Multifunctional polymeric microspheres were prepared using hyper-cross-linking chemistry combined with surface-initiated atom transfer radical polymerization. The synthesized microspheres exhibited good water dispersibility, a high surface area, and pH/thermo dual-responsiveness. Fluoroquinolones (FQs), which contains a hydrophilic piperazine ring and hydrophobic fluorine atoms, were used as target analytes to assess the performance of the microspheres as a sorbent for dispersive solid-phase extraction (d-SPE). The d-SPE experimental parameters, including extraction time, amount of microspheres, extraction temperature, and sample solution pH, as well as the desorption conditions, were systematically studied. Coupled with LCMS/MS, an analytical method for analysis of trace-level FQs in water samples was developed and validated. Under optimal conditions, linearity with correlation coefficients (r) of >0.99 was achieved in the concentration range of 0.02–10 μg L−1. The limits of detection and quantification for the selected FQs were 5.0–6.7 and 12–20 ng L−1, respectively. High recovery values (93.1%–97.2%), a high enrichment factor (˜180), and good precision (RSD < 8%, n = 6) were obtained for FQ determination in spiked purified water samples. It was proposed that hydrophilic–hydrophobic transition induced by stretching and shrinking of polymer chains under different pH and temperature conditions offered good control of the surface wettability and altered the extraction behavior. The developed method was validated and was successfully applied to the analysis of FQs in environmental water samples, meat and milk samples. These results demonstrated that the water-dispersible polymeric microspheres have good potential for use in separation and extraction techniques.

The state of water in foodstuffs is a guiding principle in food design, and the equilibrium concept of water activity (Aw) is ubiquitous. It is regarded as a primary variable or “hurdle” in preservation technology, and a key variable influencing chemical reaction during storage. However, the amount of water in any system differs as function of water activity depending whether it is determined by water sorption or desorption. Even though this hysteresis behaviour has already been described in the literature, no physical interpretation of its origin has yet been proposed with respect to detailed molecular organisation. This work shows, for two different food powders, gluten and a milk-based product that the hysteresis disappears when either go through their glass transition. A more complete DSC analysis for gluten during different sorption/desorption cycles demonstrates that the hysteresis is dependent on the ageing of the material, which evolves in the glassy state and is induced by structural relaxation.

In the meat industry there are some processes like drying or storage of salted meat products in which the knowledge of water sorption phenomena in salted proteins could be very useful. The sorption and desorption of most salted products is a singular process with three differentiated steps: a(w) < 0.75, a(w) = 0.75 and a(w) > 0.75. SAFES methodology allows the analysis of different elements in a system: the components, phases and states of aggregation in the food during the process to understand the process stages with a suitable level of complexity. It also analyzes the transport functions, chemical reactions and the phenomena occurring during the processing of the product. The aim of this paper is to analyze the sorption phenomena of water in salted proteins using the SAFES methodology for the three different steps of the water desorption process. Salted pork meat isotherms at different three different salt concentrations and three various temperatures were analyzed in order to observe differences between them, in terms of mass transport, reactions, etc. With SAFES methodology, differences in the behaviour of the system, depending on the amount of NaCl added to the pork meat were observed. Differences in mass fluxes were found in relation to temperature and NaCl concentration.

Norovirus infections are one of the most prominent public health problems of microbial origin in the U.S. and other industrialized countries. Surveillance is necessary to prevent secondary infection, confirm successful cleanup after outbreaks, and track the causative agent. Quantitative mass spectrometry, based on absolute quantitation with stable-isotope labeled peptides, is a promising tool for norovirus monitoring because of its speed, sensitivity, and robustness in the face of environmental inhibitors. In the current study, we present two new methods for the detection of the norovirus genogroup I capsid protein using electrospray and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The peptide TLDPIEVPLEDVR was used to quantify norovirus-like particles down to 500 attomoles with electrospray and 100 attomoles with MALDI. With MALDI, we also demonstrate a detection limit of 1 femtomole and a quantitative dynamic range of 5 orders of magnitude in the presence of an environmental matrix effect. Due to the rapid processing time and applicability to a wide range of environmental sample types (bacterial lysate, produce, milk, soil, and groundwater), mass spectrometry-based absolute quantitation has a strong potential for use in public health and environmental sciences.

A magnetic covalent organic framework nanocomposite (Fe₃O₄@COF(Tp-NDA)) was synthesized via a solvothermal method, used as a magnetic adsorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) from lake water, tea, coffee, and fried chicken, and detected using a high performance liquid chromatography-ultraviolet detector. The synthesized magnetic adsorbent was characterized via transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption–desorption isotherm analysis and vibrating sample magnetometry. Parameters that affected the extraction conditions and desorption conditions were optimized. Adsorption equilibrium could be attained within 3 min. The prepared magnetic material could be reused 10 times. The limits of detection and quantification were 0.05–0.25 μg L⁻¹ and 0.17–0.83 μg L⁻¹, respectively. The recovery was 74.6–101.8% with a relative standard deviation of below 4.2%. The method was successfully used to detect PAHs in various samples.

In the present work, dispersive micro-solid phase extraction (D-μ-SPE) method using magnetic graphene oxide tert-butylamine (GO/Fe₃O₄/TBA) nanocomposite, as an efficient sorbent, was applied for determining 2,4-dichlorophenoxyacetic acid (2,4-D) in water and food samples. Detection was carried out using high-performance liquid chromatography (HPLC) instrument. Influential parameters of D-μ-SPE such as sorbent and its amount, elution solvent and its volume, adsorption and desorption times and pH of sample solution were investigated and optimized. Under the optimized conditions, limit of detection and quantitation values were 0.007 and 0.02 μg/mL, respectively. Recovery data for several real samples were obtained within the range of 88.0–94.0% with a relative standard deviation (RSD) less than 7.5%. The proposed method was successfully applied to quantitative determination of 2,4-D in several vegetables and water samples.

A simple and rapid vortex-assisted magnetic solid phase extraction (VA-MSPE) method for the separation and preconcentration of ziram (zinc dimethyldithiocarbamate), subsequent detection of the zinc in complex structure of ziram by flame atomic absorption spectrometry (AAS) has been developed. The ziram content was calculated by using stoichiometric relationship between the zinc and ziram. Magnetic carboxylated nanodiamonds (MCNDs) as solid-phase extraction adsorbent was prepared and characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry and scanning electron microscopy (SEM). These magnetic carboxylated nanodiamonds carrying the ziram could be easily separated from the aqueous solution by applying an external magnetic field; no filtration or centrifugation was necessary. Some important factors influencing the extraction efficiency of ziram such as pH of sample solution, amount of adsorbent, type and volume of eluent, extraction and desorption time and sample volume were studied and optimized. The total extraction and detection time was lower than 10min The preconcentration factor (PF), the precision (RSD, n=7), the limit of detection (LOD) and limit of quantification (LOQ) were 160, 7.0%, 5.3µgL−1 and 17.5µgL−1, respectively. The interference of various ions has been examined and the method has been applied for the determination of ziram in various waters, foodstuffs samples and synthetic mixtures.

A solid-phase extraction method using Pb²⁺ion-imprinted polymer (Pb²⁺-IIP) nanoparticles combined with flame atomic absorption spectrophotometry (FAAS) was developed for the preconcentration and trace monitoring of lead ions in environmental samples. The Pb²⁺-IIP nanoparticles were obtained by precipitation polymerization of 4-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), 4-(2-pyridylazo) resorcinol (the lead-binding ligand), and lead ions (the template ion) in acetonitrile solution. The Pb²⁺-IIP nanoparticles were characterized by Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TGA/DTA), and by scanning electron microscopy (SEM). Different affecting parameters on the adsorption and desorption of this solid-phase extraction process were evaluated and optimized. Under the optimized conditions, the detection limit for the proposed method was found to be 0.9 μg L⁻¹, while the relative standard deviation (RSD) for five replicate measurements was calculated to be <4 %. For proving that the proposed method is reliable, a range of food and water samples with different and complex matrices was used.

A molybdenum disulfide(MoS2)-based core-shell magnetic nanocomposite (Fe₃O₄@MoS₂) was synthesized by the stepwise hydrothermal method. Two-dimension ultrathin MoS₂ sheets with a thickness of approximately 20 nm were grown in situ on the surface of Fe₃O₄ (∼200 nm). They were employed as an adsorbent for the magnetic solid-phase extraction (MSPE) of sulfonamide antibiotics (SAs) from water samples. High-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was used for SA quantitation. Extraction parameters, including the pH effect, amount of Fe₃O₄@MoS₂, extraction time, temperature, and desorption conditions, were systematically investigated. The electrostatic interaction between the positively charged SAs and negatively charged MoS₂ nanoparticles in the optimal extraction conditions enhanced the adsorption of SAs on the sorbent surface. Under chosen conditions, the proposed strategy achieved wide linear range of 1.0–1000 ng·L⁻¹ SAs, low limits of detection (LOD, 0.20–1.15 ng·L⁻¹, S/N = 3:1), good trueness (recoveries between 85.50–111.5%), satisfactory repeatability and reproducibility (relative standard deviation, <10%, n = 5), and excellent recoveries between 80.20% and 108.6% for SAs determination in spiked waste water samples. The proposed strategy was validated and successfully applied for the analysis of water, milk, pork meat and fish meat. The nanocomposites, which have the combined advantages of magnetic separation and high adsorption affinity toward SAs, are a promising sorbent for antibiotics extraction from real samples.

Herein, a novel Cu/CuFe₂O₄@iron-based metal-organic framework 88 A (Cu/CuFe₂O₄@MIL-88A(Fe)) was developed through a scalable hydrothermal strategy for the magnetic dispersive solid-phase extraction of chlorpyrifos and phosalone from water, fruit juice, and vegetable samples prior to corona discharge ion mobility spectrometry analysis. The resulting nanocomposite was characterized in detail, and thus the investigation indicated that the magnetic nanocomposite had good adsorption capacity, high surface area, dispersion, and superparamagnetic properties. In addition, the fabricated sorbent provided different interactions with the target analytes, (hydrogen bonding, hydrophobic contacts, and π-π stacking interactions) resulting in the improvement of extraction efficiency. The applied method based on Cu/CuFe₂O₄@ MIL-88A(Fe) was validated by investigating the affecting parameters, including the amount of magnetic nanocomposite (10.0 mg), sample pH (7.0), salt content (7.5 % w/v), extraction time (5 min), type of elution (150 μL of methanol), and desorption time (2 min). The linearity of the method was found to be in the range of 0.6–300.0 ng mL⁻¹ and 1.5–500.0 ng mL⁻¹, for chlorpyrifos and phosalone with the coefficient of determination of ≥0.9991. The limits of detections (LODs) of 0.2 and 0.5 ng mL⁻ ¹ were obtained for the determination of chlorpyrifos and phosalone, respectively. The relative standard deviation values (RSDs %) were calculated in the range of 4.4 %–6.1 % (intra-day, n = 5) and 6.3 %–8.0 % (inter-day, n = 3) for three days. Ultimately, the developed method was successfully applied for the extraction of the desired analytes from various spiked samples with acceptable recoveries (88.3–100.4 %).