Magnetic solid phase extraction based on Fe3O4@SiO2@CTS nano adsorbent for the sensitive detection of trace polychlorinated biphenyls in environmental water samples

Preparation of Inorganic-Organic Hybrid Flocculant Silicon Dioxide-Chitosan-Dimethyl Diallyl Ammonium Chloride for the Treatment of Papermaking Wastewater

In order to solve the shortcomings of a single flocculant, the inorganic-organic hybrid flocculant SiO2-CTS-DMDACC was successfully prepared by grafting copolymerization of chitosan (CTS), dimethyl diallyl ammonium chloride (DMDACC), and silicon dioxide (SiO2). The performance of SiO2-CTS-DMDACC in treating papermaking wastewater was investigated, and the mechanism of the flocculation process was analyzed. The results showed that the crystallinity of chitosan was reduced due to the introduction of DMDACC and SiO2. The water solubility and thermal stability of SiO2-CTS-DMDACC with the rough porous structure were enhanced. The introduction of DMDACC enhanced the cationic properties of CTS-DMDACC compared with CTS. In addition, compared to CTS-DMDACC, the introduction of SiO2 increased the viscosity of SiO2-CTS-DMDACC. The experimental results showed that the treatment effect and the flocculation performance of SiO2-CTS-DMDACC with CTS:SiO2:DMDACC of 1:2:4 were the best and better than that of CTS at pH 7 for the treatment of papermaking wastewater. The removal rates of turbidity, COD, and NH4+-N were 99.43%, 82.92%, and 78.43%, respectively. The experimental results revealed that charge neutralization was the main mechanism of SiO2-CTS-DMDACC, and the adsorption bridging and net sweeping played supplementary roles in the treatment of papermaking wastewater.

Magnetic hypercrosslinked polymer microspheres for the detection, spatial distribution, source identification and potential risks assessment of five polycyclic aromatic hydrocarbons in city river of plateau lake, Southwest China

Polycyclic aromatic hydrocarbons (PAHs) have long been globally distributed, and almost worldwide people are exposed to varying degrees of PAHs. Aqueous medium is an important transmission route of PAHs, but the detection of PAHs in aqueous environment has been a challenge. Herein, a magnetic hypercrosslinked polymer microsphere (Fe3O4@SiO2-PS@HCP) was developed for the effective detection of PAHs. Under the effect of multiple factors (hydrophilicity, intermolecular force and molecular volume), Fe3O4@SiO2-PS@HCP shows excellent performance on the enrichment of five PAHs in aqueous environment. Fe3O4@SiO2-PS@HCP was used to capture PAHs in city river of plateau lake. In-depth data analysis showed that factory activities and traffic emissions are the main pollution sources of PAHs. Ecological, carcinogenic and non-carcinogenic risks are almost within the safe range. The carcinogenic and non-carcinogenic risks of PAHs in children are higher than adults, which needs to be taken seriously. This method breaks the dilemma that it is difficult to enrich weakly hydrophilic pollutants in aqueous media, and complements important pathways for tracing sources of pollutants and assessing associated risks. It brings methodological enlightenment into the development of environmental pollution and human health risk assessment methodology.

Tetrazine-based dynamic covalent polymers as degradable extraction materials in sample preparation

BACKGROUND

Current trends in Analytical Chemistry are highly focused on the introduction of new extraction materials with a high selectivity towards the target analytes, high extraction capacity as well as sustainable characteristics. In this context, the introduction of smart materials able to respond to an external stimulus constitutes a promising approach in the field. However, investigations regarding the development of such stimuli-responsive polymers have been basically centered on their synthesis and the control of their properties, and hardly on exploiting such properties to generate polymers that, once their extraction function is fulfilled, they can be degraded into fragments with little or negligible toxicity, or even into their constituent monomers for an efficient recycling.

RESULTS

The applicability of a degradable and recyclable dynamic covalent polymer based on the use of tetrazine as a linker was assessed as sorbent for the extraction of a group of 37 persistent organic pollutants, including 10 polycyclic aromatic hydrocarbons, 11 organochlorine pesticides, 14 polychlorinated biphenyls, and 2 antibacterial agents, from water samples. A microdispersive solid-phase extraction procedure was developed for the selective extraction of the target analytes, while their separation, determination, and quantification were achieved by gas chromatography coupled to mass spectrometry. The optimized procedure was validated for seawater and wastewater obtaining mean relative recovery values between 72 and 112 % for almost all the analytes, with satisfactory relative standard deviation values (<18 %). After extraction, the polymer could be degraded by adding the amino acid L-tyrosine, being possible a quantitative recovery of the initial functional monomer.

SIGNIFICANCE

A responsive polymer based on the chemical versatility of the tetrazine ring was used as sorbent in sample preparation providing excellent results, showing good physicochemical properties and the ability to be degraded after use. This polymer constitutes an interesting alternative to reduce chemical waste through the recycling of monomers, contributing to the development of more sustainable analytical methodologies.

Post-imprinting modification of molecularly imprinted polymer for proteins detection: A review

Inspired by protein post-translational modification (PTM), post-imprinting modification (PIM) has been proposed and developed to prepare novel molecularly imprinted polymers (MIPs), which are similar to functionalized biosynthetic proteins. The PIM involves site-directed modifications in the imprinted cavity of the MIP, such as introducing high-affinity binding sites and introducing fluorescent signal molecules. This modification makes the MIP further functionalized and improves the shortcomings of general molecular imprinting, such as single function, low selectivity, low sensitivity, and inability to fully restore the complex function of natural antibodies. This paper describes the characteristics of PIM strategies, reviews the latest research progress in the recognition and detection of protein biomarkers such as lysozyme, prostate-specific antigen, alpha-fetoprotein, human serum albumin, and peptides, and further discusses the importance, main challenges, and development prospects of PIM. The PIM technology has the potential to develop a new generation of biomimetic recognition materials beyond natural antibodies. It can be used in bioanalysis and other multitudinous fields for its unique features in molecule recognition.

Ant nest-like hierarchical porous imprinted resin-dispersive solid-phase extraction for selective extraction and determination of polychlorinated biphenyls in milk

Polychlorinated biphenyls (PCBs) are persistent toxic, organic chemicals that tend to accumulate in the food chain. This study reports the rapid and selective extraction and determination of PCBs (PCB81, 153, 105, 126, and 157) in milk samples by a dispersive solid-phase extraction (DSPE) coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). An ionic liquid-molecularly imprinted porous resin (IL-MIPPR) as a DSPE adsorbent was synthesized from m-aminophenol, formaldehyde, and 2,2'-benzidinedisulfonic acid as the monomer, crosslinker, and virtual template, respectively. The IL-MIPPR had a fast mass transfer (1.0 min) and good selectivity (imprinting factors of 1.8-3.0). The IL-MIPPR - DSPE - GC-MS/MS method exhibited good linearity (R² ≥ 0.9995), the limit of detections (LODs) < 0.6 pg/g, and the recoveries ranged from 82.8 % to 106 % with relative standard deviations ≤ 6.6 %. This method is thus better than previously reported methods in terms of the LOD, the adsorbent dosage, and the extraction time.

Design an efficient photoelectrochemical aptasensor for PCB72 based on CdTe@CdS core@shell quantum dots-decorated TiO2 nanotubes

In this work, an efficient and novel photoelectrochemical (PEC) aptasensor for 2,3',5,5'-tetrachlorobiphenyl (PCB72) was constructed based on CdTe@CdS core@shell quantum dots (CdTe@CdS QDs)-decorated TiO₂ nanotubes (TiO₂ NTs). CdTe@CdS QDs were prepared by the combination of CdTe and CdS with a proper lattice mismatch. Due to their large band offsets, core@shell QDs can reduce undesirable carrier recombination, significantly improving their charge separation efficiency. Then the synthesized CdTe@CdS QDs were modified on TiO₂ NTs (CdTe@CdS QDs/TiO₂ NTs) through electrostatic adsorption method. The as-prepared composites exhibit a wide visible light absorption range, good PEC activity and high photoelectric conversion efficiency. Also, the PEC aptasensor prepared via the immobilization of anti-PCB72 aptamer on the composites exhibits outstanding analytical performance with high sensitivity and specificity for PCB72 under visible-light irradiation, achieving a detection limit as low as 0.03 ng/L. It was also applied to detect PCB72 in four different real environmental samples with satisfactory results.

Magic extraction: solid-phase extraction and analytical pyrolysis to study polycyclic aromatic hydrocarbon and polychlorinated biphenyls in freshwater

Polycyclic aromatic hydrocarbons and polychlorinated biphenyls are commonly categorized as persistent organic pollutants. In order to analyze these pollutants, customized stationary phases are increasingly being developed and synthesized for solid-phase extraction. In this work, we tested a new solventless solid-phase extraction approach based on the use of a Magic Chemisorber® (Frontier Lab) which consists of a bead-covered polydimethylsiloxane stationary phase with a thickness of 500 µm. These devices are directly immersed into aqueous samples and then introduced into a pyrolysis-gas chromatography-mass spectrometry system equipped with a cryofocusing system for the thermal desorption and analysis of the adsorbed species. Our new method performs better than the most recent solid-phase extraction devices, with limits of detection lower than 2.7 ng/L and limits of quantification lower than 9.0 ng/L. The method was tested on standard compounds and on an environmental sample, showing the potential to characterize other chemical species besides the persistent organic pollutants, such as phthalate plasticizers and antioxidants.