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Highlights • DAAQ-TFP was prepared as adsorbent for extraction of BUs. • DAAQ-TFP has excellent extraction performance and adsorption capacity. • SPE-HPLC-UV was developed for the determination of BUs with low LODs. Abstract A covalent organic framework (named as DAAQ-TFP) was prepared via a fast, environmentally-friendly, and easy-to-perform grinding method with 2,6-diaminoanthraquinone (DAAQ) and 1,3,5-triformylphloroglucinol (TFP) as building blocks. The DAAQ-TFP possesses large surface area, high porosity, good thermochemical stability, abundant O atoms and N-H groups, which render it great potential as sorbent for some compounds. It was employed as adsorbent to extract benzoylurea insecticides (BUs) from environmental water, juice, fruit and vegetables samples, followed by their determination with high-performance liquid chromatography (HPLC). The DAAQ-TFP showed a high adsorption capacity for BUs, and the presented method provided a very low limits of detection and high method recoveries. To explore its application potential and also to clarify the possible adsorption mechanisms of the DAAQ-TFP toward BUs, it was tested to extract different types of compounds, proving that the DAAQ-TFP can serve as a superior adsorbent, and adsorption mechanism is mainly based on the π-π stacking and H bonding. [ABSTRACT FROM AUTHOR]

A covalent organic framework named TpAzo was successfully fabricated by a simple and environmentally friendly mechanochemical grinding method based on the Schiff base aldehyde-amine condensation reaction between 1,3,5-triformylphloroglucinol (Tp) and 4,4′-azodianiline (Azo), with p -toluene sulphonic acid as a molecular organizer. The TpAzo was characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The TpAzo possessed a sheet-like morphology, rich porosity and high thermal stability. The extraction performance of the TpAzo was investigated by using it as the solid phase extraction adsorbent for the extraction of benzoylurea insecticides (BUs) from juice, tomato and white radish samples prior to high performance liquid chromatographic analysis. Under the optimal conditions, a good linearity for the BUs existed in the range of 1.0–160.0 ng mL −1 for juice sample and 0.5–80.0 ng g −1 for tomato and white radish samples with the correlation coefficients of 0.9956–0.9999. The limits of detection for the analytes were 0.1–0.2 ng mL −1 for juice sample and 0.05–0.1 ng g −1 for tomato and white radish samples. The method recoveries for the analytes fell in the range of 84.1%–108.6%. The adsorption mechanism of the TpAzo was investigated by using it to extract different types of organic compounds, including phthalates, phenylurea herbicides and carbamate insecticides. The results showed that the π-stacking and hydrophobic interactions between the TpAzo and the analytes played an important role for the adsorption. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a magnetic β‐cyclodextrin polymer was successfully prepared and used as an adsorbent for the magnetic solid‐phase extraction of six benzoylurea insecticides (diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, flufenoxuron, and chlorfluazuron) from honey, tomato, and environmental water samples. The influence of the main experimental conditions on the extraction was studied. Under the optimized conditions, the β‐cyclodextrin polymer@Fe3O4 showed an excellent extraction performance for the benzoylurea insecticides. A good linearity was obtained for the analytes in the range of 3.0–800 ng/g for honey samples, 0.3–160 ng/g for tomato samples, and 0.1–80.0 ng/mL for water samples, with the correlation coefficients above 0.9998. Satisfactory repeatabilities were achieved, with the relative standard deviations less than 5.7%. The limits of detection (S/N = 3) of the method for the benzoylurea insecticides were 0.2–0.8 ng/g for honey samples, 0.04–0.10 ng/g for tomato samples, and 0.02–0.05 ng /mL for water samples. The method was successfully used for the determination of the six benzoylurea insecticides residues in honey, tomato, and environmental water samples with a satisfactory result. [ABSTRACT FROM AUTHOR]

A hypercrosslinked organic polymer material (named as PPTPA) was prepared by a simple one-step self-polycondensation of triphenylamine. A series of characterization experiments, including N 2 adsorption, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, and thermogravimetric analysis, were carried out to evaluate the morphology, structure and other intrinsic properties of the PPTPA. To investigate its adsorption performance, the PPTPA was used as the solid-phase extraction adsorbent for the extraction of phenylurea herbicides from water, milk and tomato juice samples followed by high-performance liquid chromatographic analysis. Under optimum conditions, good linearity for the analytes was observed in the range of 0.05–40.0 ng mL −1 , 0.1-40.0 ng mL −1 and 0.5–40.0 ng mL −1 for water, milk and tomato juice samples, respectively. The established method also showed low limits of detection (S/N = 3) in the range of 0.008–0.01 ng mL −1 , 0.01–0.03 ng mL −1 and 0.05–0.1 ng mL −1 for water, milk and tomato juice samples, respectively. The possible adsorption mechanism of the PPTPA towards the analytes was investigated, and the results demonstrated that the hydrogen bonding was the main interaction force between the PPTPA and the analytes. It suggests that the PPTPA can serve as a promisingadsorbent for the efficient pre-enrichment of organic compounds with more hydrogen-bonding donor sites. [ABSTRACT FROM AUTHOR]

In this study, corn stalk was used to synthesize a magnetic adsorbent by pyrolysis together with KHCO3 as the chemical activator and iron(III) salt as the magnetic reagent. The characterization by scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption analysis showed that the magnetic carbon adsorbent had a structure of hierarchical pores with a high specific surface area. To evaluate its adsorption performance, the adsorbent was used for the extraction of carbamates pesticides (propoxur, isoprocarb and fenobucarb) from water and zucchini samples before high-performance liquid chromatography analysis. The result showed that the adsorbent had a good adsorption capability for the analytes. Under the optimized conditions, a good linearity for the analytes existed in the range of 0.1-100.0 ng/mL for water samples and 0.5-100.0 ng/g for zucchini samples with the correlation coefficients of 0.9992-0.9998. The limits of detection for the analytes at a signal to noise ratio of 3 were 0.03 ng/mL for water samples and 0.20-0.50 ng/g for zucchini samples. [ABSTRACT FROM AUTHOR]

In this paper, porous carbon with a highly ordered structure was synthesized using zeolite ZSM-5 as a template and sucrose as a carbon source. Through the in situ reduction of Fe 3+ , magnetic property was successfully introduced into the ordered porous carbon, resulting in a magnetic porous carbon (MPC). MPC was used as an adsorbent for the extraction of some chlorophenols (2-chlorophenol, 3-chlorophenol, 2,3-dichlorophenol and 3,4-dichlorophenol) from water and peach juice samples followed by high performance liquid chromatography-ultraviolet detection. Good linearity was observed in the range 1.0–100.0 ng mL −1 and 2.0–100.0 ng mL −1 for water and peach juice sample, respectively. The limits of detection ( S / N = 3) were between 0.10 and 0.30 ng mL −1 . The relative standard deviations were less than 5.3% and the recoveries of the method for the compounds were in the range from 87.8% to 102.3%. The results demonstrated that the MPC had a high adsorptive capability toward the four chlorophenols from water and peach juice samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] A magnetic microsphere-confined graphene Fe3O4@SiO2-G was synthesized via chemical bonding. [•] It was an efficient adsorbent for the pre-concentration of some PAHs from water sample. [•] It was more stable and could be reused for more than 30 times. [Copyright &y& Elsevier]

Abstract: In this study, a magnetic microsphere-confined graphene (Fe3O4@SiO2-G) was prepared as a novel adsorbent for the preconcentration of some phthalate esters in environmental water and soybean milk samples prior to high performance liquid chromatography analysis. The properties and morphology of the Fe3O4@SiO2-G were characterized by transmission electron microscopy and X-ray diffraction. This novel graphene-based magnetic nanocomposite showed great adsorptive ability toward the analytes. The method, which takes the advantages of both the high adsorption capacity of G and easy phase separation of the magnetic adsorbent from the sample solution, could avoid the time-consuming experimental procedures related to the traditional solid phase extraction. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the extraction time, the pH of sample solution and the desorption conditions, were investigated. Under the optimum conditions, the limits of detection (S/N=3) of the method for the compounds were between 0.07 and 0.10ngmL−1 in water samples, and between 0.15 and 0.30ngmL−1 in soybean milk samples. The relative standard deviations (RSDs) varied from 2.7% to 6.1% (n=5). The recoveries of the method were in the range between 87.2% and 109.0% for environmental water and soybean milk samples. The method is suitable to determine the five phthalate esters (diallyl phthalate, di-n-propyl-phthalate, benzyl butyl phthalate, dicyclohexyl-phthalate and diethyl-hexyl-phthalate) in environmental water and soybean milk samples. [Copyright &y& Elsevier]

A Co-doped hierarchically porous carbon (Co/HPC) was synthesized through a facile carbonization process by using Co/ZIF-8 as the precursor. The textures of the Co/HPC were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, vibration sample magnetometry and nitrogen adsorption–desorption isotherms. The results showed that the Co/HPC is in good polyhedral shape with uniform size, sufficient magnetism, high surface area as well as hierarchical pores (micro-, meso- and macropores). To evaluate the extraction performance of the Co/HPC, it was applied as a magnetic adsorbent for the enrichment of triazine herbicides from environment water and white gourd samples prior to high performance liquid chromatographic analysis. The main parameters that affected the extraction efficiency were investigated. Under the optimum conditions, a good linearity for the four triazine herbicides was achieved with the correlation coefficients ( r ) higher than 0.9970. The limits of detection, based on S/N =3, were 0.02 ng/mL for water and 0.1–0.2 ng/g for white gourd samples, respectively. The recoveries of all the analytes for the method fell in the range from 80.3% to 120.6%. [ABSTRACT FROM AUTHOR]