RESUMEN
In this work, an imidazolium-based poly (ionic liquid) (poly(1-octyl-3-vinyl- imidazolium naphthalene sulfonate)) functionalized silica (poly(C8VIm+NapSO3-) @SiO2) was successfully prepared for the determination of parabens in food samples. The prepared poly(C8VIm+NapSO3-)@SiO2 was characterized by Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectrogram (XPS) and Scanning electron microscopy (SEM). The simulation calculation results indicated that the suitable binding energies were between the polymeric ionic liquids and parabens, and the main interactions for extraction were hydrogen bonding, electrostatic and π-π stacking interactions. In addition, compared with commercial extraction materials, the prepared poly(C8VIm+NapSO3-)@SiO2 sorbent showed comparable or even better extraction performance towards parabens. The effective parameters were optimized by a combination of the univariate method and Box-Behnken design (BBD). Under the optimum conditions, coupled with high performance liquid chromatography (HPLC), wide linear ranges (1.0-800 µg L-1), good linearity (R2 ≥ 0.9997) and low limits of detection (0.1 µg L-1) were obtained. In addition, the intra-day and inter-day relative standard deviations (RSDs) were all lower than 6.3%. Moreover, the proposed method was successfully used for the determination of parabens in food samples and satisfactory recoveries in the range of 76.9-97.4% were obtained. The results indicated that the proposed method had good sensitivity, accuracy and precision for the detection of parabens in food samples.
Asunto(s)
Líquidos Iónicos , Líquidos Iónicos/química , Dióxido de Silicio/química , Parabenos/análisis , Espectroscopía Infrarroja por Transformada de Fourier , Adsorción , Extracción en Fase Sólida/métodos , Cromatografía Líquida de Alta Presión/métodos , Límite de DetecciónRESUMEN
Recently, covalent organic frameworks (COFs) have been widely used to prepare magnetic adsorbents for food analysis due to their highly tunable porosity, large specific surface area, excellent chemical and thermal stability and large delocalised π-electron system. This review summarises the main types and preparation methods of magnetic COFs and their applications in food analysis for the detection of pesticide residues, veterinary drugs, endocrine-disrupting phenols and estrogens, plasticisers and other food contaminants. Furthermore, challenges and future outlook in the development of magnetic COFs for food analysis are discussed.
Asunto(s)
Estructuras Metalorgánicas , Estructuras Metalorgánicas/química , Análisis de los Alimentos , Magnetismo , Porosidad , Fenómenos MagnéticosRESUMEN
The distributed driven agricultural vehicle platform studied in this paper is a basic carrying platform that can be used for a variety of agricultural activities (pesticide spraying, weeding, and other plant protection operations). It does not need to rely on traditional fuel engine to drive but is driven by electric power, which is more environmentally friendly and conducive to the development of ecological agriculture in the future. In this paper, according to the driving and structure characteristics of distributed driving electric agricultural vehicles, in order to ensure the vehicle trajectory tracking ability, under conditions of agricultural operation, the driving attitude and drive coordination control of electric agricultural vehicles are taken as the key research objectives. In this way, the driving path of the vehicle platform can be accurately controlled during the operation of pesticide spraying and herbicide, so as to reduce the excessive use or misuse of pesticides and herbicides and greatly reduce the field pollution. Considering the specific driving environment as well as complex and changeable motion patterns of agricultural vehicles, when a single motion model is used to track and estimate the driving state, there will be low filtering accuracy or even loss of the target during vehicle maneuvering. In this paper, interactive multiple model (IMM) algorithm is combined with extended Kalman filter to effectively track changes of the target's motion mode, thereby avoiding low filtering accuracy or serious state estimation inaccuracy. Finally, through the distributed electric drive agricultural operation experimental platform developed by the research group, the working conditions close to the actual agricultural production activities was set up according to the needs of actual agricultural production activities in this paper, and applicability and accuracy of the algorithm state estimation are verified by experiments.
Asunto(s)
Conducción de Automóvil , Emisiones de Vehículos , Agricultura , Electricidad , Movimiento (Física)RESUMEN
In this work, a polymeric imidazolium-embedded octadecyl ionic liquid (poly(1-vinyl-3-octadecylimidazolium naphthalene sulfonate))-grafted silica (poly(C18VIm+NapSO3-)@SiO2) sorbent was prepared and applied as a solid-phase extraction (SPE) sorbent in extraction of flavonoids. The synthesized poly(C18VIm+NapSO3-)@SiO2 sorbent was characterized by X-ray photoelectron spectrogram (XPS) and fourier transform infrared spectroscopy (FT-IR). The thermodynamic and kinetic adsorption models of the prepared poly(C18VIm+NapSO3-)@SiO2 sorbent towards flavonoids were discussed by nonlinear fitting adsorption curve and the results indicated the thermodynamic adsorption model in this work was tended to be Freundlich model rather than Langmuir one and the pseudo-second order model could be used to describe the dynamic adsorption process. In addition, the adsorption amounts indicated the sorbent has satisfactory extraction capabities towards flavonoids. For investigating the influence of independent variables and their interactions on the extraction efficiency, a Box-Behnken design was used for optimizing three greatly influential parameters after performing single-factor experiments. The interaction energies between flavonoids and two ionic liquids were calculated to understand the adsorption mechanism. Under the optimal conditions, a method used for determining flavonoids was developed by combining SPE technique with high performance liquid chromatography (HPLC), and the developed method exhibited low limits of detection (0.25-0.4⯵g L-1), good linearities with correlation coefficients (R2) in the range of 0.9951-0.9996 and satisfactory recoveries ranging from 83.6% to 114.1%, which confirmed the proposed method could be successfully used to determine trace flavonoids in real samples.