Hollow porous dummy molecularly imprinted polymer as a sorbent of solid-phase extraction combined with accelerated solvent extraction for determination of eight bisphenols in plastic products

Dissolution-precipitation method concatenated sodium alginate/MOF-derived magnetic multistage pore carbon magnetic solid phase extraction for determination of antioxidants and ultraviolet stabilizers in polylactic acid food contact plastics

Antioxidants and UV stabilizers have some endocrine disrupting effects and liver toxicity. Both types of additives are still widely used in food contact plastics to improve the durability of plastic products. However, efficient and rapid detection of antioxidants and UV stabilizers has been a challenge due to the complexity of the plastic matrix and the low content of antioxidants and UV stabilizers. In this study, a sodium alginate/MOF-derived magnetic multistage pore carbon material (MIL-101(Fe)/SA-CAs) was developed, having the merits of abundant multistage pore structure, large specific surface area, and good magnetic separation properties. Thus, this material was selected as the sorbent for magnetic solid-phase extraction combined with a dissolution-precipitation method for the extraction and purification of antioxidants and UV stabilizers from polylactic acid food contact plastics. The extraction parameters such as sorbent type, sorbent dosage, sample solution pH, ionic strength, sorption time, elution solution type, volume, and time were investigated. Under the optimized conditions, all the analytes determined by UPLC-MS/MS showed good linear range (r > 0.99), detection limit (0.023-3.105 ng g-1), accuracy (70.6-102.3 %), and reproducibility (RSD<9.8 %). Further, the developed method was applied to determine the antioxidants and UV stabilizers in polylactic acid lunch boxes and straws, showing excellent applicability. The results showed that the antioxidants and UV stabilizers were detected in some of the samples, with a maximum detection of antioxidant 1010 at 7297 ng g-1. This study provided a sensitive, efficient, and environmentally friendly method for antioxidants and UV stabilizers in polylactic acid food contact plastics. The ideas for the design of environmentally friendly metal-organic frameworks and biomass composite multifunctional materials would promise in the sample pretreatment field for the emerging contaminants.

Simultaneous targeted and non-targeted analysis of plastic-related contaminants in e-waste impacted soil in Agbogbloshie, Ghana

An LC-MS based analytical method was developed and validated for the simultaneous targeted analysis and suspect screening of plastic-related contaminants in e-waste impacted soils. Satisfactory recoveries (97 ± 13 %) were achieved using ultrasound-assisted extraction for 14/15 of the targeted analytes (7 bisphenols and 8 plasticizers) in a range of agricultural and non-agricultural soils. The method was applied to 53 soil samples collected in May 2015 in the region of Agbogbloshie (Ghana) at e-waste facilities (incl. Dump, trade, and burn sites), neighboring non-agricultural (incl. upstream, downstream, and community) and agricultural fields, and at two control agricultural sites away from e-waste recycling facilities. Bisphenol A (BPA) and bis(2-ethylhexyl) phthalate (DEHP) were the two dominant contaminants in e-waste soil (with concentrations up to 48.7 and 184 μg g-1, respectively), especially at the trade site, where e-waste was sorted and dismantled. The non-targeted workflow was successfully applied to identify additional plastic-related contaminants previously unreported in e-waste impacted soils, including bis(2-propylheptyl) phthalate, diisononyl phthalate, trioctyl trimellitate, 4-dodecylbenzenesulfonic acid, perfluorooctanesulfonic acid, perfluorobutanesulfonic acid, diphenyl phosphate, and triethylene glycol monobutyl ether. The agricultural soils surrounding the e-waste sites were also contaminated by plastic-related chemicals (especially DEHP), highlighting the impact of e-waste activities on the surrounding agricultural system.

A novel pencil graphite electrode modified with an iron-based conductive metal-organic framework exhibited good ability in simultaneous sensing bisphenol A and bisphenol S

Bisphenol A (BPA) and its substitute bisphenol S (BPS) are desirable materials widely used in manufacturing plastic products but can pose carcinogenic risks to humans. A new conductive iron-based metal-organic framework (Fe-HHTP)-modified pencil graphite electrode (PGE) for electrochemically sensing BPA and BPS was prepared and fully characterized by SEM, TEM, FT-IR, XRD, and XPS. Results showed that the optimal conditions for preparing Fe-HHTP/PGE were a pH of 6.5, a Fe-HHTP concentration of 2 mg·mL-1, a deposition potential of 0 V, and a deposition time of 100 s. The Fe-HHTP/PGE prepared under such conditions harbored a significant electrocatalytic activity with a detection limit of 0.8 nM for BPA and 1.7 nM for BPS (S/N = 3). Correspondingly, the electrochemical response current was linearly correlated to BPA and BPS, ranging from 0.01 to 100 μM. Fe-HHTP/PGE also obtained satisfactory recoveries by 93.8-102.1% and 96.0-101.3% for detecting BPA and BPS in plastic food packaging samples. Our work has provided a novel electrochemical tool to simultaneously detect BPA and BPS in food packaging samples and environmental matrixes.

Recent Advances in Non-Targeted Screening of Compounds in Plastic-Based/Paper-Based Food Contact Materials

Ensuring the safety of food contact materials has become a pressing concern in recent times. However, detecting hazardous compounds in such materials can be a complex task, and traditional screening methods may not be sufficient. Non-targeted screening technologies can provide comprehensive information on all detectable compounds, thereby supporting the identification, detection, and risk assessment of food contact materials. Nonetheless, the non-targeted screening of food contact materials remains a challenging issue. This paper presents a detailed review of non-targeted screening technologies relying on high-resolution mass spectrometry for plastic-based and paper-based food contact materials over the past five years. Methods of extracting, separating, concentrating, and enriching compounds, as well as migration experiments related to non-targeted screening, are examined in detail. Furthermore, instruments and devices of high-resolution mass spectrometry used in non-targeted screening technologies for food contact materials are discussed and summarized. The research findings aim to provide a theoretical basis and practical reference for the risk management of food contact materials and the development of relevant regulations and standards.

β-cyclodextrin-functionalized magnetic graphene oxide for the efficient enrichment of bisphenols in milk and milk packaging

In this work, β-cyclodextrin-functionalized magnetic graphene oxide (NiFe₂O₄@GO@β-CD) was synthesized and employed as magnetic solid-phase extraction adsorbent for the extraction of bisphenols before high performance liquid chromatography analysis. The modification of β-cyclodextrin could enhance the adsorption performance of NiFe₂O₄@GO@β-CD towards bisphenols through the host-guest interaction and hydrogen-bond interaction. Under the optimal conditions, good linearities between peak area and concentration of bisphenols (1 - 300 μg L^-1, r ≥ 0.9989) were obtained with the limits of detection (S/N = 3) in the range of 0.050 - 0.10 μg L^-1. The recoveries of bisphenols in milk and milk packaging ranged from 78.0% to 101.6%. Moreover, NiFe₂O₄@GO@β-CD showed stable chemical properties and good reusability with the recoveries of bisphenols remained above 80.0% after 12 MSPE cycles. The adsorption characteristics of NiFe₂O₄@GO@β-CD towards bisphenols fitted well with the pseudo-second-order kinetic model and Langmuir model. The hydrogen-bond interaction, π-π interaction, host-guest interaction and electrostatic interaction between sorbent and bisphenols played important role during the adsorption process. The developed method showed potential applications for the analysis of trace bisphenols in milk and milk packaging.

Hollow porous molecularly imprinted polymers as emerging adsorbents

Hollow porous molecularly imprinted polymers (HPMIPs) are identified as promising adsorbents with many advantageous properties (e.g., large number of imprinted cavities, highly accessible binding sites, controllable pore structure, and fast mass transfer). Because of such properties, HPMIPs can exhibit improved binding capacity and kinetics to make analyte molecules readily interact with a greater number of recognition sites on the imprinted shell. This review highlights the synthesis and utility of HPMIPs as adsorbents to cover diverse targets of interest (e.g., endocrine disrupting chemicals, pharmaceuticals, pesticides, and heavy metal ions). The overall potential of HPMIPs is thus discussed in the context of analytical chemistry with particular focus on the efficient extraction of trace-level targets from complex matrices.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

Membrane Emulsification Process as a Method for Obtaining Molecularly Imprinted Polymers

The membrane emulsification process (ME) using a metallic membrane was the first stage for preparing a spherical and monodisperse thermoresponsive molecularly imprinted polymer (TSMIP). In the second step of the preparation, after the ME process, the emulsion of monomers was then polymerized. Additionally, the synthesized TSMIP was fabricated using as a functional monomer N-isopropylacrylamide, which is thermosensitive. This special type of polymer was obtained for the recognition and determination of trace bisphenol A (BPA) in aqueous media. Two types of molecularly imprinted polymers (MIPs) were synthesized using amounts of BPA of 5 wt.% (MIP-2) and 7 wt.% (MIP-1) in the reaction mixtures. Additionally, a non-imprinted polymer (NIP) was also synthesized. Polymer MIP-2 showed thermocontrolled recognition for imprinted molecules and a higher binding capacity than its corresponding non-imprinted polymer and higher than other molecularly imprinted polymer (MIP-1). The best condition for the sorption process was at a temperature of 35 °C, that is, at a temperature close to the phase transition value for poly(N-isopropylacrylamide). Under these conditions, the highest levels of BPA removal from water were achieved and the highest adsorption capacity of MIP-2 was about 0.5 mmol g-1 (about 114.1 mg g-1) and was approximately 20% higher than for MIP-1 and NIP. It was also observed that during the kinetic studies, under these temperature conditions, MIP-2 sorbed BPA faster and with greater efficiency than its non-imprinted analogue.

Determination and occurrence of bisphenol A and thirteen structural analogs in soil

Bisphenol A is a phenolic plasticizer used in the production of various plastic products. Its endocrine-disrupting effects on ecological and human health lead to replacement with its structural analogs. The occurrence of these analogs in the soil environment, which is an important sink for bisphenols, has been rarely reported. In this study, a robust method was developed to determine bisphenol A and 13 analogs in soil using accelerated solvent extraction combined with in-line purification for fast and efficient extraction and ultra-performance liquid chromatography-tandem mass spectrometry for simultaneous and accurate quantification. The method detection limits of 14 bisphenols were between 0.01 and 0.39 ng g^-1, and the recoveries were in the range of 80%-120%. The developed method was applied to 29 agricultural and urban soil samples from 21 provinces in China, and 12 bisphenols were detected. Among them, the contents of bisphenol A, F, and P were up to 166.0, 212.9, and 78.2 ng g^-1 dry weight, respectively. The maximum concentration of bisphenol P was at least ten times higher than literature values in food and other environmental matrices. The results of this study showed that "hot spots" existed for bisphenol pollution in soil and that further investigations were necessary to avoid regrettable substitutions.

Nanoparticles Based Extraction Strategies for Accurate and Sensitive Determination of Different Pesticides

Sample preparation methods have become indispensable steps in analytical measurements not only to lower the detection limit but also to eliminate the matrix effect although more sophisticated instruments are being commonly used in routine analyses. Solid phase extraction (SPE) is one of the main extraction/preconcentration methods used to extract and purify target analytes along with simple and rapid procedures but some limitations have led to seek for an easy, sensitive and fast extraction methods with analyte-selective sorbents. Nanoparticles with different modifications have been used as spotlight to enhance extraction efficiency of target pesticides from complicated matrices. Carbon-based, metal and metal oxides, silica and polymer-based nanoparticles have been explored as promising sorbents for pesticide extraction. In this review, different types of nanoparticles used in the preconcentration of pesticides in various samples are outlined and examined. Latest studies in the literature are discussed in terms of their instrumental detection, sample matrix and limit of detection values. Novel strategies and future directions of nanoparticles used in the extraction and preconcentration of pesticides are also discussed.

One-pot fabrication of lignin-based aromatic porous polymers for efficient removal of bisphenol AF from water

To remove the bisphenol AF (BPAF) from aqueous solution, two different types of lignin-based aromatic porous polymers (LAPP-1 and LAPP-2) were fabricated via one-pot crosslinking of lignin with 1,4-dichloroxylene and 4,4'-bis(chloromethyl)-1,1'-biphenyl, respectively. The successful synthesis of LAPPs was confirmed by FTIR and XPS, SEM, TEM and N₂ adsorption-desorption analysis. Then, batch adsorption experiments were conducted to investigate adsorption properties toward BPAF. Based on the results, the adsorption processes were in accordance with the pseudo-second-order kinetic model and the Freundlich isotherm model, and the thermodynamic studies showed that the adsorption was a spontaneous and exothermic process. It is remarkable that LAPPs exhibited good adsorption performance in wide ranges of pH and ionic strength as well as in recycling process. Notably, compared to LAPP-1, LAPP-2 exhibited higher adsorption capacity for BPAF, which can be ascribed to its higher porosity and content of aromatic ring. Moreover, the comprehensive analysis of experimental and theoretical results indicated that the π-π interactions and pore adsorption may jointly drive the uptake process of BPAF. Considering the simple fabrication method employed and excellent BPAF adsorption performance, LAPPs provided new insights into the development of advanced lignin-based adsorbents for removal of BPAF from water.

Application of the liquid-liquid dispersed microextraction based on phase transition behavior of temperature sensitive polymer to rapidly detect 5 BPs in food packaging

In this paper, temperature sensitive polymer p(MAH-β-CD-co-NIPAM) was used as extraction in DLLME, because its phase transition behavior can be observed at room temperature due to Hofmeister and non-co-solvent effect. The whole pretreatment process is simple and fast, and the extraction process did not require dispersant to assist dispersion and centrifugation to collect the adsorbent. A new analytical method based on DLLME coupled with HPLC-UV was developed to detect five types of BPs in milk and take-out packaging. The limits of detection ranged from 0.44 to 1.60 ng mL^-1 (S/N = 3). The relative recoveries of 5 BPs in food packaging were in the range of 91.08-108.04%.

Extraction optimization of accelerated solvent extraction for eight active compounds from Yaobitong capsule using response surface methodology: Comparison with ultrasonic and reflux extraction

This work described the development of a novel method for simultaneous extraction of eight active compounds (including catechin, albiflorin, paeoniflorin, ferulic acid, ginsenoside Rg1, tetrahydropalmatine, ginsenoside Rb1 and osthole) from Yaobitong capsule by accelerated solvent extraction (ASE). Response surface methodology (RSM) with desirability functions was employed to optimize the extraction conditions yielding the optimal conditions of ASE (extraction time 8 min, extraction temperature 80 °C, extraction solvent 70% methanol and flushing volume 100%). A high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) method was developed and validated for simultaneous quantification of the eight compounds in Yaobitong capsule. The values of correlation coefficient (R) were satisfactory between 0.9992 and 0.9999 over the linear concentration range of 0.5-1000 μg mL^-1. It was found that the limits of detection (LODs) and the limits of quantification (LOQs) for the eight active compounds were 0.10-2.90 μg•mL^-1 and 0.30-9.40 μg•mL^-1, respectively. The recoveries of the eight main active compounds in Yaobitong capsule were in the range of 93.31%-106.22%. And the contents of the analytes extracted by ASE under the optimal conditions were compared to traditional solvent extraction methods, such as ultrasonic and reflux extraction. The results indicated that the ASE method proved to be more suitable for the extract of active compounds in Yaobitong capsule, which could obtain higher extraction efficiency. At last, the proposed method was applied to analyze ten batches of actual samples, which provided high extraction efficiency and had wide potential application in the analysis of traditional Chinese medicines.