against this protein (one of them labelled with HRP) in a sandwich configuration onto HOOC‐MBs. The magnetic bioconjugates were captured onto SPCEs and the amperometric transduction was performed using the H2O2/hydroquinone (HQ) system. Under optimal conditions, this bioplatform demonstrated a wide linear concentration range (0.50–25 ng mL−1) and a detection limit as low as 0.16 ng mL−1, well below the optimal cut‐off level for the E‐cad protein (defined as 10,000 ng mL−1 for soluble E‐cad levels in serum). The developed sensor also showed a good reproducibility among measurements with seven different sensors constructed in the same manner (RSD, 5.4 %), stability for more than 15 days and good specificity towards other proteins commonly found on biological samples. The applicability of this simple handling bioplatform for the direct determination of this protein in cell lysates with different metastatic potential and extracts from paraffined‐embedded human colorectal cancer tissues of different grade were also demonstrated. [ABSTRACT FROM AUTHOR]

The detection of some environmental pollutants remains still a great challenge and the current methods suffer from low sensitivity, reproducibility and require sophisticated instruments. Here, a simple, sensitive and pH‐responsive electrochemical sensor for the detection of hydroquinone (HQ) was developed based on a pH‐responsive block copolymer polystyrene‐b‐poly(acrylic acid) (PS‐b‐PAA) and graphene oxide (GO) composite film (PG) modified glassy carbon electrode (GCE). The electrochemical behaviors of HQ at the modified GCE (PG/GCE) electrode were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The peak current of the PG/GCE electrode toward HQ was significantly enhanced at pH 7.0 and greatly suppressed below pH 6.0, which are caused by swelling and shrinking of pH‐responsive block copolymer and the synergistic effect with GO. The PG/GCE exhibited a reversible "On/Off" switch for the HQ electrochemical behaviors between pH 4.0 and pH 7.0. When the pH of the medium is 7.0, the PG complex film on the PG/GCE is in the "On" state, the linear detection range of HQ is from 16 μM to 104 μM with a detection limit as low as 0.34 μM. Furthermore, the PG/GCE can also successfully detect the HQ concentration of the lake water sample with satisfactory recovery, indicating that the pH‐responsive block copolymer/GO‐functionalized sensor provided a powerful avenue for simple, sensitive and convenient detection of HQ, which can be translated into practical application. [ABSTRACT FROM AUTHOR]

In this work facile one step synthesis of magnesium ferrite (MgFe2O4) nanoparticles decorated on reduced graphene oxide (MgFe@RGO) using a microwave assisted hydrothermal procedure is reported. The synthesized material was characterized with help of several techniques and applied for the modification of glassy carbon electrode. Such prepared electrode was utilized for successive simultaneous detection of structurally similar compounds, 1,2‐ and 1,4‐dihydroxibenzenes (catechol (CC) and hydroquinone (HQ)), using differential pulse voltammetry technique. It was found that oxidation current increases linearly with the concentrations of both investigated compounds. Detection limits for both species are ≤0.31 μM. The best analytical response in the presence of both CC and HQ, taking into account peak shape and peak current, was obtained at pH 5.6 utilizing acetate buffer solution. The often‐presented species in the surface waters as well as gallic acid and caffeine do not interfere with determination of CC and HQ, while ascorbic acid shows high interference. The method is successfully applied for detection of catechol and hydroquinone in real samples analyses. [ABSTRACT FROM AUTHOR]

Abstract: The second order voltammetric technique of high resolution, Differential Alternative Pulses Voltammetry (DAPV), was applied for the simultaneous determination of hydroquinone (HQ) and catechol (CC) on bare spectroscopic graphite electrode. Well resolved anodic and cathodic peaks situated on both sides of the zero line were obtained, while the differential pulse voltammograms were overlapped. The linear concentration range for HQ and CC quantification by DAPV was extended up to 20 μmol L−1 for both the isomers. The sensitivity of the determination was found to be 6.00 μA L μmol−1 and 3.61 μA L μmol−1, while the limit of detection reached was 0.2 μmol L−1 and 0.5 μmol L−1 for HQ and CC, respectively. No interference was observed from the commonly coexisting organic species such as resorcinol, phenol and p‐benzoquinone. The great resolution power of DAPV permitted obtaining excellent results without any electrode modification and any mathematical data processing. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a rapid and sensitive modified electrode for the simultaneous determination of hydroquinone (HQ) and bisphenol A (BPA) is proposed. The simultaneous determination of these two compounds is extremely important since they can coexist in the same sample and are very harmful to plants, animals and the environment in general. A carbon paste electrode (CPE) was modified with silver nanoparticles (nAg) and polyvinylpyrrolidone (PVP). The PVP was used as a reducing and stabilizing agent of nAg from silver nitrate in aqueous media. The nAg‐PVP composite obtained was characterized by transmission electron microscopy and UV‐vis spectroscopy. The electrochemical behavior of HQ and BPA at the nAg‐PVP/CPE was investigated in 0.1 mol L−1 B−R buffer (pH 6.0) using cyclic voltammetry (CV) and square wave voltammetry (SWV). The results indicate that the electrochemical responses are improved significantly with the use of the modified electrode. The calibration curves obtained by SWV, under the optimized conditions, showed linear ranges of 0.09–2.00 μmol L−1 for HQ (limit of detection 0.088 μmol L−1) and 0.04–1.00 μmol L−1 for BPA (limit of detection 0.025 μmol L−1). The modified electrode was successfully applied in the analysis of water samples and the results were comparable to those obtained using UV‐vis spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: A stable complex of silver nanoparticles (Ag NPs) capped by cysteamine (Cst) together with single‐walled carbon nanotube (CNTs) was used to modify a glassy carbon electrode (GCE) for simultaneous detection of hydroquinone (HQ) and catechol (CT). The resulting electrode (AgCst‐CNTs/GCE) showed excellent electrocatalysis and reversibility towards this electroactive pair. The peak separations of their oxidation‐reduction peaks decreased significantly, compared with those of the unmodified GCE. The signal responses of the AgCst‐CNTs/GCE were 5‐fold higher while its peak potential separation remained unchanged (ca. 130 mV), compared to the CNTs‐modified GCE. The oxidation peak currents obtained for HQ and CT exhibited linearly from submicromolar to hundred micromolar concentrations without any cross‐interference. The modified electrode possessed a very large active surface area with a detection limit (S/N=3) of 10 and 40 nM for HQ and CT, respectively. The sensor was demonstrated for the analysis of river water and topical cream as evinced by high accuracy and reproducibility. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports a novel analytical device for the determination of 2‐(1,1‐dimethylethyl)‐1,4‐benzenediol antioxidant (TBHQ) in cosmetic samples exploiting a photoelectrochemical sensor based on titanium dioxide nanoparticles sensitized with lithium 7,7′,8,8′‐tetracyanoquinodimethanide on indium tin oxide electrode. The proposed photoelectrochemical sensor possesses the capacity of harvesting light energy from a commercial light‐emitting diode (LED) lamp for the determination of TBHQ molecules. The photoelectrochemical sensor presented photocurrent response to antioxidant about 2‐fold higher than pure titanium dioxide. The sensor shows high photocurrent response to TBHQ antioxidant in comparison to photocurrent response to 2,3‐t‐butyl‐4‐hydroxyanisole and 2,6‐Di‐tert‐butyl‐4‐methylphenol, indicating selectivity to TBHQ. Under optimized experimental conditions, the photoelectrochemical sensor presents two linear ranges of response for the analyte, the former from 0.6 to 200 μmol L−1, and the latter from 200 to 5000 μmol L−1. A low limit of detection of 0.17 μmol L−1 was obtained for the proposed photoelectrochemical sensor. The sensor was successfully employed to the analysis of cosmetic samples, with recovery values between 96 % and 98 %. [ABSTRACT FROM AUTHOR]

Surface active ionic liquid (SAIL) micelle assisted, simultaneous and highly sensitive electrochemical sensing of dopamine (DA) and ascorbic acid (AA) is presented. Results presented herein establish that SAILs viz.1-dodecyl-3-methyl imidazolium chloride ([DDMIM][Cl]), 1-octyl-3-methyl imidazolium chloride ([OMIM][Cl]) and 1-butyl-3-methyl imidazolium chloride ([BMIM][Cl]) exhibit a probe and SAIL nature/concentration specific impact on the redox behaviour of hydroquinone (H2Q), dopamine (DA) and ascorbic acid (AA). To our observations, the electrochemical behaviour of DA and AA is affected oppositely by SAILs with the apparent effects being more appreciable in presence of [DDMIM][Cl]. In the presence of [DDMIM][Cl] micelles, the electro-oxidation of AA was observed to occur at potentials about 350 mV less positive than required for electrooxidation of DA, an important advantage that minimises the interference of former in sensing of the later. The peak to peak potential separation of 350 mV observed in presence of [DDMIM][Cl] micelles is the largest to be reported so far. The DPV signal for DA and AA displayed a linear response in the concentration range of 6.6 to 99.9 μM and 6.6 to 131.5 μM respectively. Very low detection limits of 0.0161 μM for DA in presence of 39.8 μM AA and 0.0227 μM for AA in presence of 39.8 μM DA were estimated in micellar phase of [DDMIM][Cl]. [ABSTRACT FROM AUTHOR]

Two shapes of TiO2 nanomaterial will largely affect the catalytic activity. TiO2 nanoparticles (NPs) and TiO2 nanofibers (NFs) were used to investigate the effect of shape on catalytic activities and get the optimum shape of catalysis. Electrochemical behaviors of two modified electrodes by TiO2 nanomaterial were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. Various electrochemical parameters such as electrode surface area and electron-transfer rate constant were also studied and calculated in the aqueous solution. Results showed that the response of NF is better than NP for electrooxidation of hydroquinone (HQ). The different electrochemical response of TiO2 is related to the various morphological structures, so controlling the shape and structure of nanomaterial is very important factor which is because of the powerful correlation between these parameters and their optical, catalytic and electrical properties. [ABSTRACT FROM AUTHOR]

Fast-scan differential pulse voltammetry (FSDPV) is an electroanalytical technique that uses high scan rate to record voltammograms within several milliseconds and ensures high temporal resolution. Here, a FSDPV on a glassy carbon working electrode in combination with a flow injection analysis (FIA) system was developed and characterized using the hydroquinone/quinone redox system. Later, enhanced resolution of the technique was confirmed with the parallel determination of caffeic acid and p-coumaric acid. Finally, the optimized procedure has been applied for the first time to determine capsacinoids in chili pepper and total phenols in extra virgin olive oils. The proposed procedure is fast, simple, and enables the monitoring of complex samples in real-time. [ABSTRACT FROM AUTHOR]

Graphene nanosheets were facilely prepared through one-step liquid-phase exfoliation of graphite powder in N, N-dimethylformamide (DMF) with the assistance of sodium citrate, and then employed to modify the surface of glassy carbon electrode (GCE) via solvent evaporation. Subsequently, mercaptoacetic acid (MA) was electrodeposited onto the surface of exfoliated graphene-modified GCE (EG/GCE) to construct a composite film-modified electrode ( pMA/EG/GCE). The electrochemical behaviors of hydroquinone (HQ) and catechol (CC) were studied. It was found that the oxidation peak currents of HQ and CC increased obviously on the surface of EG/GCE and pMA/GCE, compared with those on bare GCE. However, the oxidation signals of HQ and CC further enhanced greatly on the surface of pMA/EG/GCE, showing strong synergetic enhancement effects. As a result, a highly sensitive electrochemical method was developed for the simultaneous determination of HQ and CC. The linear range was from 0.1 to 100 μmol L−1, and the detection limits were 85 and 80 nmol L−1 for HQ and CC (S/N=3). [ABSTRACT FROM AUTHOR]

Carboxyl functionalized graphene (CFG) self-assembled monolayers (SAMs) were constructed on the carboxylated glassy carbon electrode based on covalent interaction for simultaneous determination of hydroquinone (HQ) and catechol (CC). Scanning electron microscopy and electrochemical impedance spectroscopy results proved that the CFG SAMs was successfully formed with enhanced conductivity. According to electrochemical voltammetry experiments, the modified electrode showed excellent sensitivity and selectivity for HQ and CC. Under optimal conditions, the sensing platform showed wide linear response for HQ and CC with detection limit of 0.2 µM ( S/N=3) and 0.6 µM ( S/N=3), respectively. Moreover, the sensor also displays good reproducibility and stability. [ABSTRACT FROM AUTHOR]

In the present study, we report the simultaneous electrochemical determination of hydroquinone (HQ), catechol (CC) and resorcinol (RC) at gold nanoparticles (Au-NPs) decorated reduced graphene oxide (RGO) modified electrode. An enhanced and well defined peak current response with a better peak separation of HQ, CC and RC is observed at RGO/Au-NPs composite than that of RGO and Au-NPs modified electrodes. The fabricated modified electrode shows a wide linear response in the concentration range of 3-90 µM, 3-300 µM and 15-150 µM for HQ, CC and RC, respectively. The detection limit of HQ, CC and RC is found as 0.15 mM, 0.12 mM and 0.78 mM, respectively. [ABSTRACT FROM AUTHOR]

In this work, we present a simple homemade batch-injection analysis cell for screen-printed electrodes (BIA-SPE). The potential of the proposed system for on-site analysis was demonstrated by the determination of carbendazim, catechol, and hydroquinone in tap water. The system provided reduced injection volume (30 µL), high analytical frequency (≈200 h−1) and low detection limits (nanomolar level). Moreover, the BIA-SPE cell presented better stability ( RSD≈0.4 %) than a conventional flow injection cell for SPE ( RSD≈5.0 %) in organic media. The proposed homemade BIA-SPE cell is very simple, inexpensive and can be easily constructed in any laboratory. [ABSTRACT FROM AUTHOR]

A simple method for electrochemical oxidation and degradation of carcinogenic tetracene (TC) to surface confined redox active quinone species (TCO) on a pristine-multiwalled carbon nanotube modified (MWCNT) gold electrode surface (Au/MWCNT) by applying a static potential at 0.9 V vs. Ag/AgCl in pH 7 phosphate buffer solution has been demonstrated. Various physicochemical characterizations of MWCNT@TCO by TEM, FT-IR, Raman spectroscopy and GC-MS reveal the presence of two types of redox sites, hydroquinone and anthraquinone derivatives within the MWCNT@TCO. The modified electrode showed selective electrocatalytic reduction and amperometric i- t sensing of H2O2 with a detection limit (signal-to-noise=3) of 122 nM. [ABSTRACT FROM AUTHOR]

Nanocrystalline zeolites of different framework structures were prepared by the addition of suitable structure directing agents in the synthesis composition of conventional zeolites. Zeolite modified carbon paste electrodes were constructed for the simultaneous determination of dihydroxybenzene isomers. Nanocrystalline zeolite Beta modified carbon paste electrode exhibited the highest electrocatalytic activity. Under optimum conditions, wide linear range was obtained from 150 nM to 400 µM with lower detection limit of 100, 130, and 100 nM for hydroquinone, catechol, and resorcinol, respectively. The analytical performance of the proposed sensor was demonstrated in the simultaneous determination of dihydroxybenzene isomers in different environmental water samples. [ABSTRACT FROM AUTHOR]

Electrolytic efficiency of battery-operated flow-through thin-layer electrochemical (EC; echem) cell used in EC/ESI-MS was investigated. Two stainless steel capillaries joined by PTFE tubing formed the thin-layer EC cell. Echem reaction efficiency of ferrocyanide, dopamine and hydroquinone oxidation in the EC cell was low and decreased with increasing MeOH volume fraction in the MeOH/H2O carrier solutions with low conductivity. Water oxidation dominated the cell current and migration of ferrocyanide was observed. Flow rate of 50-200 µL/h had a very small effect on EC cell current. Dopamine oxidation current in the EC cell and dopamine ion intensity in EC/ESI-MS showed a direct correlation. [ABSTRACT FROM AUTHOR]

A novel sensor for sensitive determination of hydroquinone (HQ) and catechol (CC) was proposed using a Fe3O4 microspheres-graphene oxide (Fe3O4-GO) composites modified glassy carbon electrode (GCE) which was further encapsulated with chitosan (Chit-Fe3O4-GO/GCE). The excellent electrocatalytic performance is probably related to the strong synergistic effect of the composites. The proposed sensor shows a linear response for HQ and CC in wide concentration ranges from 1.5 to 150 µM and 1 to 410 µM, with detection limits ( S/ N=3) of 20 and 250 nM, respectively. Additionally, the sensor exhibits good selectivity and stability in tap water samples. [ABSTRACT FROM AUTHOR]

Much research-to-date exists to create sensitive and selective DNA sensors. A variety of approaches are adopted, including those involving polypyrrole and electrical impedance spectroscopy. Combined these are able to sense as well as aptly transduce signals. Many such sensors employ ferri/ferrocyanide to exhibit surface hybridization. This redox reporter, though with merits, can prove disadvantageous. To this end, a comparative study was performed with the redox reporter hydroquinone. For comparison purposes ferri/ferrocyanide indicated greater sensitivity, suggested to arise from inherent charge. Conversely, with hydroquinone steric hindrance is the main influencing factor. Such a study aims to guide design of analogous sensors. [ABSTRACT FROM AUTHOR]

Lotus stem, Carbonization, Hydroquinone, Catechol, Nitrite, Simultaneous determination Keywords: Lotus stem; Carbonization; Hydroquinone; Catechol; Nitrite; Simultaneous determination EN Lotus stem Carbonization Hydroquinone Catechol Nitrite Simultaneous determination 1 1 1 04/12/21 20210401 NES 210401 The cover image is based on the Full Paper I Electrochemical Sensing Platform Based on Lotus Stem-derived Porous Carbon for the Simultaneous Determination of Hydroquinone, Catechol and Nitrite i by Zhenyong Lu et al., DOI: 10.1002/elan.202060478. Cover Feature: Electrochemical Sensing Platform Based on Lotus Stem-derived Porous Carbon for the Simultaneous Determination of Hydroquinone, Catechol and Nitrite (Electroanalysis 4/2021). [Extracted from the article]