A novel ratiometric electrochemical sensing platform combined with molecularly imprinted polymer and Fe-MOF-NH/CNTs-NH/MXene composite for efficient detection of ofloxacin.

Background: Ofloxacin (OFL) is often abused in medicine and animal husbandry, which poses a great threat to human health and ecological environment. Therefore, it is necessary to establish efficient method to detect OFL. Electrochemical sensor has attracted widespread attention due to the advantages of low cost and fast response.

A molecularly imprinted polymer monolithic column with dual template and bifunctional monomers for selective extraction and simultaneous determination of eight phenolics from polycarbonate cups.

A molecularly imprinted polymer (MIP) monolithic column was prepared in situ in a pipette tip using phenol and bisphenol A as dual templates, 4-vinyl pyridine and β-cyclodextrin as bifunctional monomers. It was used for the selective and simultaneous solid phase extraction of eight phenolics, including phenol, m-cresol, p-tert-butylphenol, bisphenol A, bisphenol B, bisphenol E, bisphenol Z, and bisphenol AP. The MIP monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and nitrogen adsorption experiment.

A Zn-based metal coordination cluster Zn used for solid phase microextraction of ten phenolic compounds from water and soil.

Exploring coating materials with superior extraction efficiency has always been the pursuit in the field of solid phase microextraction (SPME). Metal coordination clusters with high thermal and chemical stability, abundant functional groups as active adsorption site are the promising coatings. In the study, a Zn(HL)(NO) (Zn, HL =(1,2-bis-(benzo[d]imidazol-2-yl)-ethenol) cluster coating was prepared and applied for SPME of ten phenols.

Fabrication and application of Zn functionalized copolymer monolithic column for pipette tip micro-solid phase extraction of 4 polycyclic aromatic hydrocarbons in edible oil.

The contamination of polycyclic aromatic hydrocarbons (PAHs) in edible oil is a health threat. Thus, trace analysis of PAHs is of high necessity. Based on the efficient adsorption of PAHs on Zn metal cluster, a Zn functionalized copolymer monolithic column was rationally designed for pipette tip micro-solid phase extraction (μ-SPE).

Preparation and application of a nanocomposite of dopamine modified zirconium metal organic framework and polythiophene for solid-phase microextraction/gas chromatography of phenols released from polycarbonate materials.

The zirconium metal-organic framework (MOF) UiO-66 was modified by dopamine (DA) and electrodeposited with Poly (3,4-ethylenedioxothiophene) (PEDOT) on an etched stainless steel wire to prepare a UiO-66-DA/PEDOT nanocomposite coating. The coating was characterized by scanning electron microscopy, energy dispersive spectrometer, Fourier transform infrared and thermogravimetric analysis, respectively. The coating has high specific surface area and more porous structure, which can be used to extract eight phenols, including 2-chlorophenol, o-cresol, m-cresol, 2, 4-dichlorophenol, 4-tert-butylphenol, 4-chlorophenol, 4-tert-octylphenol and α-naphthol.

Simultaneous detection of eight phenols in food contact materials after electrochemical assistance solid-phase microextraction based on amino functionalized carbon nanotube/polypyrrole composite.

An electrochemical assistance solid-phase microextraction (EA-SPME) was developed based on amino functionalized multi-walled carbon nanotube/polypyrrole (MWCNTs-NH/PPy) composite coating. It was applied for the extraction of eight phenols in food contact material, including 2-chlorophenol, o-cresol, m-cresol, 2,4-dichlorophenol, 4-tert-butylphenol, 4-chlorophenol, 4-tertoctylphenol and alpha-naphthol. MWCNTs-NH/PPy coating was characterized by scanning electron microscopy, transmission electron microscope, X-ray energy spectrometer, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis.

Magnetic FeO@SiO@β-cyclodextrin for solid phase extraction of methyl parathion and fenthion in lettuce samples.

In this study, magnetic Fe3O4@SiO2@β-cyclodextrin copolymerized microparticles were synthesized and applied for the extraction of methyl parathion and fenthion in lettuce samples followed by HPLC-UV detection. The magnetic β-cyclodextrin copolymerized microparticles were prepared by dispersion polymerization with acryloyl β-cyclodextrin as the functional monomer and ethylene glycol dimethyacrylate as the crosslinker. The composite magnetic microparticles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, magnetic measurement, and thermogravimetric analysis, and used as the adsorbent of magnetic solid-phase extraction (MSPE) for methyl parathion and fenthion.

Moisture-sensitive metal-organic framework constructed from cobalt and 4-(4-pyridyl) benzoic acid for dispersive solid-phase extraction of polycyclic aromatic hydrocarbons in apple.

A moisture-sensitive metal-organic framework Co (pybz) ·2DMF was synthesized and applied as the adsorbent of dispersive solid-phase extraction. The structure changed after water treatment due to the fact that two chelate carboxylate groups on the skeleton were transformed to monodentate because of the coordination of water molecules. The material showed good adsorption for fluorene, phenanthrene, fluoranthene, and pyrene in water because of the π-π conjugation and π-complexation effects.

A polythiophene/UiO-66 composite coating for extraction of volatile organic compounds migrated from ion-exchange resins prior to their determination by gas chromatography.

A Poly (3,4-ethylenedioxothiophene) (PEDOT)/UiO-66 composite was electrodeposited on an etched stainless-steel wire as head-space solid-phase microextraction (HS-SPME) coating. A robust, well controlled thickness, and uniform coating of metal organic framework composites can be realized by the electrodeposited strategy. The incorporated UiO-66 not only enhanced the uniformity and stability of the composite coating, but also effectively decreased the stacking phenomenon of PEDOT and improved its extraction efficiency, which was over 100 times higher than that of the PEDOT coating without UiO-66.

Fe O nanoparticles coated with polyhedral oligomeric silsesquioxanes and β-cyclodextrin for magnetic solid-phase extraction of carbaryl and carbofuran.

In this study, porous sandwich structure Fe O nanoparticles coated by polyhedral oligomeric silsesquioxanes and β-cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe O nanoparticles coated with polyhedral oligomeric silsesquioxanes and β-cyclodextrin were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high-performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple.

A nanocomposite consisting of etched multiwalled carbon nanotubes, amino-modified metal-organic framework UiO-66 and polyaniline for preconcentration of polycyclic aromatic hydrocarbons prior to their determination by HPLC.

A polyaniline composite doped with etched multi-walled carbon nanotubes and UiO-66-NH was prepared by electropolymerization. It was used as a sorbent to extract the polycyclic aromatic hydrocarbons (PAHs) phenanthrene, fluoranthene and pyrene. Its surface morphology, crystal structure and capability of adsorbing PAHs were characterized by scanning electron microscopy, X-ray photoelectron spectrometry, Fourier transform infrared spectrometry and zeta potentiometry.

Adsorption Behavior of Polycyclic Aromatic Hydrocarbons on Zn-Based Coordination Cluster Zn: Competition, Synergy, and Mechanism.

In this work, adsorption behaviors of pyrene (PYR), fluoranthene (FLT), phenanthrene (PHE), and fluorene (FLU) on the coordination cluster [Zn(HL)](NO)]·8HO·2CHOH (Zn) were studied. The adsorption mechanism and spectrum analyses revealed that the synergistic effect of hydrophobic interaction, π-π stacking, and N-H···π interaction played a crucial role during the adsorption process. The maximum adsorption capacities of PYR, FLT, PHE, and FLU were 406.

One-pot preparation of an acryloyled β-cyclodextrin-silica hybrid monolithic column and its application for determination of carbendazim and carbaryl.

This work describes, for the first time, an acryloyled β-cyclodextrin hybrid monolith column was synthesized, under aqueous-phase conditions, and used for solid-phase microextraction of carbendazim and carbaryl. The monolithic column was characterized using scanning electron microscopy, nitrogen adsorption-desorption, thermogravimetric analysis and Fourier transform infrared spectroscopy, and used as the adsorbent for solid phase microextraction (SPME) of carbendazim and carbaryl. After optimization of the SPME conditions, a simple and sensitive SPME-HPLC method was developed for the determination of carbendazim and carbaryl in leafy vegetables.

A Selective Joint Determination of Salicylic Acid in Actinidia chinensis Combining a Molecularly Imprinted Monolithic Column and a Graphene Oxide Modified Electrode.

A new combination between selective polymer monolith microextraction (PMME) and sensitive differential pulse voltammetry (DPV) was developed for the determination of the phytohormone salicylic acid (SA) in Actinidia chinensis. A molecularly imprinted monolithic column (MIMC) thermally in-situ polymerized in a micropipette tip by using SA as a template, 4-vinyl pyridine (4-VP) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in the mixed porogen of toluene and dodecanol, was employed for the microextraction of SA. The prepared MIMC was characterized by a Fourier transform infrared spectrometer (FI-TR), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA).

Preparation of an acryloyl β-cyclodextrin-silica hybrid monolithic column and its application in pipette tip solid-phase extraction and HPLC analysis of methyl parathion and fenthion.

An acryloyl β-cyclodextrin-silica hybrid monolithic column for pipette tip solid-phase extraction and high-performance liquid chromatography determination of methyl parathion and fenthion has been prepared through a sol-gel polymerization method. The synthesis conditions, including the volume of cross-linker and the ratio of inorganic solution to organic solution, were optimized. The prepared monolithic column was characterized by thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy.

Magnetic Solid-Phase Extraction of N,N-Diethyl-m-Toluamide From Baby Toilet Water Prior to its HPLC-UV Detection.

Fe3O4@MIL-100 (MIL, Material Institut Lavoisier) core-shell magnetic microspheres were prepared and applied as the sorbent for the magnetic solid phase extraction (MSPE) of N,N-diethyl-m-toluamide (DEET) in baby toilet water for the first time. The synthesized magnetic metal-organic frameworks were characterized by transmission electron microscope, infrared spectroscopy and thermogravimetric analysis. The functionalized magnetic microparticles showed excellent dispersibility in aqueous solution.

A novel dispersive solid-phase extraction method using metal-organic framework MIL-101 as the adsorbent for the analysis of benzophenones in toner.

Metal-organic frameworks (MOFs) have been paid widespread attention in the field of adsorption and separation materials due to its porosity, large specific surface area, unsaturated metal-ligand sites and structural diversity. In this study, the green powder MIL-101 was synthesized and used for the extraction of benzophenone, 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxy-benzophenone from toner samples for the first time. The synthesized MIL-101 was characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry and nitrogen adsorption porosimetry.

Preparation and application of a novel electrochemical sensing material based on surface chemistry of polyhydroquinone.

A new analogue of polydopamine (PDA), i.e., polyhydroquinone (PH2Q), was polymerized and its surface chemistry was studied by different ways of characterization.

Preparation of 2,4-dichlorophenoxyacetic acid imprinted organic-inorganic hybrid monolithic column and application to selective solid-phase microextraction.

An organic-inorganic hybrid molecular imprinting monolith (HMIM) has been prepared, characterized and applied for the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) in rice with high-performance liquid chromatography-photodiodes array detector (HPLC-PAD). By optimizing the polymerization conditions, such as the volume ratio of the inorganic alcoholysate and organic part, the 2,4-D-HMIM was synthesized in a micro pipette tip using acrylamide as the functional monomer, ethylene dimethacrylate as the cross-linker and methanol as the porogenic solvent. The morphology of the monolith was studied by scanning electronmicroscopy and Fourier transform infrared spectra.

A molecularly imprinted organic-inorganic hybrid monolithic column for the selective extraction and HPLC determination of isoprocarb residues in rice.

An IPC-imprinted (IPC is isoprocarb) poly(methacrylic acid)/SiO2 hybrid monolithic column was prepared and applied for the recognition of the template. The hybrid monolithic column was synthesized in a micropipette tip using methyltrimethoxysilane as the inorganic precursor, 3-(methacryloxy)propyltrimethoxysilane as the coupling agent, and ethylene glycol dimethacrylate as the cross-linker. The synthesis conditions, including the porogenic solvent, coupling agent, volume ratio of the inorganic alcoholysate and organic part, were optimized.

Electrochemical reduction and voltammetric determination of metronidazole at a nanomaterial thin film coated glassy carbon electrode.

Simple and sensitive electrochemical method for the determination of metronidazole, based on a nanostructured film coated glassy carbon electrode (GCE), is described. Multi-walled carbon nanotubes (MWNT) was dispersed into water in the presence of a hydrophobic surfactant to give very stable and homogeneous MWNT suspension, and a MWNT-film coated GCE was achieved via evaporating solvent. Metronidazole yields a well-defined reduction peak whose potential is -0.

The effect of cetyltrimethyl ammonium bromide on the electrochemical determination of thyroxine.

Electrochemical behavior of thyroxine at a polyvinylpyrrolidone modified carbon paste electrode in the presence of cetyltrimethyl ammonium bromide was described. Thyroxine underwent totally irreversible oxidation at this system and a well-defined peak at 0.42 V was obtained.

Effects of surfactants on the electroreduction of dioxygen at an acetylene black electrode.

An acetylene black electrode modified by an adsorbed cationic surfactant, cetyltrimethylammonium bromide (CTAB), was developed. The influences of various types of surfactants on the electroreduction of O2 were investigated. It was demonstrated that a cationic surfactant, CTAB, on the surface of the electrode could significantly decrease the overpotential of dioxygen reduction, and the reduction peak current of O2 was also remarkably increased.

Electrocatalytic reduction of chloramphenicol at multiwall carbon nanotube-modified electrodes.

A multiwall carbon nanotube-modified glassy carbon (GC) electrode was employed for the investigation of chloramphenicol (CAP) reduction. Carbon nanotube coating can greatly lower the overpotential of the electrochemical reduction of CAP and promote the electrode reaction. CAP undergoes an irreversible reduction process in phosphate buffer by the modified electrode.