Residues In Food Samples Research Articles

A novel electrochemical sensor (Au-Ag-ANCCs/r-GO/poly(L-histidine)/GCE) for the simultaneous determination of vancomycin and ceftriaxone residues in chicken meat, fish, and milk samples

The widespread use of antibiotics in humans and animals has resulted in the accumulation of their residues in food and the environment, posing significant threats to human health, the environment, and the global economy. Herein, we have developed a highly sensitive and selective electrochemical sensor by integrating gold-silver alloy nanocoral clusters (Au-Ag-ANCCs) with reduced graphene oxide (r-GO) and poly(L-histidine) composites at the surface of glassy carbon electrode (GCE). The developed sensor (Au-Ag-ANCCs/r-GO/poly(L-histidine)/GCE) was designed for the simultaneous determination of vancomycin (VAN) and ceftriaxone (CFT) residues in food samples. Its morphological and electrochemical properties were exhaustively examined using UV–Vis spectroscopy, FT-IR, XRD, SEM, EDX, EIS, and CV. The sensor showed exceptional performance in a linear range of 1.0 pM to 120 μM for VAN and 1.0 pM to 290 μM for CFT. The limits of detection were 0.11 pM for VAN and 0.017 pM for CFT, while the limits of quantification were 0.36 pM for VAN and 0.057 pM for CFT. The sensor exhibited remarkable reproducibility, repeatability, stability, and selectivity. It was successfully applied to detect VAN and CFT residues in chicken meat, fish, and milk, achieving recoveries of 96.2–102.1 % with relative standard deviation (RSD) below 5 %. Therefore, the sensor is an ideal tool for addressing the global antibiotic residue crisis in food samples.

Electrospun nanofibers functionalized with metal–organic frameworks/graphene oxide for enrichment of trace-level pesticide residues in food samples

Electrospun nanofibers functionalized with metal–organic frameworks/graphene oxide for enrichment of trace-level pesticide residues in food samples

Integration of miniaturized sample preparation and molecularly imprinted polymers in food analysis

The use of innumerable chemical compounds in food production to enhance agricultural quality and yield has raised significant global concerns regarding food safety. To address these concerns, miniaturized solid sample preparation techniques have emerged as an appealing strategy for analyzing chemical residues in complex samples, notably those found in food matrices. The efficacy of these miniaturized solid extraction procedures hinges largely on the choice of the sorbent phase. Molecularly imprinted polymers (MIPs) have been introduced as highly selective and versatile sorbent phases for a wide range of miniaturized solid techniques. Their remarkable selectivity is attributed to the creation of distinct cavities during the synthesis process, which subsequently accommodate the target analyte when the sample is applied. This unique characteristic empowers MIP polymers to exhibit exceptional specificity toward the desired analyte. The use of MIPs as sorbent phases in miniaturized sample preparation methods has shown great potential to increase the analytical performance of residue evaluation in food matrices. Therefore, here we present a comprehensive overview of the current landscape of miniaturized solid sample techniques employing MIPs as sorbent phases for the assessment of residues in food samples. Moreover, this review is primarily on recent reports concerning the application of MIPs in solid-phase microextraction (SPME), in-tube SPME, microextraction by packed sorbent (MEPS), disposable pipette extraction (DPX), solid-phase extraction in pipette tip (SPE-PT) and stir bar sorptive extraction (SBSE). Lastly, we will bring some future topics concerning the use of MIPs in miniaturized sample preparation methods for food analysis in order to bring some new avenues for enhancing food products' safety and quality assessment.

Emerging Technologies for Sensitive Detection of Organophosphate Pesticides: A Review

Abstract: The use of organophosphate pesticides (OPPs) in agricultural practices improves crop yield and controls pests, but their indiscriminate use and persistence in the environment pose significant health risks. Therefore, it has become increasingly important to develop reliable and efficient detection methods for OPPs to ensure food safety and monitor their presence. In recent years, OPP detection methods have undergone significant advancements. Sensors such as colorimetric, fluorescence, electrochemical, and impedometric offer several advantages over traditional methods, such as high sensitivity, selectivity, and portability. The purpose of this review paper is to provide an overview of recent developments in OPP detection methods. The paper discusses the different types of sensors that are available for the detection of OPPs, as well as their advantages and disadvantages. Many electrochemical methods have been employed to investigate OPP detection, including voltammetry, impedance spectroscopy, and amperometry. The integration of nanomaterials, such as carbon nanotubes, graphene, and metal nanoparticles, has significantly enhanced the performance of electrochemical sensors by providing high surface area, enhanced electron transfer, and specific analyte interactions. Furthermore, the review discusses the utilization of biomolecules, such as enzymes and aptamers, as recognition elements in sensor platforms for selective and sensitive OPP detection. The incorporation of these biomolecules offers high specificity and enables real-time monitoring of OPP residues in food samples and environmental matrices. It emphasizes the importance of continued research and development to optimize detection methods, improve sensor performance, and make these technologies more widely accessible for effective monitoring and control of OPP contamination in various domains.

Hypersensitive electrochemical sensor based on thermally annealed gold–silver alloy nanoporous matrices for the simultaneous determination of sulfathiazole and sulfamethoxazole residues in food samples

In this study, we have developed a novel, hypersensitive, and ultraselective electrochemical sensor containing thermally annealed gold–silver alloy nanoporous matrices (TA-Au-Ag-ANpM) integrated with f-MWCNTs-CPE and poly(l-serine) nanocomposites for the simultaneous detection of sulfathiazole (SFT) and sulfamethoxazole (SFM) residues in honey, beef, and egg samples. TA-Au-Ag-ANpM/f-MWCNTs-CPE/poly(l-serine) was characterized using an extensive array of analytical (UV–Vis, FT-IR, XRD, SEM, and EDX), and electrochemical (EIS, CV and SWV) techniques. It exhibited outstanding performance over a wide linear range, from 4.0 pM to 490 μM for SFT and 4.0 pM to 520 μM for SFM, with picomolar detection and quantification limits (0.53 pM and 1.75 pM for SFT, 0.41 pM and 1.35 pM for SFM, respectively). The sensor demonstrated exceptional repeatability, reproducibility, and anti-interference capability, with percentage recovery of 95.6–102.4% in food samples and RSD below 5%. Therefore, the developed sensor is an ideal tool to address the current antibiotic residue crisis in food sources.

Estimating nitroxynil residues in food samples and surface water using two different sustainable chemical sensing techniques: Comparative greenness, whiteness, and blueness study

The presence of veterinary drug residues in edible animal tissues endangers human health and safety, accordingly, global nations enacted legislative restrictions to monitor their concentrations in food. In this work, we introduce two fluorimetric sensors for determining nitroxynil (NXL), a crucial veterinary medication, in various matrices. Sensor I, novel nitrogen and sulfur-doped carbon quantum dots (S,N-CQDs), was fabricated from strawberry and leek juices as cheap and sustainable natural resources. Only five minutes of microwave radiation were required as a rapid synthesizing technique without any drastic conditions or organic solvents. The S,N-CQDs manifest blue emission using λex/em of 340/418 nm. The synthesized nanosensor was characterized using UV Spectroscopy, transmission electron microscopy (TEM), and Fourier-transform infrared spectrometry (FTIR). Sensor II was the acriflavine reagent (AV) that exhibits native fluorescence using λex/em of 265/505 nm. Both sensors displayed quantitative turning off in their native fluorescence by increasing concentrations of NXL (1.0–10.0 and 0.5–8.0 µg mL−1) with correlation coefficients r = 0.9998 and 0.9999 for sensors I and II, respectively. The two probes achieved satisfactory percentage recoveries and standard deviation (SD < 4) for NXL assessing in complex matrices of diverse food samples (bovine muscle, kidney, and fat) and Fasciolar® veterinary formulation. Additionally, they have been successfully used to detect the investigated drug in river ecosystems with a mean %recovery of 100.10 ± 1.70, and 99.95 ± 1.31 for sensors I and II, respectively. The two constructed sensors’ specificity has been confirmed for all tested matrices reflecting their feasibility as promising platforms in therapeutic drug monitoring, livestock ecosystems, food safety assurance, quality control of drugs, and environmental pollution monitoring. Quenching mechanisms for both methodologies were studied and the reaction stoichiometry for NXL − AV complex was calculated in two ways. Lastly, a comprehensive comparison was performed between the suggested methodologies and published fluorimetric works. The greenness feature was assessed by the Analytical Eco-scale (AES), Green Analytical Procedure Index (GAPI), and Analytical GREEnness Metric Approach (AGREE). In addition, white analytical chemistry principles were checked to assess sustainability criteria using the RGB 12 algorithm. The recently launched Blue Applicability Grade Index (BAGI) metric tool was also employed to assess the practicality (Blueness) character.

Quantifying pesticide residues in food matrices using statistical methods

Traditional techniques for pesticide residues detection and quantification in food using mass spectrometry often require the analysis of standards for each compound, leading to time-consuming and laborious procedures, especially considering that these methods usually involve hundreds of pesticides to be targeted. This paper presents a novel approach to compound quantitation, where multiple target compounds can be accurately quantified using few predictor compounds, significantly reducing the experimental time and minimizing resource requirements. For this purpose, data on detector response which encompassed calibration slopes of a total of 96 pesticide standards on GC-MS/MS and 66 standards on LC-MS/MS, over a period of 4 years, were collected. Two fundamental statistical techniques, Pearson correlation and linear regression, were used to create a predictive model, which accuracy was further evaluated using R-square, adjusted R-square, and Root Mean Square Error (RMSE). Four predicted compounds for the LC dataset and seven predicted compounds for GC dataset were identified, and various predictor combinations were considered. A linear regression model was developed using predictor combinations to estimate the calibration slope of each of the target compound. This model was applied for the quantitation of several pesticide residues in food samples. The results validated the model’s high accuracy.

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.

A novel electrochemical sensor for the detection of metronidazole residues in food samples

The widespread use and misuse of antibiotics in pharmaceuticals and animal farming has resulted in their accumulation in food sources and the environment, posing significant threats to human health, the environment, and the global economy. In this study, we have developed a hypersensitive, and ultra-selective electrochemical sensor, the first of its kind, by integrating a thermally annealed gold-silver alloy nanoporous matrix (TA-Au-Ag-ANpM) with reduced graphene oxide (r-GO) and poly(glycine) at the surface of a glassy carbon electrode (GCE). This sensor aims to detect life-threatening metronidazole (MTZ) residues in food samples. TA-Au-Ag-ANpM/r-GO/poly(glycine)/GCE was thoroughly characterized using a range of analytical techniques, including UV–Vis, FT-IR, XRD, SEM, and EDX. Furthermore, its electrochemical properties were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The sensor exhibited outstanding performance, with a broad linear range of 2.0 pM–410 μM. The limits of detection (LOD) and quantification (LOQ) were determined to be 0.0312 pM and 0.104 pM, respectively. The TA-Au-Ag-ANpM/r-GO/poly(glycine)/GCE exhibited exceptional reproducibility, repeatability, stability, and resistance to interferences. Moreover, the sensor demonstrated outstanding performance in detecting MTZ residues in milk powder, pork, and chicken meat samples, achieving very good recoveries (96.9%–101.4%) with a relative standard deviation (RSD) below 5%. This performance highlights the potential for practical applications in food safety and quality monitoring. Therefore, the developed sensor contributes to the advancement of electrochemical sensing technology and its application in ensuring food safety and integrity by combating antibiotic residues.

Rapid testing of antibiotic residues to increase food safety awareness of animal origin.

Antibiotics are used to improve growth, reduce disease, and decrease mortality in animals grown for food. The government regulates and prohibits the use of antibiotics, in particular, the use of antibiotic growth promoter (AGP) in livestock; however, it is not yet known whether the use of antibiotics is in accordance with regulations so that there are no antibiotic residues in food of animal origin. To ensure food safety of animal origin and to raise awareness of food safety, it is necessary to detect antibiotic residues in fish, eggs, and chicken meat from Yogyakarta Special Province through monitoring and monitoring. To ensure food safety and regulatory compliance in food samples, antibiotic residue screening techniques are essential. A number of methods, such as time-consuming and costly chromatographic and spectroscopic methods, have been developed for the detection of antibiotic residues in food samples; however, not all laboratories have these facilities. Therefore, a rapid diagnosis of food of animal origin is required. The purpose of this study was to rapidly test antibiotic residues by using Premi®test kits (R-Biopharm AG, Germany) to increase awareness of food safety of animal origin. We tested 345 animal-based food samples from traditional markets, supermarkets, and central markets in five districts of Yogyakarta Special Province for antibiotic residues using rapid test kits and observation questionnaires to identify risk factors. The presence of antibiotic residues in food-animal origin samples from the Yogyakarta region had an antibiotic residue level of 9.28% (32/345), consisting of fish samples 11.3% (18/97), eggs 15.65% (1/114), and chicken meat samples 0.87% (13/102). The highest percentage of samples positive for residual antibiotics was 21.9% (7/32) from supermarket meat samples. The highest amounts of antibiotic residues were found in fish samples collected from Sleman Regency, up to 25% (8/32), whereas in supermarket fish samples, there were as high as 18.8% (6/32). Antibiotic residues in animal-based food can be attributed to various factors, including product source, transportation conditions, and environmental conditions. The widespread distribution of antibiotic residues in fish comes from environmental conditions during maintenance, distribution, and retailing. Monitoring antibiotic residue prevalence in food-animal origins, particularly chicken meat, eggs, and fish, is crucial for improving animal food quality and safety.

Gold screen-printed electrodes coupled with molecularly imprinted conjugated polymers for ultrasensitive detection of streptomycin in milk

Antibiotic resistance is a global health threat, challenging traditional treatments and complicating the food safety process. This study introduces an electrochemical detection method for streptomycin sulfate, utilizing gold screen-printed electrodes (Au-SPE) functionalized via electropolymerization of a custom-made naphthalene diimide-based conjugated monomer (Th2-NDI-PIA). This modification creates specific binding sites for streptomycin, allowing rapid detection of the antibiotic. The sensor's response to different concentrations of streptomycin was studied via Differential Pulse Voltammetry (DPV) in a wide linear range from 10-13 M to 10-9 M, with a limit of detection (LoD) of 0.190 ± 0.005 pM. The imprinted electrode demonstrates selectivity to other antibiotics, but also to common interferents that can be found in milk such as lactose, glucose, riboflavin, and bisphenol A. Successful proof-of-principle in whole cow milk highlights the sensor's efficacy in detecting antibiotic residues in food samples, offering a promising alternative for a rapid and portable detection technique.

Magnetic solid-phase extraction based on restricted-access molecularly imprinted polymers for ultrarapid determination of ractopamine residues from food samples by capillary electrophoresis

An ultrafast, efficient, and eco-friendly method combining magnetic solid phase extraction and capillary electrophoresis with diode array detection have been developed to determine ractopamine residues in food samples. A restricted access material based on magnetic and mesoporous molecularly imprinted polymer has been properly synthesized and characterized, demonstrating excellent selectivity and high adsorbent capacity. Short-end injection capillary electrophoresis method was optimized: 75 mM triethylamine pH 7 as BGE, -20 kV, 50 mbar by hydrodynamic injection during 8 s, and capillary temperature at 25 °C; reaching ultrafast ractopamine analysis (∼0.6 min) with good peak asymmetry, and free from interfering and/or baseline noise. After sample preparation optimization, the conditions were: 1000 µL of sample at pH 6, 20 mg of adsorbent, stirring time of 120 s, 250 µL of ultrapure water as washing solvent, 1000 µL of methanol: acetic acid (7: 3, v/v) as eluent, and the adsorbent can be reused four times. In these conditions, the analytical method showed recoveries around to 100 %, linearity ranged from 9.74 to 974.0 µg kg−1, correlation coefficient (r) ≥ 0,99 in addition to adequate precision, accuracy, and robustness. After proper validation, the method was successfully applied in the analysis ractopamine residues in bovine milk and bovine and porcine muscle.

A novel IgE epitope-specific antibodies-based sandwich ELISA for sensitive measurement of immunoreactivity changes of peanut allergen Ara h 2 in processed foods.

Peanut is an important source of dietary protein for human beings, but it is also recognized as one of the eight major food allergens. Binding of IgE antibodies to specific epitopes in peanut allergens plays important roles in initiating peanut-allergic reactions, and Ara h 2 is widely considered as the most potent peanut allergen and the best predictor of peanut allergy. Therefore, Ara h 2 IgE epitopes can serve as useful biomarkers for prediction of IgE-binding variations of Ara h 2 and peanut in foods. This study aimed to develop and validate an IgE epitope-specific antibodies (IgE-EsAbs)-based sandwich ELISA (sELISA) for detection of Ara h 2 and measurement of Ara h 2 IgE-immunoreactivity changes in foods. DEAE-Sepharose Fast Flow anion-exchange chromatography combining with SDS-PAGE gel extraction were applied to purify Ara h 2 from raw peanut. Hybridoma and epitope vaccine techniques were employed to generate a monoclonal antibody against a major IgE epitope of Ara h 2 and a polyclonal antibody against 12 IgE epitopes of Ara h 2, respectively. ELISA was carried out to evaluate the target binding and specificity of the generated IgE-EsAbs. Subsequently, IgE-EsAbs-based sELISA was developed to detect Ara h 2 and its allergenic residues in food samples. The IgE-binding capacity of Ara h 2 and peanut in foods was determined by competitive ELISA. The dose-effect relationship between the Ara h 2 IgE epitope content and Ara h 2 (or peanut) IgE-binding ability was further established to validate the reliability of the developed sELISA in measuring IgE-binding variations of Ara h 2 and peanut in foods. The obtained Ara h 2 had a purity of 94.44%. Antibody characterization revealed that the IgE-EsAbs recognized the target IgE epitope(s) of Ara h 2 and exhibited high specificity. Accordingly, an IgE-EsAbs-based sELISA using these antibodies was able to detect Ara h 2 and its allergenic residues in food samples, with high sensitivity (a limit of detection of 0.98 ng/mL), accuracy (a mean bias of 0.88%), precision (relative standard deviation < 16.50%), specificity, and recovery (an average recovery of 98.28%). Moreover, the developed sELISA could predict IgE-binding variations of Ara h 2 and peanut in foods, as verified by using sera IgE derived from peanut-allergic individuals. This novel immunoassay could be a user-friendly method to monitor low level of Ara h 2 and to preliminary predict in vitro potential allergenicity of Ara h 2 and peanut in processed foods.

Amide and carboxyl dual-functionalized magnetic microporous organic networks for efficient extraction of cephalosporins

Cephalosporins (CEFs) are a class of widely used toxic antibiotics. Development of a rapid and sensitive method for detecting trace CEF residues in food samples is still challenging. Herein, we report preparation of an amide and carboxyl groups dual-functionalized core-shelled magnetic microporous organic network MMON-COOH-2CONH for efficient magnetic solid-phase extraction (MSPE) of CEFs from milk powder samples. Under optimal conditions, the established MMON-COOH-2CONH-MSPE-HPLC-UV method owns wide linear range (3–10000 µg kg−1), low limits of detection (1–3 µg kg−1), large enrichment factors (93.9–99.4), low adsorbent consumption (3 mg), and short extraction time (6 min). Synergistic extraction mechanisms of ionic bonding, hydrogen bonding, π-π, and hydrophobic interactions were elucidated by both theoretical density functional theory calculations and experimental data. This study confirms that preparation of dual-functionalized MMONs and introduction of ionic groups are feasible to promote MMONs application in sample pretreatment.

Preparation and recognition mechanism study of an scFv targeting chloramphenicol for a hybridization chain reaction-CRISPR/Cas12a amplified fluoroimmunoassay

Recombinant antibody-based immunoassays have emerged as crucial techniques for detecting antibiotic residues in food samples. Developing a stable recombinant antibody production system and enhancing detection sensitivity are crucial for their biosensing applications. Here, we bioengineered a single-chain fragment variable (scFv) antibody to target chloramphenicol (CAP) using both Bacillus subtilis and HEK 293 systems, with the HEK 293-derived scFv demonstrating superior sensitivity. Computational chemistry analyses indicated that ASP-99 and ASN-102 residues in the scFv play key roles in antibody recognition, and the hydroxyl group near the benzene ring of the target molecule is critical for in antibody binding. Furthermore, we enhanced the scFv's biosensing sensitivity using an HCR-CRISPR/Cas12a amplification strategy in a streptavidin-based immunoassay. In the dual-step amplification process, detection limits for CAP in the HCR and HCR-CRISPR/Cas12a stages were significantly reduced to 55.23 pg/mL and 3.31 pg/mL, respectively. These findings introduce an effective method for developing CAP-specific scFv antibodies and also propose a multi-amplification strategy to increase immunoassay sensitivity. Additionally, theoretical studies also offer valuable guidance in CAP hapten design and genetic engineering for antibody modification.

An applied potential powered screen-printed electrode for sensitive EC-SERS detection of acetamiprid

Acetamiprid (AAP) is a common neonicotinoid pesticide and their residues have emerged as a widely concerned issue on vegetables and fruits. In this work, a facile electrochemical surface-enhanced Raman spectroscopy (EC-SERS) method with one step of “mixing and detection” was proposed for detection of AAP. Wherein, screen printed electrode (SPE) was modified by dropping silver nanoparticles (AgNPs) onto the SPE surface. Compared to the normal SERS detection, the EC-SERS had a 5-fold enhancement in SERS signal with an applied potential at –0.7 V. Under the optimal applied potential, a wide linear range from 0.1 μM to 1000 μM was achieved with a low limit of detection (LOD, 0.04 μM), about 7-fold lower than that of the normal SERS method (LOD, 0.31 μM). Density functional theory (DFT) calculation revealed that the van der Waals force between AAP molecules and AgNPs was greatly enhanced. Besides, the EC-SERS method was successfully applied for the detection of AAP in Brassica chinensis L., and the results correlated well (R2 =0.9760) with those obtained from liquid chromatography-tandem mass spectrometry (HPLC-MS). The proposed method featured in easy operation, rapid detection and high sensitivity, which can act as a promising tool for monitoring pesticide residues in food samples.

An ultra-sensitive electrochemical sensing platform based on nanoflower-like Au/ZnO array on carbon cloth for the rapid detection of the nitrite residues in food samples

In this work, we constructed an enhanced electrochemical signal sensing platform using Au/ZnO nanoflake arrays coated on carbon cloth for the rapid detection of nitrite in food. Based on a stepwise synthesis strategy of electrodeposition and magnetron sputtering technique, AuNPs were sputtered onto ZnO nanoflower-like array sheets. Combining the high catalytic performance of AuNPs with the morphology of ZnO significantly increased the surface area and electrocatalytic activity of the electrodes. The prepared sensor showed a linear response range of 0.2–4986 μΜ, a limit of detection of 0.09 μM, and a high sensitivity of 5677 μA mM−1 cm−2. It is worth noting that the sensor can precisely detect nitrite in the presence of interfering substances and has excellent stability and reproducibility. In addition, the nitrite residues in several food samples were analyzed using this method and spectrophotometric method, and the results of the two methods were not significantly different.

Highly sensitive ratiometric fluorescence detection of tetracycline residues in food samples based on Eu/Zr-MOF

The development of a simple, rapid, and sensitive method for monitoring antibiotic residues is crucial for maintaining food safety. Herein, a ratiometric fluorescence probe based on bimetallic organic framework (Eu/Zr-MOF) was developed for the detection of tetracycline (TC). The Eu/Zr-MOF was synthesized by the coordination of Eu3+ and Zr4+ with 2-APDC, which exhibited a grape-like cluster morphology and dual-emitting fluorescence at 430 nm/616 nm. Based on the internal filtering effect (IFE), significant fluorescence quenching was observed at 430 nm, whereas only slight changes occurred at 616 nm. The ratiometric sensing offered two broad linear ranges (0.5–8 μg/mL; 10–60 μg/mL) and a low detection limit (26.7 ng/mL). The proposed method was applied to the determination of TC in pork and water samples. Fluorescent sensors have the advantages of simple design, fast response, and high sensitivity, thus providing a promising means for evaluating the safety of food contaminated with TC.

Cobalt ferrite/semiconducting single-walled carbon nanotubes based field-effect transistor for determination of carbamate pesticides

Carbaryl and carbofuran are the carbamate pesticides which have been widely used worldwide to control insects in crops and house. If the pesticides entered in to the food products and drinking water, they could cause serious health effects in humans. Therefore, the development of a rapid, simple, sensitive and selective analytical device for on-site detection of carbamates is crucial to evaluate food and environmental samples. Recently, semiconducting single-walled carbon nanotube-based field effect transistors (s-SWCNT/FETs) have shown several advantages such as high carrier mobility, good on/off ratio, quasi ballistic electron transport, label-free detection and real-time response. Herein, cobalt ferrite (CFO) nanoparticles decorated s-SWCNTs have been prepared and used to bridge the source and drain electrodes. As-prepared CFO/s-SWCNT/FET had been used for the non-enzymatic detection of carbaryl and carbofuran. When used as a sensing platform, the CFO/s-SWCNT hybrid film exhibited high sensitivity, and selectivity with a wide linear range of detection from 10 to 100 fMand the lowest limit of detections for carbaryl (0.11 fM) and carbofuran (0.07 fM) were estimated. This sensor was also used to detect carbaryl in tomato and cabbage samples, which confirmed its practical acceptance. Such performance may be attributed to the oxidation of carbamates by potent catalytic activity of CFO, which led to the changes in the charge transfer reaction on the s-SWCNTs/FET conduction channel. This work presents a novel CFO/s-SWCNT based sensing system which could be used to quantify pesticide residues in food samples.

Rapid and sensitive detection of tetracycline residue in food samples using Cr(III)-MOF fluorescent sensor

As tetracycline antibiotics were used in the poultry sector, their residue in edible animal products may adversely affect food safety and human health. The development of selective and sensitive tetracycline sensors has garnered a lot of interest due to the complexity of food samples. Therefore, a fluorescent sensing probe based on chromium(III)-metal–organic framework was developed for the rapid detection of tetracycline. After the addition of tetracycline, blue emission at λem 410 nm was effectively quenched by the interaction between TC and Cr(III)-metal–organic framework material. Under optimized conditions (sensor concentration: 30 mg/L and pH: 10.0), the sensing probe showed a fast response time (1 min), and low detection limit (0.78 ng/mL) with a linear range (5–45 ng/mL). Interestingly, the Cr(III)-metal–organic framework was successfully applied to quantity tetracycline residue in chicken meat and egg samples with recoveries of 95.17–06.93%. To deduce, our work can provide a new strategy for the direct detection of tetracycline in food samples.