Jiping Ma

New pollutants are recently identified or recognized chemical substances. They pose risks to ecosystems or human health. Many are not yet regulated or lack effective control measures. These pollutants show biological toxicity， environmental persistence， and bioaccumulation. They threaten human health. In recent years， their detection frequency in food has increased. Efficient detection technologies are urgently needed. Sample pretreatment is key for analyzing new pollutants in food. The core of pretreatment lies in the preparation and selection of adsorbent materials. Covalent organic frameworks （COFs） are porous crystalline materials. They are formed by light elements linked through covalent bonds. COFs have highly ordered crystal structures. Their pore sizes can be adjusted. Surface properties are functionalizable. They show excellent chemical and thermal stability. Composite covalent organic framework materials combine COFs with other materials. This is achieved through physical or chemical methods. The composites exhibit synergistic effects. They retain the unique properties of both COFs and the other materials. This article reviews common sample pretreatment techniques for new pollutants in food. These include solid-phase extraction （SPE）， solid-phase microextraction （SPME）， stir bar sorptive extraction （SBSE）， dispersive solid-phase extraction （DSPE）， and magnetic solid-phase extraction （MSPE）. SPE is a chromatographic technique. It removes impurities from solid or liquid samples. It also enriches target compounds. SPE offers high enrichment factors and low solvent use. It is easy to automate. SPME balances samples between solid and liquid phases. It integrates sampling， extraction， and concentration. SPME uses little or no solvent. It is simple and automatable. It can be coupled with other techniques online. SBSE evolved from SPME. It has a larger stationary phase volume and higher capacity. SBSE uses a stir bar with a magnetic core. The bar is coated with an extraction layer. Stirring ensures full contact with analytes. SBSE is solvent-free or uses minimal solvent. It is accurate， fast， and easy to automate. DSPE disperses adsorbents into sample matrices. It increases contact area between adsorbents and analytes. DSPE simplifies sample processing. It avoids sample loss. MSPE uses magnetic or magnetizable materials as adsorbents. It captures target analytes efficiently. MSPE is simple to prepare and separate. Pipette-tip-SPE （PT-SPE） is a newer technique. It packs adsorbents into pipette tips. PT-SPE is flexible， low-cost， and needs small sample volumes. This article details types of composite COF materials. These include magnetic COF （MCOF）， sponge-COF， molecularly imprinted polymer-COF （MIP-COF）， metal-organic framework-COF （MOF-COF）， and electrospun-COF. MCOF combines COFs with magnetic nanoparticles. It enables quick separation under a magnetic field. Sponge-COF grows COFs on sponge fibers. It enhances adsorption capacity and mass transfer. MIP-COF integrates molecularly imprinted polymers with COFs. It offers specific recognition sites. MOF-COF combines metal-organic frameworks with COFs. It introduces metal active sites. Electrospun-COF embeds COFs into polymer nanofibers. It improves mechanical performance and stability. These composite materials are utilized in the pretreatment of food samples， where they effectively enrich trace levels of new pollutants， including perfluoroalkyl substances， antibiotics， personal care products， endocrine disruptors， and flame retardants， within complex food matrices. When coupled with analytical techniques such as high-performance liquid chromatography （HPLC）， HPLC-tandem mass spectrometry （HPLC-MS/MS）， gas chromatography （GC）， gas chromatography-mass spectrometry （GC-MS）， molecular fluorescence spectroscopy， and Raman spectroscopy， they facilitate highly accurate and sensitive detection of these new pollutants in food products. Future directions include improving synthesis methods. Current methods are time-consuming and costly. New techniques like water-phase synthesis are promising. Multifunctional composites are needed. They should adsorb multiple pollutant types. Automated and high-throughput extraction technologies will be developed. Green and scalable production processes are essential for industrial applications. In conclusion， composite COF materials show great potential. They enhance the efficiency and accuracy of food pollutant analysis. Further research will expand their applications and improve performance.

Two-step MIL-53-PVDF membrane: (1) solvothermal synthesis of MIL-53; (2) ultrasonic dispersion into PVDF. Enables efficient SPE of trace phenoxycarboxylic acid herbicides from water.

Per- and polyfluoroalkyl substances （PFASs） are widely utilized in various industrial applications. Their persistence in ecosystems raises significant global environmental health concerns. Numerous studies have confirmed the toxicity of PFASs to human endocrine and immune systems. The carcinogenic risks associated with PFASs exposure increasingly alarm public health authorities worldwide. As a result， regulatory policies have been implemented to restrict both the production and environmental release of PFASs. In China， the GB 5749-2022 standard establishes stringent limits for PFASs concentrations in drinking water， capping levels of perfluorooctane sulfonic acid （PFOS） at 40 ng/L and perfluorooctanoic acid （PFOA） at 80 ng/L. Effective monitoring of PFASs requires advanced analytical techniques that exhibit exceptional sensitivity. Ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS） has emerged as the preferred technique for detecting these substances due to its superior selectivity and low detection limits. However， complex environmental matrices necessitate optimized sample pretreatment strategies to enhance analysis accuracy. Efficient extraction methods must effectively address matrix interference while ensuring analyte enrichment. Dispersive membrane extraction （DME） presents distinct advantages for the pretreatment of PFASs； its operational simplicity is complemented by high enrichment capabilities and efficient mass transfer. The selection of extraction materials critically influences DME performance parameters. Metal-organic frameworks （MOFs） are porous materials composed of organic ligands and metal clusters， featuring tunable pores， high surface areas， and rapid mass transfer. These unique properties enable their current use in sample pretreatment for environmental analysis. This study integrates DME with UHPLC-MS/MS utilizing cationic MOF membranes， enabling simultaneous detection of eight different PFASs within seawater matrices. Optimized parameters ensure reliable quantification of trace-level contaminants throughout this process. The experimental design assessed various parameters， including types of organic solvents （methanol and acetonitrile）， ammonium acetate concentrations in the aqueous phase （0.1， 0.5， 1.0， 2.0， and 5.0 mmol/L）， as well as ion source voltages （-2 500， -3 500， and -4 500 V）， all of which influenced detection efficacy. Chromatographic separation was performed using an ACQUITY UPLC BEH C18 column （100 mm×2.1 mm， 1.7 μm）. Gradient elution combined 1 mmol/L ammonium acetate with acetonitrile for optimal results. Detection was conducted utilizing electrospray ionization （ESI） in negative ion scanning mode coupled with multiple reaction monitoring （MRM）. The results indicated that all eight PFASs could be effectively separated within a timeframe of 12 min， exhibiting favorable peak shapes and high response values. Under optimal conditions， the eight PFASs demonstrated strong linearity across their respective concentration ranges； the correlation coefficients （r²） were all not less than 0.990 7. Recoveries of PFASs at spiking levels of 10， 50， and 100 ng/L ranged from 50.4% to 116.4%， while intra-day and inter-day relative standard deviations （RSDs） varied from 1.0% to 19.2% and from 2.2% to 19.5%， respectively. The method’s limits of detection （LODs） ranged from approximately 0.07 ng/L to 0.49 ng/L， whereas the limits of quantification （LOQs） varied from around 0.22 ng/L to 1.63 ng/L. Jiaozhou Bay serves as a typical semi-enclosed bay along the Pacific coast where terrestrial runoff converges nutrients alongside diverse organic/inorganic pollutants that pose potential health risks for aquatic organisms inhabiting these waters. This method was utilized for the detection of the eight PFASs in the surface seawater of Jiaozhou Bay， and seven types were successfully identified. Among these， potassium 11-chloroeicosafluoro-3-oxaundecane-1-sulfonate （Minor F-53B） exhibited the highest detection concentration， with an average mass concentration of 17.11 ng/L. When compared to the 2018 detection results of PFASs in the surface seawater of Jiaozhou Bay， the average mass concentration of perfluorooctanoic acid （PFOA） has significantly decreased. Additionally， potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate （F-53B）， one of the newly emerging PFASs， was detected in the surface seawater of Jiaozhou Bay， which may be attributed to the recent shift in PFASs production. The widespread use of these new PFASs may introduce environmental risks. These risks resemble those of traditional PFASs and require urgent attention. In summary， this method is operationally straightforward， rapid， and highly sensitive； it is suitable for analyzing the eight PFASs in seawater. This approach can provide a valuable data foundation and scientific basis for research and analysis concerning PFASs in environmental water bodies.

Phenoxy carboxylic acid herbicides (PCAs) are difficult to degrade and, thus, pose significant threats to the environment and human health. The limit for 2,4-dichlorophenoxyacetic acid is 30 μg/L in China’s standards for drinking water quality, 70 μg/L in the United States’ drinking water standards, and 30 μg/L in the World Health Organization’s guidelines for drinking water quality. Therefore, the development of an effective detection method for trace PCAs in water is a crucial endeavor. Metal-organic frameworks (MOFs) are novel porous materials that possess advantages such as a large specific surface area, adjustable pore size, and abundant active sites. They exhibit excellent adsorption capability for various compounds. However, the applications of MOFs as adsorbents are limited. For example, the process of isolating powdered MOFs from aqueous solutions is laborious, and microporous MOFs exhibit limited surface affinity, which decreases their mass transfer efficiency in the liquid phase. MOF crystals can be embedded in a substrate to overcome these limitations. Aerogels are obtained by drying hydrogels, which are hydrophilic polymers with a three-dimensional crosslinked network structure. Spongy aerogel materials exhibit unique structural properties such as high porosity, large pore volume, ultralow density, and easy tailorability. When MOFs are combined with an aerogel, their efficient and selective adsorption properties are preserved. In addition, MOF aerogels exhibit a hierarchical porous structure, which enhances the affinity and mass transfer efficiency of the MOF for target molecules. At present, MOF aerogels are primarily prepared by freeze-drying or using supercritical carbon dioxide. These drying processes require significant amounts of energy and time. Hence, the development of greener and more efficient methods to prepare skeleton aerogels is urgently needed. In this study, we prepared an environment-friendly aerogel at ambient temperature and pressure without the use of specialized drying equipment. This ambient-dried MOF composite aerogel was then used for the dispersive solid phase extraction (DSPE) of seven PCAs from environmental water, followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The key parameters affecting the efficiency of DSPE, including the extraction conditions, ratio of MIL-101(Fe)-NH₂ to sodium alginate, pH of the aqueous samples, extraction time, ionic strength (salinity), and elution conditions, such as the elution solvent ratio, elution time, and elution volume, were investigated to obtain optimal extraction efficiency. The adsorbent could adsorb the target contaminants within 12 min, and the analytes could be completely desorbed within 30 s by elution with 4 mL of 1.5% (v/v) formic acid in methanol solution. The water samples could be analyzed without pH adjustment. The main adsorption mechanisms were electrostatic interactions and π-π conjugation. Thus, a new method based on MOF aerogels coupled with UHPLC-MS/MS was developed for the determination of the seven PCA residues in water. The calibration curves for the seven PCAs showed good linearity (r²≥0.9986), with limits of detection (LODs) and quantification (LOQs) ranging from 0.30 to 1.52 ng/L and from 1.00 to 5.00 ng/L, respectively. Good intra- and inter-day precision values of 6.5%-17.1% and 7.4%-19.4%, respectively, were achieved under low (8 ng/L), medium (80 ng/L), and high (800 ng/L) spiking levels. The developed method was applied to the detection of PCAs in surface water, seawater, and waste leachate, and the detected mass concentrations ranged from 0.6 to 19.3 ng/L. Spiked recovery experiments were conducted at mass concentrations of 8, 80, and 800 ng/L, and the recoveries ranged from 61.7% to 120.3%. The proposed method demonstrates good sensitivity, precision, and accuracy, and has potential applications in the detection of trace PCAs in environmental water.

Dechloranes are additive-type chlorine flame retardants that are widely used in processing industrial products, such as electronic equipment and textiles. Dechloranes, which can enter the human body through various routes, pose significant health risks because of their toxicity, persistence, and bioaccumulation. In 2023, dechlorane plus was listed in the Stockholm Convention on Persistent Organic Pollutants. In the same year, China recognized this compound as a priority-controlled substance. Dechloranes are commonly found at trace levels in water, which is extremely harmful to the environment and human health. Therefore, the development of detection methods for dechloranes is crucial. Magnetic solid-phase extraction (MSPE) has attracted considerable attention because of its low organic solvent consumption, simplicity of adsorbent separation, and ease of operation. In general, the selectivity and efficiency of MSPE depend on the characteristics of the adsorbent. Covalent organic frameworks (COFs) have regular porosity, structural predictability and stability, high specific surface areas, and adjustable pore sizes, which are advantageous for a wide range of separation and analysis applications. In this study, Fe₃O₄ magnetic nanoparticles and a COF material (TpBD) were combined to prepare Fe₃O₄@TpBD as an adsorbent for dechloranes. Subsequently, an effective method for analyzing dechlorane in environmental water was established by coupling MSPE with gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The successful synthesis of Fe₃O₄@TpBD was confirmed using transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometry. A single-factor method was used to optimize the extraction conditions, including the Fe₃O₄@TpBD dosage, pH of water sample, elution solvent type and volume, extraction time, elution time, and ionic strength. The target analytes were separated on a TG-5SILMS column (30 m×0.25 mm×0.25 μm) and quantified using the external standard method in the selected-ion monitoring (SIM) mode. Under the optimal extraction conditions, the method validation results showed a linear range of 2-1000 ng/L. The limits of detection (LODs) and quantification (LOQs) were 0.18-0.27 ng/L and 0.60-0.92 ng/L, respectively, for the three analytes. The intra-day and inter-day precisions at three spiked levels were 4.2%-16.2% and 6.9%-15.7%, respectively. This method was successfully applied to the determination of dechloranes in environmental water samples (laboratory tap water, reservoir water, wastewater treatment plant effluent, and landfill leachate treatment effluent). The recoveries of the three dechloranes at different spiked levels ranged from 77.8% to 113.3% with relative standard deviations (RSDs) of 2.5%-16.3% (n=3). With the advantages of operational simplicity, high sensitivity, and good reproducibility, the proposed method is suitable for the qualitative and quantitative determination of dechloranes in environmental water.

酚类内分泌干扰物是一种干扰内分泌系统的外源性物质,其进入生物体后会干扰细胞的正常功能,引起生殖发育毒性,因此亟需开发一种快速、灵敏的分析方法,用于环境水体中酚类内分泌干扰物的检测。本研究采用溶剂热法合成了一种由金属有机骨架衍生的多孔碳材料(UiO-66-C),并将其作为萃取吸附剂来富集水中的4种酚类内分泌干扰物(双酚A、4-叔辛基苯酚、4-壬基酚、壬基酚)。建立了一种分散固相萃取(DSPE)结合超高效液相色谱-串联质谱(UPLC-MS/MS)测定水中酚类内分泌干扰物的分析方法。通过扫描电子显微镜、X射线衍射及傅里叶变换红外光谱等测试方法对UiO-66-C进行表征,证明了该材料的成功制备。对DSPE条件进行优化,包括UiO-66-C用量、水样pH、吸附时间、洗脱液种类及体积、洗脱时间和离子强度。在最佳实验条件下,4种酚类内分泌干扰物在0.5~100 μg/L范围内线性关系良好,方法检出限和定量限分别为0.01~0.13 μg/L和0.03~0.42 μg/L,日内和日间精密度分别为1.5%~10.6%和6.1%~13.2%。将该方法应用于自来水和地表水的检测,4种酚类内分泌干扰物的加标回收率为77.1%~116.6%;在自来水样品中未检测到4种酚类内分泌干扰物,而在地表水中检测到微量的4-壬基酚和壬基酚,检出水平分别为1.38 μg/L和0.26 μg/L。该方法具有良好的准确度和精密度,为环境水体中酚类内分泌干扰物的检测提供了一种快速、高效、灵敏的新途径。