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Abstract This study aimed to develop a highly efficient nanocomposite composed of magnetic chitosan/molybdenum disulfide (CS/MoS2/Fe3O4) for the removal of three polycyclic aromatic hydrocarbons (PAHs)—pyrene, anthracene, and phenanthrene. Novelty was introduced through the innovative synthesis procedure and the utilization of magnetic properties for enhanced adsorption capabilities. Additionally, the greenness of chitosan as a sorbent component was emphasized, highlighting its biodegradability and low environmental impact compared to traditional sorbents. Factors influencing PAH adsorption, such as nanocomposite dosage, initial PAH concentration, pH, and contact time, were systematically investigated and optimized. The results revealed that optimal removal efficiencies were attained at an initial PAH concentration of 150 mg/L, a sorbent dose of 0.045 g, pH 6.0, and a contact time of 150 min. The pseudo-second-order kinetic model exhibited superior fitting to the experimental data, indicating an equilibrium time of approximately 150 min. Moreover, the equilibrium adsorption process followed the Freundlich isotherm model, with kf and n values exceeding 7.91 mg/g and 1.20, respectively. Remarkably, the maximum absorption capacities for phenanthrene, anthracene, and pyrene on the sorbent were determined as 217 mg/g, 204 mg/g, and 222 mg/g, respectively. These findings underscore the significant potential of the CS/MoS2/Fe3O4 nanocomposite for efficiently removing PAHs from milk and other dairy products, thereby contributing to improved food safety and public health.

Abstract This work compares the electroanalytical performance of two electroanalytical systems based on (1) the glassy carbon electrode (GCE), and (2) the electrified liquid–liquid interface (eLLI), for the detection of fluoroquinolone antibiotic–danofloxacin (DANO). Our aim was to define the optimal conditions to detect the chosen analyte with two employed systems, extract a number of electroanalytical parameters, study the mechanism of the charge transfer reactions (oxidation at GCE and ion transfer across the eLLI), and to provide physicochemical constants for DANO. Detection of the chosen analyte was also performed in the spiked milk samples. To the best of our knowledge, this is the first work that directly compares the electroanalytical parameters obtained with solid electrode (in this case GCE) and eLLI. We have found that for DANO the latter provides better electroanalytical parameters (lower LOD and LOQ) as well as good selectivity when the milk was analyzed.

This study aimed to develop a highly efficient nanocomposite composed of magnetic chitosan/molybdenum disulfide (CS/MoS2/Fe3O4) for the removal of three polycyclic aromatic hydrocarbons (PAHs)—pyrene, anthracene, and phenanthrene. Novelty was introduced through the innovative synthesis procedure and the utilization of magnetic properties for enhanced adsorption capabilities. Additionally, the greenness of chitosan as a sorbent component was emphasized, highlighting its biodegradability and low environmental impact compared to traditional sorbents. Factors influencing PAH adsorption, such as nanocomposite dosage, initial PAH concentration, pH, and contact time, were systematically investigated and optimized. The results revealed that optimal removal efficiencies were attained at an initial PAH concentration of 150 mg/L, a sorbent dose of 0.045 g, pH 6.0, and a contact time of 150 min. The pseudo-second-order kinetic model exhibited superior fitting to the experimental data, indicating an equilibrium time of approximately 150 min. Moreover, the equilibrium adsorption process followed the Freundlich isotherm model, with kf and n values exceeding 7.91 mg/g and 1.20, respectively. Remarkably, the maximum absorption capacities for phenanthrene, anthracene, and pyrene on the sorbent were determined as 217 mg/g, 204 mg/g, and 222 mg/g, respectively. These findings underscore the significant potential of the CS/MoS2/Fe3O4 nanocomposite for efficiently removing PAHs from milk and other dairy products, thereby contributing to improved food safety and public health. [ABSTRACT FROM AUTHOR]

This work compares the electroanalytical performance of two electroanalytical systems based on (1) the glassy carbon electrode (GCE), and (2) the electrified liquid–liquid interface (eLLI), for the detection of fluoroquinolone antibiotic–danofloxacin (DANO). Our aim was to define the optimal conditions to detect the chosen analyte with two employed systems, extract a number of electroanalytical parameters, study the mechanism of the charge transfer reactions (oxidation at GCE and ion transfer across the eLLI), and to provide physicochemical constants for DANO. Detection of the chosen analyte was also performed in the spiked milk samples. To the best of our knowledge, this is the first work that directly compares the electroanalytical parameters obtained with solid electrode (in this case GCE) and eLLI. We have found that for DANO the latter provides better electroanalytical parameters (lower LOD and LOQ) as well as good selectivity when the milk was analyzed. [ABSTRACT FROM AUTHOR]

A smart material based on ferrofluid deep eutectic solvents graphene oxide magnetite (MGO-DES FF) was successfully synthesized by adding choline chloride-thymol DES as carrier solvent onto MGO composite for the determination of ofloxacin in egg and milk samples. The synthesized materials were characterized using Fourier transform-infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibration sample magnetometer (VSM) to evaluate their functional groups, morphological and magnetic properties, respectively. The MGO-DES FF material was used as ferrofluid sorbent for liquid phase microextraction (LPME) of ofloxacin prior to UV–Vis spectrophotometry analysis. Several parameters were optimized including the type of DES, ferrofluid composition, ferrofluid volume, desorption solvent type and volume, pH, and extraction time to study their effects on the recovery percentage of ofloxacin. Under optimum conditions, good linearity was achieved between the range of 1 – 10 mg L−1 for ofloxacin and a correlation coefficient of 0.9963. The LOD and LOQ values recorded were 0.75 and 1.55 µg L−1, respectively. The RSD% for intra-day and inter-day were 2.64 and 7.40, respectively. The recovery percentage for milk and egg samples was ranging from 80.8 to 92.0%. Based on the results obtained, the developed MGO-DES FF LPME method demonstrated excellent sensitivity and efficiency for the extraction of ofloxacin in food samples. It showed great potential as an alternative method for the extraction of pharmaceutically active contaminants in the challenging matrix. [ABSTRACT FROM AUTHOR]

AbstractAn ultrasonic-assisted liquid-liquid microextraction pretreatment method was developed using magnetic nanoparticles and deep eutectic solvent, and employed to separate the Norfloxacin and Enrofloxacin from pure milk samples by ultraviolet-high performance liquid chromatography. A DES-based ferromagnetic fluid with strong extraction power was prepared through the ultrasonic treatment of deep eutectic solvent (HBA: HBD = 1:2) and magnetic nanoparticles. The exceptional repeatability, reproducibility and long-term stability effect was mainly achieved through the strong interactions between the extractant and the analyte, such as hydrophobic interaction, hydrogen bond attraction, and electrostatic interaction. The results showed that the Norfloxacin and Enrofloxacin presented good linear relationship within the concentration range of 0.005 ∼ 500 mg/mL, with detection limits of 0.00035 mg/mL. The method was successfully applied to determine Norfloxacin and Enrofloxacin in milk samples by HPLC with acceptable recovery of 81 ∼ 104% and relative standard deviations (RSD) below 3%. The established method was simple, rapid and efficient, making it applicable for the detection of Norfloxacin and Enrofloxacin residues in milk. The results of this study were compared with reported methods in the literature revealing its advantages. [ABSTRACT FROM AUTHOR]

Hg2+, a highly toxic heavy metal, poses significant environmental and health risks, necessitating rapid detection methods. In this study, we employed an electrochemical aptasensor for rapid and sensitive detection of Hg2+ based on DNA strands (H2 and H3) immobilized graphene aerogels-Au nanoparticles (GAs-AuNPs) hybrid recognition interface and exonuclease III (Exo III)-mediated cyclic amplification. Firstly, Gas-AuNPs were modified on the surface of the ITO electrode to form a sensing interface to increase DNA loading and accelerate electron transfer. Then, DNA helper was generated with the addition of Hg2+ via Exo III-mediated cycling. Finally, the hairpin structures of H2 and H3 were opened with the DNA helper, and then the methylene blue (MB) functionalized DNA (A1 and A2) combined with the H2 and H3 to form an H-shaped structure. The current response of MB as an electrochemical probe was proportional to the concentration of Hg2+. Under optimal conditions, the aptasensor showed excellent performance for Hg2+, achieving a linear range from 1 fM to 10 nM and a detection limit of 0.16 fM. Furthermore, the aptasensor was used to detect Hg2+ in spiked milk samples, achieving a high recovery rate and demonstrating promising application prospects. [ABSTRACT FROM AUTHOR]

In present work, an efficient, reliable and accurate analytical method has been used for the extraction of five organophosphorus pesticides (diazinon, chloropyrifos, phosalone, parathion-methyl and azinphos-methyl) from milk samples. The extracted analytes were determined with high performance liquid chromatography-diode array detector. For this purpose, the milk proteins are precipitated by trichloroacetic acid and the analytes dissolved in the supernatant phase are adsorbed onto an octadecyl silane sorbent. Then, acetone is contacted with the sorbent to elute the analytes and then it is mixed with toluene. The mixture is rapidly dispersed into deionised water filled into a syringe. To break down the obtained cloudy solution, 250 µL acetonitrile is added to the solution as a demulsifier. Finally, the collected organic phase in the tip of the syringe is collected, evaporated and reconstituted in mobile phase for using in determination of the analytes. Figure of merits were calculated for method validation and acceptable limits of detection (0.17–0.36 ng mL–1) and quantification (0.57–1.34 ng mL–1), high enrichment factors (395–460) and extraction recoveries (79–92%) were obtained. Inter- (n = 6) and intra-day precisions at a concentration of 3 ng mL–1 (each analyte) with relative standard deviations ≤7.2%, was obtained. Lastly the method was successfully used for determination of the analytes in some milk samples and chloropyrifos was found in one sample. [ABSTRACT FROM AUTHOR]

A sensitive, straightforward, and inexpensive dispersive micro solid-phase extraction (DµSPE) coupled with the spectrophotometric method was developed for measuring celecoxib in biological and water samples. For this purpose, a new sorbent (Nickel nanoparticles doped carboxyl graphene oxide) was synthesized using a simple chemical procedure and was utilized to extract celecoxib. The effective factors in the DµSPE procedure were evaluated and optimized by the design of experiment method. Two designs, including the Plackett-Burman design and Box-Behnken design, were applied to screening significant factors and to optimize the significant factors, respectively. The DµSPE- spectrophotometric method was linear in the concentration range of 0.004-3.5 µg mL-1 with an R-squared of 0.9951 for the celecoxib measurement under the optimum conditions. The method showed a low limit of detection of 0.004 µg mL-1 and a suitable enrichment factor of 21.7 for the analyte determination. The relative standard deviation was calculated for five measurements of the standard solution of celecoxib with a concentration of 0.3 µg mL-1 and was 3.2%. Finally, the proposed method was used to analyze real samples such as milk, urine, and tap water samples, indicating that the method is very suitable for measuring celecoxib in real samples with a recovery in the range of 90.3-96.8% with a relative standard deviation lower than 5.1 %. The important advantages of the method are simple and inexpensive procedure, low desorption solvent and sorbent consumption, and without the need for sophisticated and expensive instruments.

Hg2+, a highly toxic heavy metal, poses significant environmental and health risks, necessitating rapid detection methods. In this study, we employed an electrochemical aptasensor for rapid and sensitive detection of Hg2+ based on DNA strands (H2 and H3) immobilized graphene aerogels-Au nanoparticles (GAs-AuNPs) hybrid recognition interface and exonuclease III (Exo III)-mediated cyclic amplification. Firstly, Gas-AuNPs were modified on the surface of the ITO electrode to form a sensing interface to increase DNA loading and accelerate electron transfer. Then, DNA helper was generated with the addition of Hg2+ via Exo III-mediated cycling. Finally, the hairpin structures of H2 and H3 were opened with the DNA helper, and then the methylene blue (MB) functionalized DNA (A1 and A2) combined with the H2 and H3 to form an H-shaped structure. The current response of MB as an electrochemical probe was proportional to the concentration of Hg2+. Under optimal conditions, the aptasensor showed excellent performance for Hg2+, achieving a linear range from 1 fM to 10 nM and a detection limit of 0.16 fM. Furthermore, the aptasensor was used to detect Hg2+ in spiked milk samples, achieving a high recovery rate and demonstrating promising application prospects.

A new metal–organic framework heterostructure composite (MOF@MOF, ZIF-8@PCN-128Y) was synthesized by an internal extension growth method and used as a sensor for the detection of tetracycline (TC). In this method, TC was enriched by virtue of the adsorption capacity of ZIF-8 and detected by PCN-128Y acting as an optical tentacle in virtue of its luminescence advantage. TC was rapidly detected with sensitivity and selectivity, and the limit of detection was 60 nM. At the same time, this method has good linearity and a wide linear range. TC in milk and beef samples was determined by this sensor, and the recovery rate was 94.2–106.3%. This work provided guidance for the construction and application of the MOF@MOF fluorescence sensor. [ABSTRACT FROM AUTHOR]

The study was conducted to evaluate the effect, consistency, and economic viability of using different brands and dilution levels of liquid anionic surfactants to detect Mastitis in dairy cattle. Fifty-five milk samples were collected and subjected to macroscopic evaluation at a cattle farm located in Sta. Maria, Bulacan, Philippines. Milk samples were brought to the Philippine Carabao Center National Headquarters and Genepool Science City of Muñoz, Nueva Ecija for Somatic Cell Count. The experiment used 10 treatments with 3 replications arranged in a Completely Randomized Design. The macroscopic evaluation results showed that liquid anionic surfactants at 30%-50% dilution levels could detect Mastitis in dairy cattle. This was validated by the somatic cell count results from PCC Dairy Laboratory. On the other hand, statistical analysis results revealed that the treatments and the control (commercial mastitis test) were comparable except for brand Z at a 40% dilution rate. Brand Z at 30% and 50% dilution rate were found to be consistent among other treatments in detecting Mastitis in dairy cattle. In terms of economic viability, brand X and brand Y at 30% were the cheapest and had the lowest production cost and highest percentage savings. The study was conducted to evaluate the effect, consistency, and economic viability of using different brands and dilution levels of liquid anionic surfactants to detect Mastitis in dairy cattle. Fifty-five milk samples were collected and subjected to macroscopic evaluation at a cattle farm located in Sta. Maria, Bulacan, Philippines. Milk samples were brought to the Philippine Carabao Center National Headquarters and Genepool Science City of Muñoz, Nueva Ecija for Somatic Cell Count. The experiment used 10 treatments with 3 replications arranged in a Completely Randomized Design. The macroscopic evaluation results showed that liquid anionic surfactants at 30%-50% dilution levels could detect Mastitis in dairy cattle. This was validated by the somatic cell count results from PCC Dairy Laboratory. On the other hand, statistical analysis results revealed that the treatments and the control (commercial mastitis test) were comparable except for brand Z at a 40% dilution rate. Brand Z at 30% and 50% dilution rate were found to be consistent among other treatments in detecting Mastitis in dairy cattle. In terms of economic viability, brand X and brand Y at 30% were the cheapest and had the lowest production cost and highest percentage savings.

Milk samples consumed in the world contain essential nutrients as well as toxic elements. Quality control is necessary for the production and processing of milk samples. Also, transportation and storage conditions have effects on the composition of samples. In this study, the concentrations of zinc, iron, chromium, nickel, copper, cadmium and lead in fourteen different brands of milk samples (pasteurized and long life) purchased from markets of Turkey in Ankara were determined and evaluated by using flame and electrothermal atomic absorption spectrometers (FAAS, ETAAS). Graphite furnace heating program for Cd and Pb determinations in samples was optimized in the absence or presence of nickel (Ni) matrix modifier. The limits of detection (LOD) for Cd and Pb determined by electrothermal atomic absorption spectrometry (ETAAS) in the presence of Ni matrix modifier were 1.2 and 1.5 μg/L, respectively. The LODs of Cu, Fe, Zn, Cr and Ni determined by flame atomic absorption spectrometry were 18.4, 71.2, 20.8, 2.1 and 2.3 μg/L, respectively. The mean concentrations and standard deviations (×̅±s) of Zn, Ni, Cu, Cr, Fe, Cd and Pb were 1.7 ± 0.4 mg/kg, 0.24 ± 0.08 mg/kg, 0.8 ± 0.2 mg/kg, 0.8 ± 0.6 mg/kg, 1.9 ± 0.6 mg/kg, 46 ±5 μg/kg and 28 ± 3 μg/kg, respectively found in fourteen different milk samples. The contents of elements found in samples were compared with permissible limits recommended in the health criteria by the World Health Organization (WHO) and literature values. It was concluded that the tools and materials used in milk production were not caused to heavy metal contamination. The metal concentrations in the milk samples were within the limits of the maximum permissible metal values given by WHO/FAO, other regulations and the Turkish Food Codex. [ABSTRACT FROM AUTHOR]

Abstract Background The analysis of the quality of food is important to protect humans from food-borne or food-based illnesses caused by pathogens, such as bacteria, fungi, viruses, and protozoa. Rapid identification of these pathogens is critical to ensure food safety. Various detection and identification strategies exist; however, they are laborious and time consuming and hence the detection takes longer time. The aim of this study was to develop the specific and fast method for the detection of contaminants in milk. Results In this study, we have developed a simple paper-based PCR method with minimum sample preparation process. The 16S rDNA universal primers were used for the detection of bacterial contaminants. LacZ primers were used for coliform detection which causes serious illness and hence their detection is crucial. ITS region primers were used for fungal detection. The most unique thing about this study is use of Whatman paper no. 1 as sample carrier material. We developed and validated the paper-based PCR method and used it for the detection of microbes and coliforms using milk as a representative sample. Conclusion We evaluated this method for its suitability in the detection of contaminant microbes using different milk samples. The paper-based method could successfully detect contaminants in the milk samples and the results were comparable to the traditional microbial detection method. The traditional microbiological method takes at least 18–20 h for detecting the presence of microbes in any sample but the developed paper-based PCR method can confirm the microbial presence in 2–3 h. This is very promising especially in the testing where sample sterility is crucial.

[Display omitted] • Biogenic amines were studied at the electrified water-1,2-dichloroethane interface. • PEA and TRA can be determined at the polarized liquid–liquid interface. • Electrochemical method for Real-Time Monitoring of Milk Spoilage process is proposed. This study involved an investigation into the electrochemical characteristic of a few biogenic amines (BAs) occurring at the polarized interface between two immiscible electrolyte solutions (ITIES) with ion transfer voltammetry (ITV). The main focus of this research was the comprehensive electroanalytical and physicochemical analysis of phenylethylamine (PEA), allowing the determined of the formal Galvani potential of the ion transfer reaction (Δ org aq Φ ′), diffusion coefficients (D), formal free Gibbs energy of the ion transfer reaction (Δ G ′ a q → o r g ) and water-1,2-dichloroethane partition coefficient (log P water / D C E PEA ). Furthermore, the collected data were employed to calculate analytical parameters, including voltametric detection sensitivity, limits of detection and the target analyte quantification. Moreover, the influence of the presence of 7 other BAs (histamine, spermine, spermidine, putrescine, cadaverine, tyramine and tryptamine) on the recorded signals originating from the PEA ion transfer was checked. The feasibility of the developed method was corroborated through experimentation with milk samples. Additionally, utilizing the devised methodology, an electrochemical assessment of the spoilage progression in milk samples was undertaken. [ABSTRACT FROM AUTHOR]

A magnetic nanoparticle (MNP)-based lateral flow immunochromatography assay (LFIA) was established to detect fluoroquinolones (FQs) in milk. This method is an improvement of traditional Au nanoparticle (AuNP)-based LFIA. Compared with AuNP-labeled antibody, the combination between MNPs and antibody is stronger and more stable, and the preparation process is convenient. In this study, the color intensity of MNPs-LFIA test strip was analyzed, which laid a research foundation for magnetic quantitative analysis and high sensitivity analysis of LFIA. The limits of detection (LODs) for 10 FQs in phosphate buffer (PB) solution ranged from 1 to 5 ng/mL, and in milk ranged from 2 to 20 ng/mL. The recovery in spiked milk sample ranged from 16.47 to 83.67%. The log functions of analyte concentration and T/C value were fitted into a linear equation. The specificity of the MNPs-LFIA is satisfactory, without cross-reaction with antibiotics from other chemical classes. The results of this method are consistent with those of ultra-performance liquid chromatography-mass spectrometry, indicating the MNPs-LFIA method is reliable and accurate. As far as we know, this is the first time that MNPs-LIFA has been applied to the detection of FQs in milk. [ABSTRACT FROM AUTHOR]

This study explored the synthesis and application of amino-functionalised magnetic silica (Fe 3 O 4 @mSiO 2 -NH 2) nanocomposite as a selective sorbent for the extraction of penicillin antibiotics (PENs) from milk samples via magnetic micro-solid phase extraction (M-µ-SPE). The physicochemical characteristics of the synthesised sorbent were evaluated through important spectroscopy analyses. The adopted M-µ-SPE conditions were: 25 mg of Fe 3 O 4 @mSiO 2 -NH 2 ; pH 4; 3 min of extraction time; 1 min of desorption time; acetonitrile as the desorption solvent; 10% of salt addition; and 30 mL sample. Under the optimum conditions, the developed method demonstrated satisfactory from 10 to 500 µg/L (r 2 ≥0.9986), low limits of detection (2.5–3.1 µg/L), high analytes recovery (85.2–106.7%), and good precision (RSDs≤8%, n = 5). The proposed method is rapid, simple, inexpensive, and shows good sensitivity when compared to previously developed methods. This study provides new insight into the development of a new sorbent for PENs and new microscale sample preparation for monitoring PENs in complex milk matrices. [Display omitted] • The Fe 3 O 4 @mSiO 2 -NH 2 sorbent was synthesised and characterised. • Fe 3 O 4 @mSiO 2 -NH 2 was used as an efficient sorbent for the M-µ-SPE method. • The method presented high efficiency, accuracy, and precision for PENs. • The method was assessed through AGREEprep and Analytical Eco-scale metric tools. [ABSTRACT FROM AUTHOR]

78 individual milk samples (IS) were taken in the Czech Fleckvieh and Holstein dairy cow herds and 33 bulk milk samples (BS) were taken in 13 Holstein dairy cow herds to compare two methods for the determination of fatty acids (FAs) – routine/indirect (infrared (IR) spectroscopy, MIR-FT) and reference/direct (gas chromatography, GC). The IS results show that the fatty acids C16:0 and C18:1 and the group of saturated (SFA) and unsaturated (UFA) FAs can be determined using routine method with a relatively high reliability (correlations (r) 0.7543, 0.7607, 0.8424 and 0.9492; P < 0.001). In case of polyunsaturated FAs is the r lower (0.2891; P < 0.05). In BS the tightness of relations is stronger in the case of the SFA and UFA (r 0.7094; 0.9389; P < 0.001), while for the group of TFA (trans isomers of unsaturated FAs) and PUFA (polyunsaturated FAs) are lower r (0.5897 and 0.5931; P < 0.001 respectively). Routine method for fatty acids profile determination is efficient for selection of raw milk to guarantee the production of specific dairy products with increased content of healthful fatty acids.

Background: The analysis of the quality of food is important to protect humans from food-borne or food-based illnesses caused by pathogens, such as bacteria, fungi, viruses, and protozoa. Rapid identification of these pathogens is critical to ensure food safety. Various detection and identification strategies exist; however, they are laborious and time consuming and hence the detection takes longer time. The aim of this study was to develop the specific and fast method for the detection of contaminants in milk. Results: In this study, we have developed a simple paper-based PCR method with minimum sample preparation process. The 16S rDNA universal primers were used for the detection of bacterial contaminants. LacZ primers were used for coliform detection which causes serious illness and hence their detection is crucial. ITS region primers were used for fungal detection. The most unique thing about this study is use of Whatman paper no. 1 as sample carrier material. We developed and validated the paper-based PCR method and used it for the detection of microbes and coliforms using milk as a representative sample. Conclusion: We evaluated this method for its suitability in the detection of contaminant microbes using different milk samples. The paper-based method could successfully detect contaminants in the milk samples and the results were comparable to the traditional microbial detection method. The traditional microbiological method takes at least 18–20 h for detecting the presence of microbes in any sample but the developed paper-based PCR method can confirm the microbial presence in 2–3 h. This is very promising especially in the testing where sample sterility is crucial. [ABSTRACT FROM AUTHOR]

An aptamer (Apt) functionalized magnetic material was prepared by covalently link Apt to Fe3O4/graphene oxide (Fe3O4/GO) composite by 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide hydrochloride and N‐hydroxysuccinimide, and then characterized by FTIR spectroscopy, X‐ray diffraction, and vibration sample magnetometry. The obtained composite of Fe3O4/GO/Apt was employed as magnetic solid‐phase extraction adsorbent for the selective preconcentration of sulfadimethoxine prior to analysis by high‐performance liquid chromatography. Under the optimal conditions (sample pH of 4.0, sorbent dosage of 20 mg, extraction time of 3 h, and methanol‐5% acetic acid solution as eluent), a good linear relationship was obtained between the peak area and concentration of sulfadimethoxine in the range of 5.0 to 1500.0 µg/L with correlation coefficient of 0.9997. The limit of detection (S/N = 3) was 3.3 µg/L. The developed method was successfully applied to the analysis of sulfadimethoxine in milk with recoveries in the range of 75.9‐92.3% and relative standard deviations less than 8.1%. The adsorption mechanism of Fe3O4/GO/Apt toward sulfadimethoxine was studied through the adsorption kinetics and adsorption isotherms, and the results show that the adsorption process fits well with the pseudo‐second‐order kinetic model and the adsorbate on Fe3O4/GO/Apt is multilayer and heterogeneous. [ABSTRACT FROM AUTHOR]

The first objective of this study was to determine whether differences would occur among teat end preparation techniques with regard to potential contamination of milk samples collected for bacterial culture. The second objective was to determine whether differences would be detected in genus or species of bacteria isolated from samples collected using the various methods as well as from contaminated or uncontaminated samples. Mammary quarter foremilk samples were collected from lactating dairy cattle at the University of Missouri Foremost Research Dairy Farm (Columbia). Four different teat end preparation methods were used to compare contamination rates in milk samples. Sampling techniques used before milk collection included (1) no preparation, (2) pre-milking disinfection and single-use towel drying of teats only, (3) scrubbing of the teat end with alcohol only, and (4) pre-milking disinfection, single-use towel drying, and scrubbing of the teat end with alcohol. Milk was plated on Columbia blood agar. Cultures were read at 48 h, with the number of morphologically different bacterial colony types quantified and isolated. Isolates were identified using MALDI-TOF mass spectrometry. Median numbers of colony types were compared among groups using Kruskal-Wallis ANOVA with post-hoc pairwise comparisons, and proportional data were compared using the chi-squared test. A total of 168 cows, including 665 quarters, were sampled, and 1,614 isolates resulted. Analysis with MALDI-TOF identified 29 unique genera and 81 unique species among the samples. More contaminated samples occurred in groups 1 and 2 compared with groups 3 and 4. Group 3 had more contaminated samples than group 4. The majority of Pseudomonas spp. isolates were identified within group 2. When applying previously described niches to Staphylococcus spp., environmental species were more likely to be identified among contaminated samples, whereas host-adapted species were more likely to be identified among uncontaminated samples. These data confirm that scrubbing the teat end with alcohol after pre-milking disinfection with an iodine-based teat disinfectant and drying of the teat minimizes contamination of the milk sample. [ABSTRACT FROM AUTHOR]

A Pd/Al layered double hydroxide/carboxymethyl cellulose nanocomposite (CMC@Pd/Al-LDH) was fabricated using carboxymethyl cellulose as a green substrate via co-precipitation method. The synthesized nanocomposite was characterized using different methods such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, transmission electron microscopy, and electrochemical techniques. A glassy carbon electrode (GCE) was then modified with the suspended composite to obtain an electrochemical sensor for hydrogen peroxide (H2O2). The voltammetric (cathodic) current of the modified GCE was measured at −380 mV (vs. Ag/AgCl), at the scan rate of 50 mV.s−1. Results show a linear dynamic range of 1 to 120 μM, and a 0.3 µM limit of detection (at S/N = 3). Intraday and interday relative standard deviations are in the ranges of 4.9–5.4% and 6.8–7.3%, respectively. The sensor was applied for the determination of H2O2 in basil extracts, milk, and spiked river water samples. The recoveries are between 96.60 and 102.30%. [ABSTRACT FROM AUTHOR]

A nanocomposite consisting of platinum particles, polyaniline and Ti3C2 MXene (Pt/PANI/MXene) was used to modify a screen-printed carbon electrode (SPCE) to obtain sensors for hydrogen peroxide and lactate. This nanocomposite was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) to determine the physical morphologies and the nanocomposite elements. The modified electrode exhibited the improved current response towards hydrogen peroxide (H2O2) compared with an unmodified electrode and provided a low detection limit of 1.0 μM. When lactate oxidase was immobilized on the modified electrode, the electrode responded to lactate via the H2O2 generated in the enzymatic reaction. The lactate assay was performed by amperometry at a constant potential of +0.3 V (vs. Ag/AgCl). The linear range was found to be from 0.005 to 5.0 mM with a detection limit of 5.0 μM for lactate. Ultimately, this biosensor was used for the determination of lactate in milk samples with high stability and reliability. [ABSTRACT FROM AUTHOR]

Abstract Explorations of how the complex microbial communities that inhabit different body sites might contribute to health and disease have prompted research on the ways the harmonious relationship between a host and its microbiota could be used to keep animals healthy in their production conditions. In particular, there is a growing interest in the bacterial signatures that can be found in the milk of healthy or mastitic dairy cows. The concept of sterility of the healthy mammary gland of dairy ruminants has been challenged by the results of studies using bacterial DNA-based methodology. The newly obtained data have led to the concept of the intramammary microbiota composed of a complex community of diverse bacteria. Accordingly, mammary gland infections are not mere infections by a bacterial pathogen, but the consequence of mammary dysbiosis. This article develops the logical implications of this paradigm shift and shows how this concept is incompatible with current knowledge concerning the innate and adaptive immune system of the mammary gland of dairy ruminants. It also highlights how the concept of mammary microbiota clashes with results of experimental infections induced under controlled conditions or large field experiments that demonstrated the efficacy of the current mastitis control measures.

78 individual milk samples (IS) were taken in the Czech Fleckvieh and Holstein dairy cow herds and 33 bulk milk samples (BS) were taken in 13 Holstein dairy cow herds to compare two methods for the determination of fatty acids (FAs) – routine/indirect (infrared (IR) spectroscopy, MIR-FT) and reference/direct (gas chromatography, GC). The IS results show that the fatty acids C16:0 and C18:1 and the group of saturated (SFA) and unsaturated (UFA) FAs can be determined using routine method with a relatively high reliability (correlations (r) 0.7543, 0.7607, 0.8424 and 0.9492; P < 0.001). In case of polyunsaturated FAs is the r lower (0.2891; P < 0.05). In BS the tightness of relations is stronger in the case of the SFA and UFA (r 0.7094; 0.9389; P < 0.001), while for the group of TFA (trans isomers of unsaturated FAs) and PUFA (polyunsaturated FAs) are lower r (0.5897 and 0.5931; P < 0.001 respectively). Routine method for fatty acids profile determination is efficient for selection of raw milk to guarantee the production of specific dairy products with increased content of healthful fatty acids. [ABSTRACT FROM AUTHOR]

Abstract Herein, a simple electrochemical sensor is proposed for 17β-estradiol (E2) determination. In this sensing platform, split DNA aptamers for E2 were applied as recognizing agents. In the presence of E2, split aptamers are bound to E2 and establish split1-E2-split2 complex as a bridge on the surface of electrode. This physical bar leads to ultrasensitive detection of E2. This aptasensor is capable of recognizing E2 within 30 min without complicated procedures and expensive equipment. This sensing approach indicated a wide linear range with detection limits of 0.5 pM and 0.7 pM for E2 in tap water and milk samples, respectively. Simplicity and high specificity of the proposed electrochemical aptasensor make it an ideal sensing platform for ultra-low detection of other targets in complicated samples by replacement of split DNA aptamers. Highlights • A simple electrochemical sensor was proposed for 17β-estradiol (E2) determination. • In this sensing platform, split DNA aptamers for E2 were applied as recognizing agents. • E2-mediated bridge assembly leads to ultrasensitive detection of E2. • This aptasensor is capable of recognizing E2 within 30 min without complicated procedures. • This aptasensor indicated detection limits of 0.5 pM and 0.7 pM for E2 in tap water and milk samples, respectively. [ABSTRACT FROM AUTHOR]

The present study determined trends in the isolation of bacterial pathogens in milk samples submitted from clinical mastitis buffaloes at the University mastitis laboratory during 2007 to 2016. Culture results (n = 3945) were classified into six categories (Staphylococcus spp., 28.7%; Streptococcus spp., 1%; Corynebacterium spp., 1.1%; gram-negative organisms, 3.2%; others including mixed growths, 3.3%; and no growth, 62.7%). Overall, culture results were significantly associated with year (χ2 = 112.28; df = 10; P < 0.001) and season (χ2 = 136.03; df = 20; P < 0.001). From 2007–2009 to 2013–2016, the isolation of Staphylococcus spp. increased from 28.2 to 48.4%, while isolation of Streptococcus spp. (50 to 20%) and Corynebacterium spp. (65.1 to 16.3%) decreased. The proportion of samples characterized as no growth increased from 26.4% (2007–2009) to 46.3% (2013–2016). Further, the proportion of clinical mastitis cases increased over the study years (goodness-of-fit χ2 = 59; df = 2; P < 0.001). With respect to season, the proportion of Staphylococcus spp. (30.6%; 346/1132), Corynebacterium spp. (48.8%; 21/43), and gram-negative bacteria (55.9%; 71/127) were more associated with the monsoon, and that of Streptococcus spp. (47.5%; 19/40) with the winter. Seasonal effects were also observed on the occurrence of clinical mastitis cases; comparatively, more clinical mastitis cases (35.6%; 523/1473) were observed during the monsoon season (goodness-of-fit χ2 = 276.7; df = 4; P < 0.001) as compared with other seasons. The present study concludes that Staphylococcus spp. are the major cause of intramammary infections in buffaloes with clinical mastitis, demanding more studies regarding its epidemiology and pathogenicity. Also, more efforts are needed in the prevention and control of clinical mastitis in buffaloes, especially, during the monsoon season. [ABSTRACT FROM AUTHOR]

Highlights • Water compatible magnetic molecularly imprinted polymer (MMIP) was prepared. • MMIP based matrix solid phase dispersion (MSPD) was used for melamine. • The dispersant sorbent could be reused at least three times. • MSPD variables were simply effectively optimized by experimental design. • Along with simplicity, MMIP-MSPD-HPLC method was applicable to milk sample. Abstract This paper reports a new variant of sample clean-up procedure based on miniaturized matrix solid phase dispersion (MSPD) combining with water compatible magnetic molecularly imprinted polymers (MMIP) for preconcentration of melamine from milk samples prior high-performance liquid chromatography with UV detection. By employing MMIP as dispersant sorbent matrix interferences could be eliminated completely and the column packing step was interestingly omitted that decreasing in glassware expenditure, labor effort and extraction time which cause improvement of the method performance. In order to investigate the functionality, morphology and magnetic properties of the prepared MMIP, it was fully characterized by FT-IR, VSM, SEM, and TEM. Multivariate optimization was applied as a versatile statistical approach for evaluating the influence of the main variables and their interactions on extraction efficiency. Under optimized conditions, the proposed method exhibited a wide linear response in the concentration range of 250.0–5000.0 μg L−1, satisfactory recoveries for all samples (86.6% ≤), and supreme repeatability (RSD less than 6.3%) were achieved as well. The low limit of detection close to 67.0 μg L−1 implied high ability of proposed method for isolation of melamine from complicate milk sample. These befitting results demonstrated that the developed method is unique in terms of the facility, rapidly and least solvent consumption as well as accurate analysis of melamine at trace levels. [ABSTRACT FROM AUTHOR]

Herein, an electrochemical aptasensor is described for detection of ampicillin (Ampi). The sensing strategy is based on the application of a ladder-shaped DNA structure as a multi-layer physical block on the surface of gold electrode. Attributing to the electrostatic repulsion and physical prevention of the ladder-shaped DNA structure, ultrasensitive detection of Ampi was achieved with a detection limit as low as 1 pM. In the presence of Ampi, the ladder-shaped DNA structure is disassembled and detached from the electrode surface. This leads to the high access of [Fe(CN) 6 ]3-/4- as a redox indicator to the electrode surface and a strong redox peak. The aptasensor response for Ampi detection was in the linear range from 7 pM to 100 nM with the detection limit of 1 pM. The presented analytical strategy showed its application in detecting Ampi in the spiked milk samples with satisfactory performance. This work can be easily expanded for different targets by alternating the corresponding aptamers. • An ultrasensitive electrochemical aptasensor was described for detection of ampicillin (Ampi). • The aptasensor was based on the application of a ladder-shaped DNA structure on the surface of gold electrode. • The detection limit of aptasensor was 1 pM for Ampi. • The sensor showed its application in detecting Ampi in the spiked milk samples with satisfactory performance. [ABSTRACT FROM AUTHOR]

A novel magnetic adsorbent Fe3O4/reduced graphene oxide‐carbon nanotubes, was prepared by one‐pot solvothermal synthesis method. It was characterized by scanning electron microscopy, X‐ray powder diffraction and vibrating sample magnetometry. The diameter of Fe3O4 microparticles was about 350 nm, which were covered by carbon nanotubes and reduced graphene oxide sheets, while carbon nanotubes inserted between the reduced graphene oxide sheets effectively prevented their aggregation. The composite had large surface area and good magnetic property, suiting for magnetic solid‐phase extraction and the determination of sulfonamides, by coupling with high‐performance liquid chromatography. Under the optimized conditions (including extraction time, amount of adsorbent, solution pH, ionic strength and desorption conditions), a good linear was achieved in the concentration range of 5–500 μg/L and the low limits of detection and low limits of quantification were 0.35–1.32 and 1.16–4.40 μg/L, respectively. The enrichment factors were estimated to be 24.72 to 30.15 fold. The proposed method was applied for the detection of sulfonamides in milk sample and the recoveries were 88.4–105.9%, with relative standard deviations of 0.74–5.38%. [ABSTRACT FROM AUTHOR]

A synthetic polyethylene glycol-molybdenum disulfide (PEG@MoS2) composite was prepared using a simple method, and the application of this material in dispersive solid-phase extraction (DSPE) was investigated for the enrichment of eight sulfonamides (SAs) in milk samples. The composite was characterized by energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller measurements. The results showed that the MoS2 synthesized in the presence of PEG has the advantage of a larger surface area and that the adsorption effect of this MoS2 was enhanced. After extraction, the eight SAs were separated by capillary zone electrophoresis with a good linear relationship (R2 > 0.9902) in the range of 0.3–30 µg ml−1 and good precision (between 0.32% and 9.83%). Additionally, good recoveries (between 60.52% and 110.91%) were obtained for the SAs in the milk samples. The developed PEG@MoS2-based DSPE method could be applied for the enrichment of SAs in real milk samples.