Residue detection of organophosphorus pesticides is critically important. However, matrix effects in complex feed matrices often led to low purification efficiency and inaccurate recoveries when traditional adsorbents were used. To address this issue, we developed a superhydrophobic melamine sponge through in situ dopamine polymerization, followed by covalent grafting of N-propylethylenediamine silane (PSA) and dodecyl mercaptan. The resulting sponge, which offers abundant adsorption sites and selective water repellency, replaces conventional sorbents in the modified QuEChERS method. Purification was achieved by simply soaking and squeezing the sponge for one minute. The method was validated for 24 organophosphorus pesticides in feed. Excellent linearity (R2 ≥ 0.996) was obtained over the range of 0.1-2 mg/kg. Recoveries ranged from 77.61

Pectin has great application potential, but the effect of molecular weight on its physicochemical properties remains unclear. In this study, high‑molecular‑weight pectin (HMP, 425 000 Da) and low‑molecular‑weight pectin (LMP, 186 936 Da) were prepared from pomelo peel, a major food-processing by-product, by ultrasound‑assisted extraction and enzymatic depolymerization, respectively. Comprehensive characterization revealed pronounced molecular-weight-dependent differences. SEM and AFM revealed distinct morphologies, while XPS and FTIR confirmed comparable elemental composition and characteristic functional groups for both pectin fractions. The degree of methyl esterification was 83.42% for HMP and 65.0% for LMP. XRD indicated lower local chain ordering in HMP. Furthermore, LMP showed exhibited enhanced pH-responsive surface charge behavior, displaying a more negative ζ-potential in the weakly acidic to neutral pH range (5.0–7.0), together with a smaller particle size distribution (295–458 nm) compared with HMP (458–1000 nm). Whereas, HMP exhibited higher water absorbing capacity (305.8%) than LMP (253.8%). These results demonstrate that molecular weight is a critical determinant of pectin physicochemistry, governing chain organization, surface charge behavior, hydration dynamics, and functional performance, and provide a rational framework for the valorization of citrus by-products in the design of functional pectin-based biomaterials for food, pharmaceutical, and healthcare applications.

Monitoring trace nitrophenol pollutants in water has garnered considerable attention. A porous organic polymer-modified cellulose nanofiber membrane (COP-99@DCA) was fabricated via in situ growth of a porous organic polymer on an electrospun cellulose nanofiber membrane. The resulting brown COP-99@DCA composite possessed abundant functional groups, including C-F, C-O, and hydroxyl groups, and exhibited excellent thermal and chemical stability. Furthermore, when employed as a sorbent in dispersive solid-phase microextraction (d-SPME), COP-99@DCA efficiently enriched trace nitrophenols in water. Under optimal enrichment and desorption conditions, the enrichment efficiencies for five nitrophenol congeners ranged from 97.24% to 102.46%. Mechanistic investigations revealed that the efficient enrichment of trace nitrophenols by COP-99@DCA was primarily governed by hydrogen bonding, π-π stacking, and hydrophobic interactions. Coupled with solid-phase extraction (SPE) pre-treatment, high-performance liquid chromatography (HPLC) enabled the sensitive detection of trace nitrophenols. The established calibration curves exhibited favorable linearity, with low limits of quantitation (LOQs) ranging from 0.5 to 1 μg/L and low limits of detection (LODs) between 0.08 and 0.1 μg/L. Moreover, practical applications in real water samples confirmed the outstanding enrichment performance of COP-99@DCA. At spiked concentrations of 5 and 10 μg/L, the recovery rates were 85.35–113.55% and 92.17–110.46%, respectively. These results demonstrate the great potential of COP-99@DCA for practical water sample analysis. Collectively, these findings provide a novel strategy for the design of pre-treatment materials for the analysis of trace organic pollutants.

Reliable detection of pesticide residues in animal feed is essential for ensuring food safety and preventing contamination throughout the food supply chain. In this study, a novel elastic adsorbent based on reduced graphene oxide-coated melamine sponge (RGO@MeS) was developed to improve matrix cleanup for the determination of 24 organophosphorus pesticides (OPs) in complex feed samples by gas chromatography-mass spectrometry (GC-MS). This innovative material enables efficient and straightforward sample preparation via simple immersion and squeezing, substantially simplifying conventional QuEChERS workflows. The method exhibited excellent linearity (R2 >= 0.996) across a concentration range of 0.1-2 mg/kg, accompanied by minimized matrix effects that enhanced quantification accuracy. Satisfactory recoveries (74.35-126.92%) were achieved at three spiked levels (0.5, 1, and 2 mg/kg), with relative standard deviations below 15%, indicating high precision and reliability. Limits of detection (0.002-0.038 mg/kg) and quantification (0.008-0.128 mg/kg) confirmed the method's sensitivity for trace-level monitoring. Compared to conventional QuEChERS, the RGO@MeS-based approach offers superior simplicity, cost-effectiveness, and efficiency, providing an advanced sample pretreatment technique for trace-level multi-component analysis in complex matrices.

Speech-visual emotion recognition plays a vital role in human-computer interaction applications. However, it typically confronts several challenges, such as: (1) conventional speech-visual key frame (SVKF) extraction methods are susceptible to redundancy and emotional information loss; (2) widely adopted attention-based speech-visual feature fusion approaches often compute weights with limited interpretability. To address these challenges, this paper proposes an effective two-stage key frame extraction method for speech-visual emotion recognition. Specifically, in the first stage, visual key frames (VKFs) are extracted by employing information entropy (IE) to model the continuous process of emotion generation, thereby decreasing visual frame redundancy. Corresponding speech key frames (SKFs) are obtained simultaneously by eliminating silent segments to reduce redundancy in the speech modality. Subsequently, by leveraging the complementarity characteristics of speech and visual modalities, the first-stage SKFs and VKFs are aligned to produce the ultimate second-stage SVKFs for preserving important emotional information, in which a simple and interpretable weighted fusion is also proposed to focus on processing important emotional information. The experimental results on the RML, eNTERFACE05, MEAD and BAUM-1s datasets demonstrate that the proposed effective two-stage key frame extraction has better inference and generalization performance.

Perfluoroalkyl carboxylic acids (PFCAs) are a class of persistent organic pollutants (POPs), which posed various hazards to organisms, including reproductive, developmental, neurological, and immunological toxicity. Consequently, developing an analytical method aimed at achieving highly sensitive detection of trace amounts of PFCAs in complex samples is clearly of great significance. Herein, the Fluorine-functionalized covalent organic framework (F-COF) was synthesized at ambient temperature, which has the advantages of high specific surface area (1297.7 m2 g-1), suitable selective adsorption pore size and good stability. Based on the multiple effects of suitable pore size, fluorine-fluorine interactions and hydrophobic interactions, F-COF exhibited high adsorption performance towards PFCAs. Accordingly, the method of F-COF-based dispersive solid-phase extraction (dSPE) coupled with UPLC-MS/MS was developed for the quantitative analysis of 5 PFCAs in complex biological samples. The results showed that the good linearity for the 5 PFCAs within the concentration ranges of 0.4 to 104 ng L-1, with correlation coefficients (r) all greater than 0.9993. The enrichment factors (EFs) ranged from 11.4 to 22.3 folds, and the limits of detection (LODs) were 0.11 to 0.17 ng L-1. The established method provided a powerful tool for the enrichment and detection of PFCAs in mice serum and tissue. F-COF holds promising application prospects as a solid-phase extraction material for efficient enrichment separation and detection of PFCAs.

RationaleIn recent years, ephedrine psychoactive substances have attracted much attention due to their prevalence in water bodies and potential threat to aquatic ecosystems. Psychoactive substances have been considered as a new type of environmental pollutant due to their unpredictable potential risks to the behavior and nervous system of non-target organisms. A rapid, sensitive, selective, and robust method for the quantification of three ephedrine psychoactive substances in sewage is needed.MethodsAn ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of three ephedrine psychoactive substances in water. The optimal processing conditions were determined by optimizing the chromatography-mass spectrometry and solid-phase extraction (SPE) conditions (e.g., the SPE column, sample pH, washing, and elution), and the treatment conditions were determined; this was achieved via positive ion scanning in multiple reaction monitoring mode. Poly-Sery MCX was selected as the extraction column, with samples loaded at pH 3. And 4-mL solution of 2% formic acid (FA) aqueous solution was used as the eluent; the target compounds were eluted with 5 mL of 5% NH4OH in acetonitrile (ACN) solution. The best results were obtained when the residue was resolubulization in ACN after nitrogen evaporation.ResultsThe developed UPLC-MS/MS showed a good linear relationship in the range of 0-50.00 mu g/L, with determination coefficients (R2) greater than 0.9990. The detection limit and quantitation limit were 0.05-0.10 and 0.20-0.50 mu g/L, respectively. Recovery rates of the target compounds in blank sewage at three different concentrations ranged from 92.37% to 106.31%, with relative standard deviations (RSDs) of 0.77%-4.83% (n = 7).ConclusionsThis method has been successfully applied to the analysis of surface water and domestic sewage, and the samples were processed stably, indicating that the method is practical for the determination of ephedrine psychoactive drugs in water bodies.

In-tube solid phase microextraction (IT-SPME) utilizing molecularly imprinted polymers (MIPs) as extraction phase has received wide attention due to various merits. However, low extraction efficiency and unsatisfactory recognition performance have limited its extensive application. To circumvent the limitations, a new strategy that implementation of magnetic fields during extraction stage was introduced to improve the extraction efficiency and recognition performance of MIPs-based IT-SPME. Firstly, using 2,4-dinitroaniline (2,4-DNA) as model template, a MIP mingled with magnetic nanoparticles (Fe3O4) was in-situ prepared in a capillary and employed as the microextraction column of IT-SPME. In the second step, a magnetic coil was wrapped the as-prepared MIPbased microextraction column so as to produce variable magnetic fields in extraction step. Results revealed that the application of magnetic field during the adsorption step improved the specific extraction performance towards template. The extraction efficiency and imprinting factor towards 2,4-DNA increased from 58% and 2.5 to 81% and 3.1, respectively. Practicality of the introduced magnetism-assisted IT-SPME technique based on MIP was demonstrated by on-line hyphenating with HPLC/DAD to quantify trace 2,4-DNA in a variety of environmental waters. High sensitivity (limit of detection was 0.060 mu g/L), good precision (RSDs were below 10%) and satisfactory recoveries (82.1-111%) were obtained. Furthermore, the possible selective extraction mechanism under magnetic fields was deduced.

To capture fluoroquinolones (FQs) from complex samples efficiently, a new hybrid metal-organic framework (MOF)@monolith material (HMM) was fabricated and employed as the extraction medium of multi-monolith fibers solid phase microextraction (MMF-SPME). Porous monolithic fibers based on allyltrimethylammonium chloride-co-ethylene glycol dimethacrylate/divinylbenzene polymer were fabricated firstly. After that, the strategy of layer-by-layer self-assembly was employed to prepare zeolitic imidazolate frameworks within the pores and the surface of the monolith. Various characterization results well evidenced that the introduction of MOF not only enhanced the surface area of adsorbent, but also introduced new active sites. The prepared HMM/ MMF-SPME presented satisfactory capture performance towards studied FQs by multiple interactions. Enrich-ment factors of FQs in human urine and milk samples were in the ranges of 99-128 and 85-121, respectively. Under the most beneficial fabrication and extraction parameters, HMM/MMF-SPME was combined with high-performance liquid chromatography to quantify trace FQs in urine and milk samples. High sensitivity (limits of detection were 0.0072-0.031 mu g/L for urine sample and 0.016-0.057 mu g/kg for milk sample) and good pre-cision (RSDs below 10%) were obtained. In the analysis of FQs in actual samples, the recovery at different spiked contents varied from 77.4% to 120%, with good reproducibility. Accuracy and reliability of established approach were well verified with confirmation experiments. Satisfactory results evidence that the developed HMM/MMF-SPME can be a prominent technique for the capture of trace FQs in complex samples.

A new procedure that utilizing a preconcentration system based on magnetism-enhanced in-tube solid phase microextraction (ME/IT-SPME) and detection by HPLC with diode array detector (DAD) after liq-uid desorption from the microextraction column has been developed for the online measurement of tetraethyllead (TEL) in various aqueous samples. In this connection, according to the chemical features of TEL, porous monolith mingled with Fe3O4 nanoparticles were designed and synthesized in a silica cap-illary, and used as the microextraction column of ME/IT-SPME. To favor the implement of variable mag-netic fields during extraction procedure, the as-prepared microextraction column was twined a magnetic coil. Results revealed that the exertion of magnetic field during the adsorption and eluting procedures assisted the extraction of TEL with an enhancement by 52% in extraction efficiency. Under the most ben-eficial conditions, the developed ME/IT-SPME was online hyphenated with HPLC/DAD to measure trace TEL in various aqueous samples. The limit of detection was 0.082 mu g/L and the RSDs for precision were in the range of 6.3-8.5%. The recoveries with low, medium and high fortified levels varied from 80.6% to 95.0% with good repeatability. To the best of knowledge, this is the first study that using IT-SPME to extract TEL and then online quantification with HPLC/DAD.(c) 2023 Published by Elsevier B.V.

Ingesting microplastics (MPs) from plastic tableware is an important source of health risk to human bodies. However, the comprehensive information of MPs released from disposable tableware has not been explored. Herein, a new visual quantification method for polystyrene MPs is proposed with carbon nitride fluorescent polymers staining, which can overcome the disadvantages of high signal background and photobleaching derived from organic dyes staining. Combining with fluorescence microscope and ImageJ software, the quantity, shape, and size distribution of MPs carried by the brand-new disposable polystyrene tableware (DPT) samples before usage and released from the clean DPT samples in different simulated usage scenes were studied. The brand-new DPT samples were found to carry a large number of MPs particles and the clean DPT samples could release MPs during usage. Fiber and fragment are the main morphology of the detected MPs and fiber accounts for 45-52 %. The particles with size <50 μm are the majority of the detected MPs and the distribution fraction of MPs particles is gradually decreased with the raising of particle size within 50 μm. The released MPs particles are increased with the raising of contact time and temperature, and greatly boosted for the DPT samples with cracks. The DPT samples are more like to release MPs in weak acidic condition (pH 4.0) than in weak alkaline (pH 8.3) and neutral (pH 7.0) conditions. The obtained results help to assess the food safety of tack-out food and the health risk of MPs exposure to human.

Field sample preparation is important and interesting for analysis of nitrogen and sulfur containing aro-matic compounds (N,S-CACs) in environmental aqueous samples. In this connection, a new functional groups-rich adsorbent based on porous monolith (ABM) was fabricated by in-situ copolymerization of al-lylaminocarbonylphenyl boronic acid/styrene and ethylene glycol dimethacrylate. The prepared ABM was employed as the extraction medium of homemade portable multichannel in-tip microextraction device (PMMD) for on-site entrapment of N,S-CACs in various waters. Because of the abundant functional groups, the obtained ABM/PMMD exhibited satisfactory capture capability towards studied N,S-CACs, and the en-richment factors varied from 454 to 491. Under the optimized fabrication conditions, adsorption and des-orption parameters, the developed ABM/PMMD was used to field capture investigated N,S-CACs and fol-lowed by quantification with high performance liquid chromatography. The limits of detection were in the ranges of 0.0 0 030-0.0 016 mu g/L. Recoveries with low, medium and high spiked contents located in the range of 82.1-118% with good repeatability (RSDs < 9%). In addition, traditional laboratory sample pretreat-ment approach was employed to verify the reliability of the established method. Results well evidenced that the practicability of introduced ABM/PMMD in the field sample preparation of N,S-CACs in environ-mental waters. (c) 2022 Elsevier B.V. All rights reserved.

Fluorescence resonance energy transfer (FRET) is the radiation process which the donor molecules at the excited state transferred capacity to the acceptor molecules via remote dipole. Aptamers can specially recognize its target molecules. Based on these principles, a sensitive and selective fluorescent sensor for bisphenol A (BPA) has been designed. The fluorescence intensity of the sensing system increased gradually with the increasing of BPA concentration. Delta F has a linear relationship with the logarithm of BPA concentration in the range of 0.1 nM - 10 nM concentration with a correlation coefficient (R) of 0.9986 and the detection limit of 0.07 nM (defined as S/N=3). The proposed fluorescent sensor has good selectivity for BPA assay even in the presence of higher concentration of interferents.

A method based on reversed-phase liquid chromatography-tandem mass spectrometry (LC/MS/MS) coupled with solid phase extraction (SPE) was developed and validated for qualitative and quantitative detection of eight parabens in four types of food simulant sample, including distilled water, 3% acetic acid, 10% ethanol and olive oil. The detection limits of the eight parabens after the SPE procedure were in the range of 0.005-0.010 mu g L-1 in distilled water, 0.006-0.015 mu g L-1 in 3% acetic acid, 0.005-0.017 mu g L-1 in 10% ethanol and 0.2-0.6 mu g L-1 in olive oil. The relative standard deviations (RSDs) were in the range of 1.90-8.48% for distilled water, 1.01-3.73% for 3% acetic acid, 5.78-12.97% for 10% ethanol and 0.29-5.40% for olive oil. The proposed method was applied to assess the migration of parabens from real antibacterial plastic packaging samples with satisfactory results.

A novel porous monolith has been prepared and used as a sorbent in stir-cake-sorptive extraction (SCSE). The monolithic material was prepared by in-situ copolymerization of allyl thiourea (AT) and divinylbenzene (DB) in the presence of dimethylformamide as a porogen solvent. To optimize the polymerization conditions, different monoliths with different ratios of functional monomer to porogenic solvent were prepared, and their extraction efficiency was investigated in detail. The monolith was characterized by elemental analysis, scanning electron microscopy, mercury intrusion porosimetry, and infrared spectroscopy. Analysis of polar phenols in environmental water samples by a combination of ATDB-SCSE and HPLC with diode-array detection was selected as a model for the practical application of the new sorbent. Several extraction conditions, including extraction and desorption time, pH, and ionic strength of the sample matrix were optimized. The results showed that the new monolith had high affinity for polar phenols and could be used to extract them effectively. Under the optimum conditions, low detection (S/N = 3) and quantification (S/N = 10) limits were achieved for the phenols, within the ranges 0.18–0.90 and 0.59–2.97 μg L−1, respectively. The linearity of the method was good, and the method enabled simple, practical, and low-cost extraction of these analytes. The distribution coefficients between ATDB and water (K ATDB/W) were calculated for the phenolic compounds and compared with K O/W. Finally, the proposed method was successfully applied to the determination of the compounds in three environmental water samples, with acceptable recovery and satisfactory repeatability.

A simple and fast method for the simultaneous determination of two mouldy compounds, 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA), in cork by gas chromatography-mass spectrometry (GC-MS) was established. The analytes were extracted by ultrasonic extraction with methanol, and purified then by solid phase extraction using primary secondary amine (PSA) as solid phase. After concentrating, the sample was analyzed by GC-MS and quantified by the external standard method. The linear ranges were from 10 microg/L to 10 000 microg/L for TCA and TBA, the correlation coefficients (r2) of the calibration curves were above 0.99. The recoveries and the relative standard deviations (RSDs) of TCA and TBA in different kinds of corks were investigated. The recoveries ranged from 88.4% to 97.6% with the RSDs between 1.02% and 4.58% (n = 6). The limits of detection (LODs) were 12 microg/L for TCA and 18 microg/L for TBA, and the limits of quantification (LOQs) were 40 microg/L for TCA and 50 microg/L for TBA. The method is suitable to the determination of TCA and TBA in corks.

An electrochemiluminescent (ECL) method has been developed for the determination of melamine based on the inhibition of luminol ECL. A significant luminol ECL can be found at 1.47 V in the phosphate buffer solution at high pHs and low potential scan rates, this ECL signal can be inhibited obviously by melamine. The decrease of ECL intensity was linearly proportional to the logarithm of melamine concentration in the range of 1–100 ng/mL ( R 2 =0.9911) and with the detection limit of 0.1 ng/mL. The method has been applied successfully to determine melamine in dairy products and melamine tableware, the recoveries were in the range of 98.5%–103.7% and 95.5%–106.0%, respectively. The mechanism of the inhibition effect was also proposed, the active oxygen (O 2 · − ) generated from the electrooxidation of OH − reacted with luminol anion (L · − ) to generate light emission, and the present of melamine can eliminate the active oxygen, which cause the decrease of the ECL intensity.

A high-throughput, rapid and sensitive method of using ZIC-HILIC was developed for simultaneously qualitative and quantitative determination of melamine and triazine-related by-products including ammelide, ammeline, and cyanuric acid in food contact material. Linear responses were observed for samples ranging from 0.1 - 200 ppb for melamine, ammelide, ammeline, and cyanuric acid with a correlation coefficient no less than 0.999. The method for simultaneous determination of melamine, ammelide, ammeline, and cyanuric acid in food contact material is sensitive and specific. © 2011 IEEE.

N-Acylated homoserine lactones (AHLs) are produced by Gram-negative bacteria as communication signals and are frequently studied as mediators of the “quorum sensing” response of bacterial communities. Several reports have recently been published on the identification of AHLs from different species and attempts have been made to study their role in natural habitats, for example the surface of plant roots in the rhizosphere. In this article, different analytical methods, including bacterial biosensors and chromatographic techniques, are reviewed. A concept for assignment of the structures of AHLs is also presented. The retention behaviour of derivatives of AHLs containing β-keto or hydroxyl groups and/or double bonds has been evaluated in relation to the separation behaviour of AHLs with saturated and unsubstituted alkanoyl chains. Samples have also been analysed by high resolution mass spectrometry (Fourier-transform ion-cyclotron-resonance mass spectrometry, FTICR-MS), nano liquid chromatography–electrospray ionization ion trap mass spectrometry (nano-LC–MS) and by the aid of a biosensor. The results obtained from ultra performance liquid chromatography (UPLC), FTICR-MS, nano-LC–MS, and bioassays have been compared to attempt structural characterisation of AHL without chemical synthesis of analytical standards. The method was used to identify the major AHL compound produced by the rhizosphere bacterium Acidovorax sp. N35 as N-(3-hydroxydecanoyl)homoserine lactone.