Synthesis of a molecularly imprinted polymer for the isolation of 1-hydroxypyrene in human urine

Fast magnetic solid-phase extraction using an Fe3O4-NH2@MOF material for monohydroxy polycyclic aromatic hydrocarbons in urine of coke-oven workers

In this work, a magnetic material (Fe3O4-NH2@MIL-101) was successfully prepared, and the material was used as a sorbent for the magnetic solid-phase extraction (MSPE) of trace level monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) from urine samples for the first time. The target analytes were quantified by high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD). The MSPE key factors, which include the amount of adsorbent, extraction time, pH, the effect of salt, eluting solutions and eluant volume, were systematically optimized. Under the optimized conditions, the developed method showed good linearity (0.03-200 ng mL-1), low limits of detection (0.016-0.042 ng mL-1, signal-to-noise ratio = 3) and satisfactory repeatability (relative standard deviation ≤ 10.1%, n = 5). The method showed stable average recoveries ranging from 78.3% to 112.9% and the enrichment factors were 9 to 15. Besides the satisfactory method parameters, the total MPSE process could be completed in no more than 5 minutes. These results indicated that Fe3O4-NH2@MOF based MSPE was a simple, efficient and fast method which was suitable for MSPE of OH-PAHs from urine samples.

Ultrasound-assisted dispersive micro-solid-phase extraction based on N-doped mesoporous carbon and high-performance liquid chromatographic determination of 1-hydroxypyrene in urine samples

In this research, a new ultrasound-assisted dispersive micro-solid-phase extraction method based on N-doped mesoporous carbon sorbent followed by high-performance liquid chromatography equipped with diode array detector for trace measurement of 1-hydroxypyrene as a metabolite of exposure to polycyclic aromatic hydrocarbons was optimized. Herein, the hard template method was used for the preparation of N-doped mesoporous carbon sorbent. The prepared sorbent was characterized using the Brunauer-Emmett-Teller method, transmission electron microscopy, and elemental analysis. Parameters affecting the extraction of the target metabolite were investigated using the Box-Behnken design method. Considering optimum parameters, the plotted calibration curve for 1-hydroxypyrene was linearly correlated with the concentration span of 0.1-50 μg/L for urine media. The accuracy of the optimized procedure was examined through the relative recovery tests on the fortified urine specimens. The relative recoveries fell between 95 and 101%. The method detection limit of the proposed procedure was also calculated to be 0.03 μg/L.

Assay of 1-hydroxypyrene via aggregation-induced quenching of the fluorescence of protamine-modified gold nanoclusters and 9-hydroxyphenanthrene-based sensitization

This work describes a method for the determination of 1-hydroxypyrene (OH-Py) via aggregation-induced quenching of the emission of protamine-coated gold nanoclusters using 9-hydroxyphenanthrene (OH-Phe) as a sensitizer to boost the emission efficiency of nanoprobe. Under optimum conditions, the drop in fluorescence intensity at excitation/emission wavelengths of 300/596 nm is proportional to the concentrations of OH-Py in the range from 1.0 to 65 nM. The relative standard deviations are 4.2, 2.4 and 1.9% (for n = 11) at concentration levels of 8.0, 32 and 48 nM of OH-Py, respectively. The detection limit is 0.3 nM which is much lower than that of some previously reported methods. The recoveries from urine samples spiked with OH-Py ranged between 94.4 and 98.8%. Graphical abstract 1-Hydroxypyrene (OH-Py) can trigger the aggregation of protamine-gold nanoclusters (PRT-AuNCs), resulting in the emission quenching of PRT-AuNCs. 9-Hydroxyphenanthrene (OH-Phe) can boost the emission efficiency of nanoprobe. Thereby, a highly sensitive assay of OH-Py was established.

Selective Fenton-like oxidation of methylene blue on modified Fe-zeolites prepared via molecular imprinting technique

A facile strategy to increase the selectivity of heterogeneous Fenton oxidation is investigated. The increase was reached by increasing selective adsorption of heterogeneous Fenton catalyst to a target pollutant. The heterogeneous Fenton catalyst was prepared by a two-step process. First, zeolite particles were imprinted by the target pollutant, methylene blue (MB), in their aggregations, and second, iron ions were loaded on the zeolite aggregations to form the molecule imprinted Fe-zeolites (MI-FZ) Fenton catalyst. Its adsorption amount for MB reached as high as 44.6 mg g^-1 while the adsorption amount of un-imprinted Fe-zeolites (FZ) is only 15.6 mg g^-1. Fenton removal efficiency of MI-FZ for MB was 87.7%, being 33.9% higher than that of FZ. The selective Fenton oxidation of MI-FZ for MB was further confirmed by its removal performance for the mixed MB and bisphenol A (BPA) in solution. The removal efficiency of MB was 44.7% while that of BPA was only 14.9%. This fact shows that molecular imprinting is suitable to prepare the Fe-zeolites (FZ)-based Fenton catalyst with high selectivity for removal of target pollutants, at least MB.

Electrodeposition of self-assembled poly(3,4-ethylenedioxythiophene) @gold nanoparticles on stainless steel wires for the headspace solid-phase microextraction and gas chromatographic determination of several polycyclic aromatic hydrocarbons

In this work, a novel poly(3,4-ethylenedioxythiophene)@Au nanoparticles (PEDOT@AuNPs) hybrid coating was prepared and characterized. Firstly, the monomer 3,4-ethylenedioxythiophene was self-assembled on AuNPs, and then electropolymerization was performed on a stainless steel wire by cyclic voltammetry. The obtained PEDOT@AuNPs coating was rough and showed cauliflower-like micro-structure with thickness of ∼40μm. It displayed high thermal stability (up to 330°C) and mechanical stability and could be used for at least 160 times of solid phase microextraction (SPME) without decrease of extraction performance. The coating exhibited high extraction capacity for some environmental pollutants (e.g. naphthalene, 2-methylnaphthalene, acenaphthene, fluorene and phenathrene) due to the hydrophobic interaction between the analytes and PEDOT and the additional physicochemical affinity between polycyclic aromatic hydrocarbons and AuNPs. Through coupling with GC detection, good linearity (correlation coefficients higher than 0.9894), wide linear range (0.01-100μgL^-1), low limits of detection (2.5-25ngL^-1) were achieved for these analytes. The reproducibility (defined as RSD) was 1.1-4.0% and 5.8-9.9% for single fiber (n=5) and fiber-to-fiber (n=5), respectively. The SPME-GC method was successfully applied for the determination of three real samples, and the recoveries for standards added were 89.9-106% for lake water, 95.7-112% for rain water and 93.2-109% for soil saturated water, respectively.

Pneumocandin B0-imprinted Polymer Using Surface-imprinting Technique for Efficient Purification of Crude Product

In this work, we prepared surface molecularly imprinted polymer (MIP) for selective recognition of pneumocandin B0 (PNB0). Methacrylic acid (MAA) was first grafted onto silica gel particles (SiO2) in the manner of "grafting from" by using 3-methacryloxypropyl trimethoxysilane as intermedium, and then PNB0 molecules were imprinted on the surface of the obtained particles in the presence of ethylene glycol diglycidyl ether as the cross-linker. The prepared MIP-PMAA/SiO2 was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and thermo-gravimetric analysis, which confirmed the successful grafting of MAA onto SiO2 and the grafting degree was calculated to be 12.50 wt%. The binding properties of the products were investigated and it is found that the binding process of PNB0 followed the pseudo-second-order kinetic model. The as-prepared material also displays relatively quick adsorption kinetics and decent recognition affinity toward the template over its structurally related compound.

Preparation and selective adsorption of organic pollutants by an inorganic molecular imprinted polymer

A novel inorganic molecular imprinted polymer (MIP) was synthesized by adding Al(3+) to the Fe/SiO2 gel with Acid Orange II (AO II) as the template. The MIP was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and nitrogen adsorption-desorption measurement. Compared with the non-imprinted polymer (NIP), the MIP enhanced the adsorption capacity of the target pollutants AO II. The selective adsorption capacity study indicated that the MIP adsorbed more AO II than the interferent Bisphenol A (BPA), which also has the structure of a benzene ring, thus proving the selective adsorption capacity of the MIP for template molecules AO II. In addition, the adsorption of AO II over MIP belonged to the Langmuir type and pseudo-second adsorption kinetics, and Dubinin-Radushkevich model indicates that the adsorption process of AO II over MIP and NIP are both given priority to chemical adsorption. The MIP reusability in performance was demonstrated in at least six repeated cycles.