Complex Food Samples Research Articles

New Materials for Thin-Film Solid-Phase Microextraction (TF-SPME) and Their Use for Isolation and Preconcentration of Selected Compounds from Aqueous, Biological and Food Matrices.

Determination of a broad spectrum of analytes, carried out with analytical instruments in samples with complex matrices, including environmental, biological, and food samples, involves the development of new and selective sorption phases used in microextraction techniques that allow their isolation from the matrix. SPME solid-phase microextraction is compatible with green analytical chemistry among the sample preparation techniques, as it reduces the use of toxic organic solvents to the minimum necessary. Over the past two decades, it has undergone impressive progress, resulting in the development of the thin-film solid-phase microextraction technique, TF-SPME (the thin-film solid-phase microextraction), which is characterized by a much larger surface area of the sorption phase compared to that of the SPME fiber. TF-SPME devices, in the form of a mostly rectangular metal or polymer substrate onto which a thin film of sorption phase is applied, are characterized, among others, by a higher sorption capacity. In comparison with microextraction carried out on SPME fiber, they enable faster microextraction of analytes. The active phase on which analyte sorption occurs can be applied to the substrate through techniques such as dip coating, spin coating, electrospinning, rod coating, and spray coating. The dynamic development of materials chemistry makes it possible to use increasingly advanced materials as selective sorption phases in the TF-SPME technique: polymers, conducting polymers, molecularly imprinted polymers, organometallic frameworks, carbon nanomaterials, aptamers, polymeric ionic liquids, and deep eutectic solvents. Therefore, TF-SPME has been successfully used to prepare analytical samples to determine a broad spectrum of analytes in sample matrices: environmental, biological, and food. The work will be a review of the above-mentioned issues.

Aptamer-Conjugated Covalent-Organic Framework Nanochannels for Selective and Sensitive Detection of Aflatoxin B1.

Sensitive and selective detection of trace aflatoxin B1 (AFB1) in foods is of great importance to guarantee food safety and quality but still challenging because of its trace amount and the interference from the complex food matrix. Here, we report the integration of aptamer (Apt) and an ordered 2D covalent organic framework (COF) to solid-state anodic aluminum oxide (AAO) nanochannels (Apt/COF/AAO) for selective and sensitive detection of trace AFB1. The high specificity of Apt for AFB1 led to a selective change in the surface charge of Apt/COF/AAO and in turn the current change of the nanochannel, permitting the selective and sensitive determination of trace AFB1 in complex food samples. The developed nanofluidic sensor gave a wide linear range (1-500 pg mL-1), low detection limit (0.11 pg mL-1), and good precision (relative standard deviation of 1.5% for 11 replicate determinations of 100 pg mL-1). In addition, the developed sensor was successfully used for the detection of AFB1 in food samples with the recovery of 86.9%-102.5%. The coupling of Apt-conjugated 2D COF with an AAO nanochannel provides a promising way for sensitive and selective determination of food contaminants in complex samples.

A novel fluorescent probe for formaldehyde based on hydrazone formation for real food samples detection and bioimaging

Formaldehyde (FA) is an active carbonyl structure that is widely used in people's daily life, such as preservatives and fixatives. Furthermore, formaldehyde is highly toxic and has been listed as one of the three major indoor pollutants. Therefore, the development of highly sensitive and selective fluorescent probes is of great biological importance. In this article, probe X is designed to identify formaldehyde by a light-induced electron transfer (PET) process between the naphthalimide derivative and the hydrazine group based on hydrazone formation. Moreover, the probe has good optical response and excellent linearity over a wide range of formaldehyde concentrations, ensuring that formaldehyde concentration values in real complex food samples can be quantitatively recorded. In addition, the probe can monitor the changes of formaldehyde levels in living cells with good biocompatibility and image resolution.

IR spectra simulations by anharmonic DFT and CDFT-saturated and unsaturated fatty acids of Siberian sturgeon (Acipenser baerii Brandt,1869)

The Siberian sturgeon is one of the most remarkable species in the field of aquatic biology which also has ecological importance, commercial significance, and nutritional characteristics. The purpose of this study is to determine the fatty acid content of different organs of Siberian sturgeon through both theoretical and experimental techniques to compare oxidative stability of the samples in terms of fatty acid profile. For this purpose, the fatty acid content of flesh, brain, caviar and liver of sturgeon was determined by gas chromatography and the middle infrared spectra of tissues were collected by an infrared spectrofotometer. The fatty acid content of samples was also computed by anharmonic DFT and CDFT calculations using IR spectra. Oleic acid was the most abundant fatty acid in all tissues. All tissues accumulated by docosahexanoic, eicosapentanoic and linolenic acids. The PCA model was able to classified the tissues with respect to fatty acid contents. Comprehensive anharmonic DFT calculations were performed to better understand the fatty acid of samples at the atomistic level and to predict the spectra of more complex food samples with varying fatty acid compositions. Oxidative stabilities of fatty acids were also investigated through Conceptual DFT based computations. Maximum Hardness and Minimum Electrophilicity Principles accurately predicted saturated and unsaturated fatty acids of sturgeon as the experimental data revealed.

Polymer inclusion membrane for the extraction of oxytetracycline from milk prior to aptamer-based biosensing

Aptamer-based sensing may suffer from severe limitations when applied to complex biological and food samples. To alleviate the interference of matrix elements, we propose the use of a polymer inclusion membrane (PIM) as a simple, yet effective sample clean-up tool prior to aptamer-based sensing. As a proof-of-concept, Aliquat 336 anion exchanger was incorporated into a plasticized cellulose acetate membrane to transport oxytetracycline (OTC) from raw milk into an aqueous NaCl acceptor solution. Efficient transport has been ensured by adding a chelating agent to the raw milk and adjusting the pH to alkaline. The amount of extracted OTC was determined as a function of time and acceptor phase NaCl concentration. The extracted amount was proportional to the raw milk OTC concentration in the investigated 0.22–2.2 µM range. Circular dichroism spectroscopy was used to examine the conformation of an OTC-binding aptamer to evaluate if PIM extracts are compatible with aptamer-based biosensors. Solid phase extraction (SPE) was used as a reference sample pre-treatment technique. The aptamer retained its native conformation in the PIM extract, contrary to the SPE extract, and responded to the presence of OTC. Consequently, the PIM-based extraction is adaptable to aptasensor constructs. Besides its simplicity, it offers a cheaper and greener alternative to other sample preparation procedures.

Thylakoid-based green preparation of porous microneedles for antibiotic residues detection in food samples

BackgroundAntibiotic residues in food chain have raised concerns regarding their toxicity and involvement in antimicrobial resistance. However, most existing antibiotic biosensors are primarily applicable to liquid food samples. Given the complex matrix characteristics of foods, there is an urgent need for the development of effective antibiotic detection platforms that exhibit high universality and flexibility. Porous microneedles (PMN) are microdevice structures with needle-like shapes and microscale pores throughout their composition, which facilitate rapid sampling. Consequently, the integration of PMN with biosensors holds significant promise for the detection of antibiotic residues in complex food samples. ResultsIn this study, hydrogel-forming PMN are fabricated by leveraging the oxygen-production capacity of thylakoid to generate bubbles and form porous structures. These PMN are then integrated with a fluorescence aptasensor for the quantification of the antibiotic netilmicin. The aptasensor consists of a netilmicin (NET) aptamer with stem loop and hairpin structure, which facilitated the binding of SYBR Green I to produce a fluorescent signal. In the presence of NET, the complete binding between NET and the aptamer results in a reduction of fluorescence intensity, thereby generating a detectable signal change for the detection of NET. Utilizing capillary action accelerate fluid extraction (2.9 times faster than nonporous microneedles) and a large specific surface area (5.1072 m2/g) conducive to aptasensor adsorb, the PMN achieve efficient capture and quantification of antibiotic with limits of detection and quantitation of 5.99 nM and 19.8 nM, respectively. SignificancePorous microneedles with tunable porosity and desirable mechanical properties are successfully fabricated. The integration of PMN with aptasensor enable the efficient detection of netilmicin in fish, milk and river water samples, demonstrating high recovery rates. The PMN represent potential tools for the convenient and rapid detection of antibiotic residues within complex food matrices, thereby enhancing food safety monitoring.

Click chemistry-mediated stable isotope labeling combined with HPLC-MS/MS analysis for highly sensitive determination of steroid hormones

Steroid hormone residues in food are a significant sources of endocrine disrupting chemicals (EDCs) that can adversely affect public health. However, the current analytical methods for determining steroid hormones using liquid chromatography-tandem mass spectrometry (LC-MS/MS) can be challenging due to the poor ionization efficiency of steroid hormones and the matrix effect of complex food samples. Herein, based on Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and stable isotope labeling (SIL) technique, a novel pair of chemoselective probes ABI/d5-ABI was precisely designed and synthesized. This pair of probes comprises a H/D isotope tag, a linker, a reactive site azido group (N3) and a MS tag (imidazolium salt). The probe ABI was employed to label ethynyl-containing steroid hormones in real samples and d5-ABI was applied to label standards, respectively, followed by mixing the two labeled samples for high performance (HP)LC-MS/MS analysis. It was found that the ionization efficiencies of target analytes were increased by 17–4532 folds after ABI labeling. More importantly, the heavy labeled samples serving as internal standards (ISs) can effectively compensate matrix effect during HPLC-MS/MS analysis. Finally, the proposed SIL-HPLC-MS/MS method was successfully used to highly sensitive determine four synthetic steroid hormones in food samples (milk, pork and egg). Furthermore, the good detection limits (0.015–0.020 ng/mL), satisfactory recoveries (75.7–122.9 %), and precisions (RSDs less than 9.2 %) were obtained. Hence, the established method not only provides new insights in designing SIL probes for determination of ethynyl-containing analytes within complex matrix, but also extends the application of CuAAC reaction in the field of food chemistry.

Nanozyme-catalyzed and zwitterion-modified swabs based for the detection of Listeria monocytogenes in complex matrices

In recent years, nanozymes have been widely used in the field of biosensing and food safety testing due to their advantages of low cost, high stability, easy modification and adjustable catalytic activity. However, how to reduce the signal interference generated by reducing substances, macromolecules and colored substances in the food matrix in nanozymes-based colorimetric sensing is still a major challenge. In this paper, using Listeria monocytogenes as a model analyte, sodium sulfonyl methacrylate (SBMA) polymers were modified onto cotton swabs by photothermal polymerization and combined with Listeria monocytogenes-specific aptamer (Apt1) to prepare swabs that can specifically capture and isolate Listeria monocytogenes from complex matrices (SBMA/Apt1 cotton swab). In addition, in combination with the inhibitory effect of the aptamer (Apt2) on the oxidase activity of Mn3O4 NPs, a colorimetric biosensor based on nanozymes that can quantitatively, sensitively, and specifically identify Listeria monocytogenes in food products was constructed. The results showed that the colorimetric signal of the method was linear with the concentration of Listeria monocytogenes in the range of 2.83–2.83 × 105 CFU/mL, and the limit of detection was 2.64 CFU/mL, which can be used for the detection of Listeria monocytogenes in complex environments and food samples.

Self-assembled Fe3O4–COOH @ hydrogen-bonded organic framework composites for magnetic solid-phase extraction of tetracycline in food samples coupled with HPLC determination

Magnetic solid-phase extraction (MSPE) technology for tetracycline (TCC) was developed by employing the novel and pre-designed Fe3O4–COOH@hydrogen-bonded organic frameworks (HOFs) adsorbents in complex food samples. The HOF shell was grown onto the Fe3O4–COOH core by in-situ self-assembled method. The excellent MSPE performances with less solvent, less adsorbent and time consumption were derived from the hydrogen bonding, π-π and hydrophobic interactions between HOF shell and TCC. Combined with HPLC analysis, Fe3O4@ HOFs adsorbent reduced matrix effects and the established MSPE-HPLC method for TCC gave the linearity of 0.001–6 μg mL−1 with the limit of detection 0.0003 μg mL−1. The recoveries in pure milk, canned yellow peach and carrot were 82.4–103.7 %. The method provided a simple, efficient and dependable alternative to monitor trace TCC antibiotics in food or environmental samples.

Hydrophilic molecularly imprinted thermal-responsive polymers based sorbent for ambient ionization mass spectrometric analysis of sulfonamide antibiotics from food samples

The thermal-responsive magnetic molecularly imprinted polymer (TrMMIP) sorbent was synthesized by surface imprinting method, and then used for magnetic solid-phase extraction (MSPE) and subsequent integrated into the ion source for elution and ionization. The shrinking-strength states change of the thermal-responsive polymer chain on TrMMIP alters the wettability of the sorbent when the working temperature crosses the lower critical solution temperature (LCST) of the polymer, and thus affects its behavior of in the extraction and clean-up process. The targeted analytes could be effectively extracted due to the high selectivity of MIPs and well dispersibility of polymer chain under the open state. Additionally, a hydrophilic polymer chain wrapped on the sorbent surface further protected target substances from co-elution during cleanup. Analytical methods for sulfonamide antibiotics (SAs) detection in complex food samples (milk, honey, fish) were developed, demonstrating potential for rapid and sensitive SAs analysis in diverse food and biological samples.

Molecularly imprinted polymer based on covalent organic framework coated steel substrate as the mass spectrometric ionization source for the direct detect of aflatoxins in complex food matrices

Ambient mass spectrometry allows direct analysis of various sample types with minimal or no pretreatment. However, due to the influence of matrix effects, there are sensitivity and issues in analyzing trace analytes in complex food samples. In this work, we developed a spray mass spectrometry platform based on SSS@TPBD-TPA@MIPs (Stainless steel substrate (SSS), terephthalaldehyde (TPA), N, N, N′, N′-tetrakis(p-aminophenyl)-p-phenylenediamine (TPBD), molecularly imprinted polymer (MIP)), for rapid, in situ, high-throughput, highly enrichment efficiency and highly selective trace analysis of aflatoxins. By simplifying the sample pretreatment and directly applying high voltage for ESI-MS, the analysis can be completed within 1 min. The established method base on SSS@TPBD-TPA@MIPs exhibited high sensitivity and accuracy when determine trace level AFs in maize and peanuts. The results demonstrated a good linear relationship within the range of 0.01–10 μg/L, with the determination coefficient (R2) ≥ 0.9956. The limits of detection (LODs) was 0.035–0.3 ng/mL and limits of quantitation (LOQs) was 0.12–0.99 ng/mL, with acceptable recovery rate of 82.09–115.66 % and good repeatability represented by the relative standard deviation (RSD) less than 17.43 %. Furthermore, SSS@TPBD-TPA@MIPs exhibited excellent reusability, with more than 8 repeated uses, and showed good adsorption performance.

A novel biomass carbon dots ratiometric fluorescence probe coupled with molecularly imprinted polymer for selective detection of aflatoxin B1

The accumulation of Aflatoxin B1 (AFB1) in food and crops can pose significant hazards to human health. Consequently, there has been extensive attention paid to the development of a rapid and reliable method for detecting AFB1 in food. In this context, a ratiometric fluorescence probe (DE-MIPs) was prepared using dual-emission fluorescent carbon dots (CDs) coupled with the molecular imprinting technique for visual detection of AFB1. The dual-emission CDs consisted of red fluorescence biomass CDs (R-CDs) wrapped by molecularly imprinted cavities (R-CDs@MIPs), which served as a response signal, and pure blue emission biomass CDs (B-CDs) as a reference signal. Due to the specific quenching effect of AFB1 on red fluorescence while leaving blue fluorescence unaffected, there was a gradual decrease in the fluorescence intensity ratio (I670/I437) and a distinct shift in fluorescence color from red to blue as the concentration of AFB1 increased. The ratiometric probe demonstrated excellent linearity in detecting AFB1 within the concentration range of 0.1–200 ng/mL, with a detection limit (LOD) of 0.05 ng/mL. Furthermore, the practicality of DE-MIPs was validated by successfully detecting AFB1 in vegetable oil, with desirable recoveries from 89.0% to 107.4%. Furthermore, the integration of a smartphone as colorimetric reader enabled rapid AFB1 detection by capturing changes in fluorescence color. Overall, the development of this ratiometric probe offers a novel perspective for the facile and efficient identification of AFB1 in complex food samples.

Cu2(OH)3NO3 nanozyme sensor array for the discrimination of multiple sulfides in food

In the food industry, sulfides are commonly used as preservatives and flavor regulators. However, long-term excessive intake of sulfides can lead to serious health problems. Therefore, developing efficient sulfide detection methods is particularly important. Here, we have effectively synthesized a novel bifunctional copper hydroxide nitrate (Cu2(OH)3NO3) nanozyme with outstanding peroxidase-like and laccase-like behaviors in basic deep eutectic solvents (DES). Because the various types of sulfides have diverse regulatory effects on the two catalytic behaviors of Cu2(OH)3NO3, a two channel nanozyme sensor array based on the peroxidase-like and laccase-like behaviors of Cu2(OH)3NO3 was constructed and successfully used for the identification of six kinds of sulfides (Na2S, Na2S2O3, Na2SO3, Na2SO4, NaHSO3, and Na2S2O8). Remarkably, the sensor array has achieved successful discrimination among six sulfides present in wine, egg, and milk samples. Finally, the sensor array has successfully distinguished and differentiated three actual samples (wine, egg, and milk). This study is of great significance in promoting the efficient construction of array units and improving the effective identification of sulfides in complex food samples.

A rapid near-infrared turn on fluorescence probe for the detection of sulfite in food and its application in biological imaging

A near-infrared fluorescent “turn on” probe DTMI featuring simple skeleton was constructed easily. It undergoes a structure transformation from an A−π−A to a D−π−A framework towards SO32−. Besides, DTMI is capable of distinctive sensing sulfite with a fast response and a significant Stokes shift as well as with high sensitivity, excellent selectivity, long-term stability of fluorescence signals, and good anti-interference ability. The detection limit (LOD) of DTMI for sulfite within the linear concentration range of 0.5–10 μM is 27.39 nM. More importantly, DTMI has been favorably utilized for detecting sulfite in food samples such as red wine and vermicelli. Based on its low biotoxicity, DTMI has been successfully applied in imaging experiments involving HeLa cells, onion inner epidermal cells, and zebrafish. Therefore, the results show that the presented probe possesses potential sensing activity towards sulfite in complex biological system and food samples.

A ratiometric fluorescent probe for cysteine and glutathione differentiation and its application for cysteine detection in foods

Cysteine (Cys) and glutathione (GSH) are crucial biothiols implicated in cellular redox balance, necessitating accurate detection methods. Herein, we developed a novel fluorescent probe based on the fluorescent dye pyronin (PYR), capable of monitoring both Cys-and GSH using ratiometric fluorescence signals. The probe, named PYR-CG, where "C" stands for Cys-and "G" stands for GSH, demonstrates selective detection capabilities for Cys-and GSH. UV absorption and fluorescence emission spectra changes revealed distinct shifts upon interaction with Cys-and GSH. Theoretical and experimental studies validated PYR-CG's responsiveness to Cys-and GSH, elucidating its mechanism as a ratiometric probe. Notably, PYR-CG exhibited rapid response kinetics for Cys-and GSH, with low detection limits of 88 nM and 164 nM, respectively. Importantly, PYR-CG demonstrated exceptional selectivity for Cys-and GSH over interfering analytes. Screening of molecules with similar structures to Cys-further affirmed PYR-CG's specificity, particularly towards N-terminal Cys-in peptides. Furthermore, recovery experiments underscored PYR-CG's reliability for quantitative Cys-detection in complex food samples. Our findings highlight the innovative design and practical applicability of PYR-CG, offering a valuable tool for sensitive and selective detection of Cys-in diverse biological and food samples.

Highly sensitive detection of fluorescent whitening agents in flour using sheathless capillary electrophoresis-electrospray ionization-tandem mass spectrometry

Fluorescent whitening agents (FWAs) are dyes that emit visible blue or blue-purple fluorescence upon ultraviolet-light absorption. Taking advantage of light complementarity, FWAs can compensate for the yellow color of many substances to achieve a whitening effect; thus, they are used extensively in various applications. FWAs are generally stable, but their presence in the environment can lead to pollution and accumulation in the body through the food chain. Recent studies have revealed that some types of FWAs, such as coumarin-based FWAs, may exhibit photo-induced mutagenic effects that can trigger allergic reactions in humans and even pose carcinogenic risks. Hence, the development of an accurate and highly sensitive method for detecting FWAs in food-related samples is a crucial endeavor. Owing to the high polarity and structural similarity of FWAs, the accurate determination of these substances in complex food samples requires an analytical method that offers both efficient separation and sensitive detection. Capillary electrophoresis (CE) exhibits essential features such as high separation efficiency, short analysis times, very small sample injection requirements, minimal use of organic solvents, and simple operation. Thus, it is often used as an effective alternative to liquid chromatographic techniques. Over the past few decades, electrospray ionization mass spectrometry (ESI-MS) has been utilized as a highly sensitive and accurate detection method in numerous chemical analytical fields because it enables the analysis of molecular structures. By combining the high separation efficiency of CE with the high sensitivity of ESI-MS, a powerful tool for identifying and quantifying trace amounts of FWAs in food samples may be obtained. In this study, we present a method based on sheathless CE coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS) for the simultaneous detection of six trace FWAs in flour. In the proposed method, the CE separation device is directly coupled to the mass spectrometer through a sheathless interface without the need for a sheath liquid for electric contact, thereby avoiding the dilution of the analytes and improving detection sensitivity. Various conditions that could affect extraction recovery, separation efficiency, and detection sensitivity were evaluated and optimized. The FWAs were effectively extracted from the sample matrix with reduced matrix effects by ultrasonic-assisted extraction at a temperature of 30 ℃ for 20 min using CHCl3-MeOH (3∶2, v/v) as the extraction solvent. The extract was centrifuged, dried under N2, and reconstituted in CHCl3-MeOH (1∶4, v/v) for subsequent analysis. During the detection process, the CE device was coupled to the ESI-MS/MS instrument via a highly sensitive porous spray needle, which served as the sheathless electrospray interface. The target FWAs were scanned in positive-ion mode (ESI+) to ensure the stability and intensity of the obtained signals. Additionally, multiple-reaction monitoring (MRM) mode and MS/MS analysis were used to simultaneously quantify the six targets with high selectivity. The developed sheathless CE-ESI-MS/MS method detected the FWAs with high sensitivity over wide linear ranges with low method limits of detection (0.04-0.67 ng/g). The recoveries of the six target FWAs at three spiked levels were between 77.5% and 97.2%, with good interday (RSD≤11.5%) and intraday (RSD≤10.2%) precision. Analyses of the six target FWAs in eight commercial flour samples were performed using this method, and four positive samples were identified. These results demonstrate that the proposed CE-ESI-MS/MS method is a promising strategy for the determination of trace FWAs in complex food sample matrices with efficient separation and high sensitivity.

Synthesis of a molecularly imprinted polymer-based thin film as a smart sorbent for microextraction by packed syringe of n-propyl gallate in vegetable edible oils followed by its colorimetric detection applying a smartphone

In the current work, a molecularly imprinted polymer (MIP) as a smart sorbent was prepared for the selective recognition of n-propyl gallate (n-PG) in complex food samples. A computational study was used to design a selective and efficient MIP toward n-PG. MIP has been synthesized on the cellulose substrate and used as a smart sorbent in microextraction by the packed sorbent (MEPS) method. Digital image colorimetry (DIC) was utilized to assay the generated color on the thin film platform. Based on the method validation, the linear dynamic range was 0.1–1 µg mL−1 and 1–10 µg mL−1 for natural sesame oil. The limit of detection and limit of quantification for natural sesame oil were 0.03 and 0.1 µg mL−1, respectively. The developed MIP-MEPS combined with DIC assay was successfully applied to determine of n-PG in some vegetable edible oils, leading to acceptable relative recoveries in the range of 83.0 % to 108.6 %.

Dual-ligand lanthanide metal-organic framework based ratiometric fluorescent platform for visual monitoring of aminoglycoside residues in food samples

Herein, a dual-emission Eu metal-organic framework (Eu-MOF) is prepared and used as the ratiometric fluorescence probe for ultrasensitive detection of aminoglycoside antibiotics (AGs). Due to the strong hydrogen bond interactions between AGs and Eu-MOF, the blue emission is enhanced while the red emission has little fluctuation in Eu-MOF with the addition of AGs, thus a good linear relationship with the logarithm of AGs concentrations from 0.001 to 100 μg/mL can be established for quantitative analysis. Good sensitivity with the detection limit of 0.33 ng/mL for apramycin, 0.32 ng/mL for amikacin and 0.30 ng/mL for kanamycin is achieved. The proposed assay demonstrates good selectivity and applicability for determination of AGs in real milk and honey samples. The Eu-MOF materials are further fabricated as fluorescent test papers for facile visual detection. The as-established ratio fluorescence platform offers a portable and economical way for rapid monitoring AGs residues in complex food samples.

Highly Sensitive Electrochemical Determination of Butylated Hydroxyanisole in Food Samples Using Electrochemical-Pretreated Three-Dimensional Graphene Electrode Modified with Silica Nanochannel Film.

The sensitive detection of antioxidants in food is essential for the rational control of their usage and reducing potential health risks. A simple three-dimensional (3D) electrode integrated with an anti-fouling/anti-interference layer possesses great potential for the direct and sensitive electrochemical detection of antioxidants in food samples. In this work, a 3D electrochemical sensor was developed by integrating a 3D graphene electrode (3DG) with vertically ordered mesoporous silica film (VMSF), enabling highly sensitive detection of the common antioxidant, butylated hydroxyanisole (BHA), in food samples. A simple electrochemical polarization was employed to pre-activate the 3DG electrode (p3DG), enhancing its hydrophilicity. Using the p3DG as the supporting electrode, stable modification of VMSF was achieved using the electrochemical assisted self-assembly (EASA) method, without the need for any adhesive agents (VMSF/p3DG). Taking BHA in food as a model analyte, the VMSF/p3DG sensor demonstrated high sensitivity, due to the enrichment by nanochannels, towards BHA. Electrochemical detection of BHA was achieved with a linear range of 0.1 μM to 5 μM and from 5 μM to 150 μM with a low limit of detection (12 nM). Owing to the fouling resistance and anti-interference capabilities of VMSF, the constructed 3D electrochemical sensor can be directly applied for the electrochemical detection of BHA in complex food samples.

Sacrificial template synthesis of hollow sulfonate group functionalized microporous organic network for efficient solid phase extraction of sulfonamide antibiotics from milk and honey samples

The highly conjugated and hydrophobic characteristics of microporous organic networks (MONs) have largely impeded their broad applications in sample pretreatment especially for the polar or ionic analytes. In this work, a novel uniform hollow shaped sulfonate group functionalized MON (H-MON-SO3H-2) was synthesized via the sacrificial template method for the efficient solid phase extraction (SPE) of sulfonamides (SAs) from environmental water, milk, and honey samples prior to HPLC analysis. H-MON-SO3H-2 exhibited large specific surface area, penetrable space, good stability, and numerous hydrogen bonding, electrostatic, hydrophobic and π-π interaction sites, allowing sensitive SPE of SAs with wide linear range (0.150-1000 μg L−1), low limit of detection (0.045-0.188 μg L−1), good precisions (intra-day and inter-day RSD < 7.3%, n = 5), large enrichment factors (95.7-98.5), high adsorption capacities (250.4-545.0 mg g−1), and satisfactory reusability (more than 80 times). Moreover, the established method was successfully applied to extract SAs from spiked samples with the recoveries of 86.1-104.3%. This work demonstrated the great potential of H-MON-SO3H-2 in the efficient SPE of trace SAs in complex environmental water and food samples and revealed the prospect of hollow MONs in sample pretreatment.