Caina Jiao

Graphene oxide framework: An adsorbent for solid phase extraction of phenylurea herbicides from water and celery samples

1,4-Phenyldiboronic acid (1,4-PDBA) linked graphene oxide framework (GOF) was prepared via an one-step, catalyst-free and hydrothermal route. To evaluate its adsorption performance, the prepared GOF was served as an adsorbent for solid phase extraction of phenylurea herbicides (PUHs) from water and celery samples prior to their determination by high performance liquid chromatography. The results indicated that GOF exhibited excellent adsorption capacity for the target PUHs. Under the optimum conditions, the method showed high recoveries ranged from 86.0% to 112.0%, low relative standard deviations (<5.4%) and low limits of detection ranged from 0.01 to 0.02ngmL-1 for water and 0.025-0.050ngg-1 for celery sample, respectively. These results indicated the great application potential of GOF in the enrichment of organic pollutants from different matrix samples.

Preparation of a Co-doped hierarchically porous carbon from Co/Zn-ZIF: An efficient adsorbent for the extraction of trizine herbicides from environment water and white gourd samples.

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%.

Magnetic porous carbon derived from a Zn/Co bimetallic metal–organic framework as an adsorbent for the extraction of chlorophenols from water and honey tea samples

A novel magnetic porous carbon derived from a bimetallic metal-organic framework, Zn/Co-MPC, was prepared by introducing cobalt into ZIF-8. Magnetic porous carbon that possesses magnetic properties and a large specific surface area was firstly fabricated by the direct carbonization of Zn/Co-ZIF-8. The prepared magnetic porous carbon material was characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, N2 adsorption, and vibrating sample magnetometry. The prepared magnetic porous carbon was used as a magnetic solid-phase extraction adsorbent for the enrichment of chlorophenols from water and honey tea samples before high-performance liquid chromatography analysis. Several experimental parameters that could influence the extraction efficiency were investigated and optimized. Under the optimum conditions, good linearities (r > 0.9957) for all calibration curves were obtained with low limits of detection, which are in the range of 0.1-0.2 ng mL(-1) for all the analytes. The results showed that the prepared magnetic porous carbon had an excellent adsorption capability toward the target analytes.

Preparation of a magnetic porous organic polymer for the efficient extraction of phenylurea herbicides

A magnetic porphyrin-based porous organic polymer (M-PPOP) with good porosity, high surface area and strong magnetism was prepared and employed as the adsorbent for the magnetic solid phase extraction of the phenylurea herbicides (metoxuron, monolinuron, chlorotoluron, and buturon) from bottled grape juice and tomato samples prior to their determination by high performance liquid chromatography. Under the optimized conditions, the developed method exhibited a good linear range, low limits of detection, low relative standard deviations (<6.8%), good method recoveries between 80.8% and 117%, and high enrichment factors (51-106). For a better elucidation of the adsorption of the M-PPOP towards the analytes, the extraction performance of the M-PPOP for different types of organic compounds including polycyclic aromatic hydrocarbons, phenylurea insecticides, phenylurea herbicides and phenols was studied. The results indicated that the π- stacking, hydrogen-bonding and hydrophobic interactions between the M-PPOP and the analytes played a main role for the adsorption. The results revealed that the M-PPOP material had a great potential for the enrichment of more organic pollutants from real samples.

Solid phase extraction of carbamate pesticides with banana peel derived hierarchical porous carbon prior to high performance liquid chromatography

In this work, biomass derived hierarchical porous carbon (BHPC) was prepared via a facile, cost-effective and green route by carbonizing banana peel waste. Textural characterization shows that the material possesses hierarchical pores and a large Brunauer–Emmett–Teller surface area of 561.8 m2 g−1. The BHPC was used as a solid phase extraction sorbent for the enrichment of carbamate pesticides from cucumber and watermelon samples coupled with high-performance liquid chromatography with a diode array detector. Under the optimal conditions, good linearity was obtained in the concentration range of 0.2–80.0 ng g−1 for propoxur and bassa, and 0.5–80 ng g−1 for isoprocarb, with a correlation coefficient (r) larger than 0.9969. The limits of detection of the method were in the range of 0.05–0.20 ng g−1. The results show that BHPC has great potential to be applied for the isolation and preconcentration of organic analytes from complex matrices.

RETRACTED: Preparation of magnetic mesoporous poly-melamine-formaldehyde composite for efficient extraction of chlorophenols

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors and the Editor-in-Chief. The article reports the synthesis of basically the same adsorbent as reported by the authors in another publication published in Microchimica Acta, 185 (2018) 19 https://doi.org/10.1007/s00604-017-2593-5. Although the adsorbent material was used to enrich different analytes in the two papers, the description about the preparation of the material is similar in both papers and figures 2C, 3B and 3C in the Talanta paper obtained from the material characterization are identical to Figures 1C, 2A, and 2B in the Microchimica Acta paper. Both publications do not refer to each other. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process