•A new simple and ultrasensitive sensing platform by using β-cyclodextrin polymer/rGO/polypyrrole modified pyrolytic graphite electrode (β-CDP/rGO/PPy/PGE) was constructed.•The proposed electrochemical sensor exhibited high sensitivity for the determination polychlorinated biphenyls (PCBs) which have no electrochemical activity.•The newly developed method was successfully applied to quantitative determination of PCBs level in sediment core collected from Lake Nansihu.A new electrochemical sensor for ultrasensitive determination the polychlorinated biphenyls (PCBs) is presented here, exploiting the electrochemical route of sensing which has a distinct advantage over other conventional analysis. Chemically converted reduced graphene oxide modified with β-cyclodextrin polymer (β-CDP), being more soluble in water and the formation constants of target molecules with β-CDP are generally stronger and larger than that of β-CD, provides a platform for the electrochemical detection of PCBs using ferrocene as redox indicator. Ferrocene can form a host-guest complex with β-CDP. PCBs will replace the ferrocene in the cavity due to its higher affinity towards β-CDP, offering wide linear range and higher detection sensitivity via selective host-guest interaction. As ferrocene is a well known redox probe and hence can be easily detected using differential pulse voltammetery (DPV) technique. The new method exhibited excellent analytical performance toward PCBs with a low detection limit of 5.0 × 10−13 M (S/N = 3). More importantly, the developed method was applied to the quantitative determination of PCBs level in sediment core collected from Lake Nansihu and displayed satisfactory results. These results indicate that the method offers considerable potential for trace PCBs monitoring. We believe that the method has a profound impact on the design of a convenient platform for rapid screening and determination of PCBs in environment.

A simple, signal-off electrochemiluminescence (ECL) immunosensor for sensitive and selective detection of alpha fetoprotein (AFP) was developed based on gold nanoparticle (AuNPs) modified graphite-like carbon nitride nanosheet (g-C3N4 NSs) nanohybrids (Au-g-C3N4 NHs). Compared to the g-C3N4 NS modified glassy carbon electrode (GCE), the ECL intensity is more obvious at the Au-g-C3N4 NH modified GCE due to the fact that AuNPs can promote electron transfer and electrocatalytic reduction of S2O82− to produce large amounts of hole donor (SO4˙−). Results demonstrated that the ECL signal of the g-C3N4 NSs decreased due to the interaction between antibody and antigen on the modified electrode. Thus, an ECL immunosensor for the detection of AFP was realized by monitoring the ECL intensity change of g-C3N4 NSs. The factors influencing the performance of the immunosensor were investigated in detail. Under optimal conditions, the proposed biosensor achieved a wide line from 0.001 to 5.0 ng mL−1 with a detection limit of 0.0005 ng mL−1. Furthermore, the ECL immunosensor was successfully applied to the determination of AFP in serum samples, providing a promising effective strategy for AFP detection.

•A novel electrochemical sensing platform by self-assembling of HS-β-cyclodextrin/gold nanoparticles onto indium tin oxide electrode (HS-β-CD/AuNPs/SAM/ITO electrode) surface was constructed.•The proposed electrochemical sensor exhibited high sensitivity for the determination 2,4,6-trichlorophenol which electrochemical activity is very weak.•The newly developed method was successfully applied to quantitatively determine 2,4,6-trichlorophenol in tap water samples.A new electrochemical sensor for determination of 2,4,6-trichlorophenol (2,4,6-TCP) was fabricated. The characterization of the sensor was studied by scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry techniques. The electrochemical behavior of 2,4,6-TCP was investigated using cyclic voltammetry and differential pulse voltammetry at the HS-β-cyclodextrin (HS-β-CD)/gold nanoparticles (AuNPs) composite modified indium tin oxide (ITO) electrode. The results showed that the current responses of 2,4,6-TCP greatly enhanced due to the high catalytic activity and enrichment capability of composites. The peak current of 2,4,6-TCP increases linearly with the increase of the 2,4,6-TCP concentration from 3.0 × 10−9 to 2.8 × 10−8 M, with the limit of detection of 1.0 × 10−9. Further more, the modified electrode was successfully applied to detect the level of 2,4,6-TCP in tap water samples with excellent sensitivity.

In this paper, specific electrochemical interaction between phenanthrene (Phe) and anthraquinone sulfonate (AQS) was first investigated by Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). Poly diallyldimethylammonium chloride (PDDA) and AQS were modified onto indium–tin oxide (AQS/PDDA/ITO) by self-assembling. Owing to the specific interaction between AQS and Phe, the amount of Phe could be quantified by the electrochemical oxidation peak current difference of AQS at AQS/PDDA/ITO in the range from 1.0 × 10−12 to 1.0 × 10−9 mol L−1 with a linearity (r = 0.9942) and a low detection limit of 5.0 × 10−13 mol L−1 (S/N = 3). As an example of its practical application, the new sensor was used for quantitative determination of Phe in a standard sample and cloud-rain water samples of Mount Taishan with satisfactory results.

The amino-functionalized, SBA-15-modified carbon paste electrode (NH2-SBA15/CPE) was prepared and successfully developed for the sensitive and simultaneous electrochemical determination of naphthol isomers. The electrochemical behaviors of 1-naphthol (1-NAP) and 2-naphthol (2-NAP) on different electrodes were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in Britton–Robinson buffer solutions (pH 2.5). The results demonstrated that the NH2-SBA15/CPE exhibited better electrocatalytic performance and higher sensitivity toward naphthol isomers than those at the SBA15/CPE and bare CPE, and it could well separate their oxidation peaks by CV and DPV. Under the optimized conditions, the oxidation peak currents showed good linearity in the ranges of 1.0 × 10−8–1.0 × 10−6 M for 1-NAP and 2-NAP, with a low detection limit of 1.0 × 10−9 M (S/N = 3). More importantly, the developed method was applied to the quantitative determination of 1-NAP and 2-NAP in wastewater samples from a chemical plant and displayed satisfactory sensitivity and selectivity.

We are just beginning to exploit the fascinating potential of thionine, called electrochemical probe that can selectively recognize specific polycyclic aromatic hydrocarbons (PAHs), as tools for the detection of tricyclic aromatic hydrocarbons phenanthrene (PHE) and anthracene (ANT). A novel electrochemical sensing platform by modification of electroactive thionine functionalized graphene onto glass carbon electrode (Th/GRs/GCE) surface was constructed. The immobilized thionine showed a remarkable stability, which may benefit from the π–π stacking force with graphene. Under optimum conditions, the proposed electrochemical sensor exhibited high sensitivity and low detection limit for detecting PHE and ANT. The total amount of PHE and ANT could be quantified in a wide range of 10 pM–0.1 μM with a good linearity (R2 = 0.9979) and a low detection limit of 0.1 pM (S/N = 3). Compounds which possess one or two benzene rings or PAHs with more than three rings, such as benzene, naphthalene (NAP), benzo[a]pyrene (BaP) and pyrene (PYR) show little interference on the detection. Consequently, a simple and sensitive electrochemical method was proposed for the determination of PHE and ANT, which was used to determine PHE and ANT in waste water samples. The electrochemical method provides a general tool that complements the commonly used spectroscopic methods and immune method for the detection of PAHs.

The simultaneous voltammetric determination of dihydroxybenzene isomers was investigated using cyclic and differential pulse voltammetries at the amino-functionalized SBA-15 mesoporous silica-modified carbon paste electrode (NH2-SBA15/CPE) in phosphate buffer solution (pH 6.0). The NH2-SBA15/CPE showed a larger peak current and higher selectivity for the dihydroxybenzene isomers in comparison with the bare carbon paste electrode (CPE) and SBA-15 mesoporous silica-modified carbon paste electrode (SBA15/CPE). The oxidation peak potential difference between hydroquinone (HQ) and catechol (CC) was 115 mV and was 396 mV between catechol and resorcinol (RC). This indicated that catechol, resorcinol and hydroquinone could be identified entirely at the NH2-SBA15/CPE. Under the optimized conditions, the amperometric currents were linear over ranges from the following: 0.8–160 μmol L−1 for hydroquinone, 1.0–140 μmol L−1 for catechol and 2.0–160 μmol L−1 for resorcinol. The detection limits were 0.3, 0.5 and 0.8 μmol L−1, respectively. The proposed electrode can be applied to the simultaneous determination of dihydroxybenzene isomers in mixtures without previous chemical or physical separations.

The β-cyclodextrin functionalized SBA-15 was synthesized and employed for the fabrication of modified carbon paste electrodes. The electrochemical behavior of o-nitrophenol (o-NP), m-nitrophenol (m-NP) and p-nitrophenol (p-NP) was investigated at the modified electrode. Due to the inhibition of bonded cyclodextrin, the electrode reaction of nitrophenol was interrupted at hydroxylaminophenol stage, three nitrophenol isomers can be discriminated simultaneously according to the different potential of nitrosophenol/hydroxylaminophenol redox reaction. Therefore, low detection limits of 1.0 × 10−8 mol L−1 for o-NP and p-NP, 5.0 × 10−8 mol L−1 for m-NP were obtained, the linear ranges of the calibration curves are 2.0 × 10−7 to 1.4 × 10−6 mol L−1, 2.0 × 10−7 to 1.6 × 10−6 mol L−1 and 2.0 × 10−7 to 1.4 × 10−6 mol L−1, respectively. Consequently, a selective nitrophenol isomers electrochemical sensor was successfully fabricated and a sensitive method was developed for the determination of o-NP, m-NP and p-NP in aqueous solution simultaneously.Highlights► CD-SBA/CPE exhibits significantly adsorptive capability towards nitrophenol isomers. ► The nitrophenol isomers can be discriminated simultaneously according to the different potential of nitrosophenol/hydroxylaminophenol redox reaction. ► A sensitive method was developed for determination of o-NP, m-NP and p-NP simultaneously, with detection limits of 1.0 × 10−8 mol L−1, 5.0 × 10−8 mol L−1 and 1.0 × 10−8 mol L−1, respectively.

The electrochemical behaviors of magnolol have been studied at glassy carbon electrode using cyclic voltammetry, linear sweep voltammetry and chronocoulometry. Moreover, its interaction with DNA was investigated in solution by electrochemical methods and ultraviolet–visible spectroscopy. The experiment results indicated that the electrochemical oxidation of magnolol was an irreversible process with one proton and one electron transfer. The electron transfer coefficient (α) was calculated to be 0.441 ± 0.001. At the scan rate from 100 mV/s to 450 mV/s, the electrode process was controlled by the adsorption step and at the range of 600–950 mV/s the electrochemical oxidation was diffusion controlled process. The corresponding electrochemical rate constant (ks) was 0.0760 ± 0.0001 s−1. Through chronocoulometry experiment, the diffusion coefficient (D) and the surface concentration (Γ) were obtained as (3.76 ± 0.01) × 10−7 cm2/s and (2.98 ± 0.01) × 10−10 mol/cm2. In addition, the interaction of magnolol and DNA was ascribed to be electrostatic interaction and the calculated association constant (β) and Hill coefficient (m) were 1.14 × 105 M−1 and 0.973. At last a sensitive and convenient electrochemical method was proposed for the determination of magnolol.

A modified graphite electrode with functionalized ionic liquid (IL) pyridinium derivative of β-cyclodextrin ([CDbPy]BF4) was prepared by layer-by-layer self-assembly technique. With ferrocene as probe, the characterization of the (CDIL/PDDA)n/GE SAMs in the solution of phosphate (PBS, pH 7.0) was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry. The electrochemical behavior of p-chloronitrobenzene (p-CNB) at the modified electrode was studied. It was found that the modified electrode could catalyze the reduction of p-CNB and made the cathode peak move about 100 mV in positive direction in the solution of 0.1 mol/L PBS (pH 7.0). Differential pulse voltammetry (DPV) was applied to the determination of p-CNB in waste water with satisfactory results. The detection limit and the linear range of the concentration of p-CNB to the reduction peak current were 8.0 × 10−8 mol/L and 3.0 × 10−7–1.0 × 10−5 mol/L, respectively.