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Phenolic compounds contain classes of flavonoids and non-flavonoids, which occur naturally as secondary metabolites in plants. These compounds, when consumed in food substances, improve human health because of their antioxidant properties against oxidative damage diseases. In this study, an electrochemical sensor was developed using a carbon paste electrode (CPE) modified with Fe3O4 nanoparticles (MCPE) for the electrosensitive determination of sinapic acid, syringic acid, and rutin. The characterization techniques adapted for CPE, MCPE electrodes, and the solution interface were cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Scan rate and pH were the parameters subjected to optimization studies for the determination of phenolic compounds. The incorporation of Fe3O4 nanoparticles to the CPE as a sensor showed excellent sensitivity, selectivity, repeatability, reproducibility, stability, and low preparation cost. The limits of detection (LOD) obtained were 2.2 × 10−7 M for sinapic acid, 2.6 × 10−7 M for syringic acid, and 0.8 × 10−7 M for rutin, respectively. The fabricated electrochemical sensor was applied to determine phenolic compounds in real samples of red and white wine.

A dopamine-imprinted monolithic column was prepared and used in capillary electrochromatography as stationary phase for the first time. Dopamine was selectively separated from aqueous solution containing the competitor molecule norepinephrine, which is similar in size and shape to the template molecule. Morphology of the dopamine-imprinted column was observed by scanning electron microscopy. The influence of the organic solvent content of mobile phase, applied pressure and pH of the mobile phase on the recognition of dopamine by the imprinted monolithic column has been evaluated, and the imprinting effect in the dopamine-imprinted monolithic polymer was verified. Developed dopamine-imprinted monolithic column resulted in excellent separation of dopamine from structurally related competitor molecule, norepinephrine. Separation was achieved in a short period of 10 min, with the electrophoretic mobility of 5.81 × 10 m V s at pH 5.0 and 500 mbar pressure.

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Trietazine was selectively separated from aqueous solution containing the competitor molecule cyanazine, which is similar in size and shape to the template molecule. Structural features of the molecularly imprinted column were figured out by SEM. The influence of the mobile-phase composition, applied electrical field, and pH of the mobile phase on the recognition of trietazine by the imprinted monolithic polymer has been evaluated, and the imprint effect in the trietazine-imprinted monolithic polymer was demonstrated by an imprinting factor. The optimized monolithic column resulted in separation of trietazine from a structurally related competitor molecule, cyanazine. In addition, fast separation was obtained within 6 min by applying higher electrical field, with the electrophoretic mobility of 2.97 × 10(-8) m(2) V(-1) s(-1) at pH 11.0.

Water contamination by heavy metal pollution is induced by rapid industrialization and urbanization. Removal of heavy metal ions from wastewater is of prime importance for a clean environment and human health. The heavy metal problem is seriously threatened to human health. In addition, these metals are toxic and carcinogenic. They cause serious problems for aquatic ecosystems and especially humans. Different methods have been utilized to remove heavy metals from the wastewater, such as membrane filtration, adsorption, and ion exchange. Adsorption is one of the most efficient processes to clean contaminated water. The adsorption process presents advantages such as availability, low cost, and eco-friendly nature. The commercial adsorbents and the polymeric adsorbents are showed a high removal capacity for heavy metal ions capturing and removing from wastewater. Several researchers have widely used cryogels as a unique bio-adsorbent for heavy metals removal from wastewaters. Cryogels are efficient for the removal of heavy metal ions. This manuscript comprehensively and critically reviews current research in heavy metal adsorption by cryogels that prepared various technology and highlights the main advantages of these materials. Cryogels are synthetic polymers used in adsorption experiments in recent years. Because of their macropores, they provide an excellent advantage as an adsorbent in continuous and batch adsorption processes. The process applied for cryogel formation is called cryogelation. These macroporous gel matrices can be produced with different shapes and the gels are of interest in the bioseparation area since they can meet needs that conventional chromatographic media are less suitable to fulfill. The structure, synthesis, and composition of various cryogels are presented. Cryogels are generally synthesized by bulk polymerization under semifrozen conditions at −12 and 18°C for 12 to 24 h. The cryogels have a high removal capacity rate of over 90%. In the cryogels based studies, Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal, surface area, elemental, and computerized microtomography (μCT) analyses can be used for the characterization of cryogels structure.

In this study, selective and sensitive detection of neurotransmitter dopamine (DA) from both aqueous solution and serum samples was performed by surface plasmon resonance (SPR) sensor based on molecular imprinting...

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