期刊导航

Totally found 2572 items.

  • [期刊] Two-dimensional Au@Ag nanodot array for sensing dual-fungicides in fruit juices with surface-enhanced Raman spectroscopy technique
    The design of a novel and reliable plasmonic platform for detecting multiple chemical contaminants in the complex matrix is an exciting topic in the food industry. Herein, a high-performance surface-enhanced Raman scattering (SERS) two-dimensional (2D) nanodot array was designed through liquid-liquid interfacial self-assembly of the core-shell nanoparticles (Au@Ag NPs) and exploited for assessment of dual-fungicides in pear, apple, and orange juices. The 2D Au@Ag nanodot array delivered good uniformity and reproducibility with the substrate-to-substrate relative standard deviation values of 10.51%. This substrate could be used for detecting thiram and thiabendazole in aqueous solutions with the limit of detection of 0.0011 and 0.051 ppm, respectively. Furthermore, satisfactory recoveries ranging from 76-134% for the juices were obtained, demonstrating that the high-throughput 2D Au@Ag nanodot arrays are promising for their applications as sensitive SERS platforms for monitoring chemical contaminants in food products, especially in the beverage industry. All rights reserved, Elsevier.
  • [期刊] Ultrasound-assisted deep eutectic solvent as green and efficient media combined with functionalized magnetic multi-walled carbon nanotubes as solid-phase extraction to determine pesticide residues in food products
    A green and highly efficient ultrasound-assisted deep eutectic solvent extraction combined with functionalized magnetic multi-walled carbon nanotubes solid-phase extraction method for determination of seven pesticide residues in food products was developed. Various types of deep eutectic solvents (DESs) were screened for high extraction efficiencies and DES composing of proline and propylene glycol at 1:3 M ratio was selected as it exhibited highest yields. Extraction conditions were statistically optimized through response surface methodology using a Box-Behnken design. The established method was linear, precise, and accurate over the range of 0.1-50 μg mL-1. Limit of detection and limit of quantification were in the range of 0.02-0.05 μg mL-1 and 0.05-0.10 μg mL-1, respectively. The mean recoveries for pesticides ranged from 76.09 to 97.96% with relative standard deviation of 0.13-10.05%. The proposed method was successfully applied to analysis of the pesticides in real samples, which is a potentially promising technique for food matrix. All rights reserved, Elsevier.
  • [期刊] Newly designed molecularly imprinted 3-aminophenol-glyoxal-urea resin as hydrophilic solid-phase extraction sorbent for specific simultaneous determination of three plant growth regulators in green bell peppers
    A method based on solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC) was developed to determine the content of 4-chlorophenoxy acetic acid (PCPA), naphthylacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in green bell peppers. A molecularly imprinted 3-aminophenol-glyoxal-urea resin (MIAGUR) was first synthesized as a specific SPE adsorbent, which exhibited special selectivity and multiple adsorption interactions including hydrogen bonding and π-π interactions. The quantities of PCPA, NAA and 2,4-D in green bell peppers from 20 samples scattered throughout Baoding city (Hebei province, China) were determined using the proposed method. The results suggested that the use of PCPA, NAA and 2,4-D in green bell peppers from Baoding's markets is almost in fair. Moreover, MIAGUR-SPE-HPLC is suitable for the specific simultaneous monitoring of PCPA, NAA, and 2,4-D in green bell peppers and has potential applications in determination of PCPA, NAA, and 2,4-D of other plant products. All rights reserved, Elsevier.
  • [期刊] Simultaneous extraction of four plant growth regulators residues in vegetable samples using solid phase extraction based on thiol-functionalized nanofibers mat
    A simple and environmentally friendly sample pretreatment method was established for extraction of four plant growth regulators (PGRs) residues in vegetable samples. In order to effectively extract targets from complex sample matrices, three types of polar groups (COOH, NH2, or SH) functionalized polyacrylonitrile nanofibers mats (PAN NFsM) were prepared and evaluated, respectively. The superior -SH functionalized PAN NFsM was further selected as a novel adsorbent of solid phase extraction (SPE). Under optimal conditions, the proposed method could achieve high sensitivity (0.2-2 ng g-1) and acceptable recovery (88.94%-106.42%) by consuming lower amount of adsorbent (only 5 mg) and organic reagent (only 1.4 mL), and performing much fewer steps than current methods. In addition, the prepared SH-PAN NFsM possessed excellent reusability which could be reused for 6 times without degradation in adsorption capability. These results presented the great potential of the established method for environmental-friendly and efficiently detecting PGRs residues. All rights reserved, Elsevier.
  • [期刊] Rapid monitoring of pesticides in tomatoes (Solanum lycopersicum L.) during pre-harvest intervals by paper spray ionization mass spectrometry
    A rapid analysis of acephate, chlorpyrifos, and cyazofamid in tomato peels during pre-harvest intervals using paper spray ionization mass spectrometry (PSI-MS) has been demonstrated. LODs of 0.01 ppm and LOQs of 0.03 ppm were achieved. Relative standard deviations were below 9%, and recoveries close to 100%. For pesticides monitoring, samples were separated into stored and field groups. Stored group contained fruits that were harvested and stored at low temperature during the pre-harvest interval, and the field group contained fruits that were on the agricultural field over the pre-harvest interval. The decrease in pesticide amounts was lower for the stored samples. At the end of the pre-harvest intervals, acephate, chlorpyrifos, and cyazofamid were determined at 0.86, 0.96, and 0.23 ppm in the stored group, and at 0.26, 0.37, and 0.09 ppm in the field group, respectively. This work demonstrates the utility of PSI-MS for performing rapid quality control of fruit harvesting. All rights reserved, Elsevier.
  • [期刊] Development and validation of two robust simple chromatographic methods for estimation of tomatoes specific pesticides' residues for safety monitoring prior to food processing line and evaluation of local samples.
    Combination of pesticides; acetamiprid, flutolanil and etofenprox are usually used for tomato fruits for protecting them against pest infection. Generally, pesticides, residues could be one of the health hazard sources. Two specific simple sensitive chromatographic methods are developed for simultaneous estimation of the concerning pesticides' residues using simple economic steps of field sample preparation. The first method is HP-TLC method. Hexane: methanol: acetone: glacial acetic acid (8:2:0.5:0.1, by volume) is proposed as a developing system. The second one is RP-HPLC. Acetonitrile: water (75:25, v/v) is proposed as a mobile phase. The recommended methods are completely validated regarding ICH guidelines. Their means percentages and standard deviations of accuracy range 100.32±0.89 to 99.27±0.9. The methods' repeatability and intermediate precision relative standard deviation percentages range 0.395-0.894. They are successfully applied for estimating the pesticides in pure and commercial forms and field samples.
  • [期刊] Validation of ultrasonic-assisted switchable solvent liquid phase microextraction for trace determination of hormones and organochlorine pesticides by GC-MS and combination with QuEChERS.
    QuEChERS and switchable solvent liquid phase microextraction (SS-LPME) were respectively used as pretreatment and preconcentration tools to allow trace determination of selected organochlorine pesticides and hormones by gas chromatography mass spectrometry (GC-MS). The effects of principal SS-LPME variables and their interactions were evaluated with a Box-Behnken experimental design. The limits of detection obtained by direct GC-MS determination were enhanced by about 33-115 folds under the optimized SS-LPME conditions. The SS-LPME method was applied to tap water, well water, lake water, medical wastewater and tea samples. Satisfactory recovery results were obtained for all but the tea samples using the conventional calibration plot. Matrix matched calibration standards were used to improve the percent recovery of analytes to almost 100% in the tea samples. The combined QuEChERS and SS-LPME method was applied to tomato samples and matrix matching was also used to significantly improve analyte recoveries.
  • [期刊] Effective enrichment and detection of plant growth regulators in fruits and vegetables using a novel magnetic covalent organic framework material as the adsorbents.
    The present research reported a facile strategy for the synthesis of a novel magnetic covalent organic frameworks (Fe3O4@COF(TpDA)) material and applied it as a sorbent for magnetic solid phase extraction of plant growth regulators from fruits and vegetables. The prepared Fe3O4@COF materials showed many attractive features involving large specific surface area (180.2 m2/g) and high saturation magnetization (62.3 emu/g), which enabled it an ideal sorbent for sample pretreatment. The experimental conditions affecting the extraction performance were optimized systematically, including eluent, amount of sorbent, adsorption time and desorption time. The extracted samples were detected by HPLC-DAD. Under the optimized conditions, the proposed method exhibited good linearity (R ≥0.9990) and low limits of detection (4.68-7.51 µg/L). Satisfactory recoveries were calculated to be 83.0-105.0%. Finally, the proposed method was successfully applied to determination of plant growth regulators in fruits and vegetables, indicating the potential prospect of the Fe3O4@COF(TpDA) materials in sample pretreatment.
  • [期刊] Thermophysical and Theological properties of sorbitol + ([mmim] (MeO)_2PO_2) ionic liquid solutions: Solubility, density and viscosity
    In this study, the solubility, density and viscosity of sorbitol as a sugar alcohol in the ([mmim]((MeO)(2)PO2 ) ionic liquid (IL) were measured. The results indicated that sorbitol is highly soluble in this IL. The Flory-Huggins model with an average value for the chi parameter was successfully applied to predict the solubility of sorbitol in IL. The thermodynamic properties such as enthalpy, entropy and Gibbs free energy of dissolution were obtained using experimental solubility data, which demonstrated that the dissolution process is endothermic and nonspontaneous and includes an entropy increase. In addition, the apparent molar volume, apparent molar expansion and thermal expansion coefficient were calculated. The study of the rheological behavior revealed that the sorbitol/IL solution is Newtonian and the Arrhenius, Litovitz, Orrick-Erbar-Type and Vogel-Fulcher-Tamman models were used to correlate the viscosity data.
  • [期刊] Characterisation of the molecular interactions between primary bile acids and fractionated lupin cotyledons (Lupinus angustifolius L.)
    Interactions between bile acids and plant-based materials, and the related feedback mechanisms in enterohepatic circulation, have been considered targets for lowering cholesterol. This study aimed to identify lupin compounds that interact with primary bile acids on molecular level. Lupin cotyledons were fractionated and bile acid ad-sorbing activities were investigated using in vitro digestion, equilibrium dialysis and kinetic analyses. Proteinand fibre-enriched fractions significantly (p = 0.05) adsorbed chenodesoxycholic acids (up to 2.33 mu mol/100 g DM). Alcohol purification showed that bile acid adsorption is independent of protein and fibre structures. Moreover, high adsorption was observed with an alcohol extract (6.97 mu mol chenodesoxycholic acids/100 g DM) that was rich in phytochemicals, such as flavonoids (1842 mg/100 g DM). These results suggest the formation of hydrophobic interactions between polyphenols and bile acids. Further studies of molecular mechanisms are required to define the contributions of polyphenols to the cholesterol-lowering actions of lupins.
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