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This study developed an electrochemical sensor for the determination of Mn2+in Chinese liquor by modifying a glass carbon electrode with TiO2-NH2@COFDPTB, which was synthesized viathe controllable growth of COFDPTBonto the surface of TiO2-NH2using the Schiff-base condensation reaction between 2,5-dimethoxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)benzene. The morphological and structural characterization studies of the proposed TiO2-NH2@COFDPTBwere carried out by SEM, TEM, HRTEM, EDX, BET, XRD and FTIR techniques. Owing to the excellent properties and the synergism between TiO2and COFDPTB, the introduction of TiO2-NH2@COFDPTBimproved the electrochemical response significantly. By optimizing the experimental parameters, the sensor exhibited good linearity in the range of 0.1–1.0 nM and 0.08–10 μM with a detection limit of 2.83 × 10−11M and 9.50 × 10−9M, respectively, showing competitive performance for Mn2+determination. Besides, the proposed sensor was successfully applied to Mn2+detection in liquor samples, suggesting its practical application performance.

In this work, a kind of molecularly imprinted polymer (MIP) was prepared by using metronidazole (MNZ) as the template, pyrrole as the functional monomer and vertically cross-linked two-dimensional Sn3O4(2D Sn3O4) nanoplates as the support. The developed MIP/2D Sn3O4was characterized by SEM, XRD, XPS and FT-IR. It was used to modify a glassy carbon electrode (GCE) to construct a novel MNZ electrochemical sensor. Parameters affecting the performance of the sensor were thoroughly investigated and optimized. The results revealed that 2D Sn3O4is promising as a support for MNZ imprinting. Owing to the 2D structure, large active surface, functionalization and high electrical conductivity, the MIP/2D Sn3O4modified electrode showed a wide linear range and low detection limit. The differential pulse voltammetric peak currents produced on the MIP/2D Sn3O4electrochemical sensor showed a linear relationship for concentrations of MNZ in the range of 0.025–2.5 μM. The detection limit of this sensor was down to 0.0032 μM (S/N = 3). This MIP/2D Sn3O4sensor was successfully used to detect MNZ in honeybee samples without any separation or accumulation processes, demonstrating that MIP/2D Sn3O4is a promising biomimetic material for use in electroanalysis and other relevant fields.

A rapid and sensitive approach for the determination of trace levels of cadmium using stripping voltammetry coupled with a sequential injection lab-on-valve system was developed. The proposed method was based on the accumulation of cadmium on the multi-walled carbon nanotubes/Fe3O4nanoparticles modified electrode where iodide was used as the induced adsorption media. Different parameters such as supporting electrolyte and its pH, concentration of KI, amounts of modifier, accumulation potential, accumulation time, and flow rate were investigated to enhance the analytical performance. Under the optimum conditions, the signal intensity shows a linear relationship with the concentration of cadmium over the range of 5 × 10−9to 2 × 10−7mol L−1. A sampling frequency of 24 per hour and a detection limit of 2.7 × 10−9mol L−1were obtained with an accumulation time of 120 s. The relative standard deviation for 11 repeated measurements of 1 × 10−8mol L−1cadmium was 3.2%. The analytical use of the established method was validated by applying it to the determination of cadmium in natural waters samples and certified reference materials.

In this study, a method for the determination of alkylamine carbonate (AAC) nonionic–anion oil displacement agent in oil-field water was developed for the first time, involving pre-column derivatization using a novel labeling agent and HPLC with diode-array detection. The derivatization and chromatographic separation conditions were investigated thoroughly. The analyte was labeled with 4-methoxybenzenesulfonyl fluoride at 50 °C for 20 min. When the method was applied in the determination of C18A5C (an AAC oil displacement agent containing eighteen alkyl and five amino groups) a linear calibration curve was obtained from 1.0 to 100.0 μg mL−1with a correlation coefficient of more than 0.999 and a detection limit of 0.05 μg mL−1. In the determination of real oil-field water samples, the recovery range of C18A5C was 91.8% to 96.2%, and the intra-day and inter-day relative standard deviations were 2.9–3.5% and 3.8–4.3%, respectively. The experimental results demonstrate that this method, with its merits of simplicity in pretreatment, rapidity in derivatization, and stability of the derivatives, can be employed in the analysis of C18A5C and has potential application in the detection of other oil displacement surfactants containing amino groups. It is of great significance to develop a fast, easy-to-operate, sensitive and reliable method for environmental impact assessment.