Separation and determination of phenolic compounds using novel deep eutectic solvent-in-water microemulsion electrokinetic chromatography.

BACKGROUND: Microemulsion electrokinetic chromatography (MEEKC) is a mode of capillary electrophoresis with a wide range of applications in which microemulsion is utilized as background electrolyte to achieve the separation of analytes. Microemulsions are composed of oil droplets, aqueous buffer, surfactant, and co-surfactant. Currently, conventional organic reagents act as the most commonly used oil phase in microemulsions, which are unfriendly to the environment. Recently, deep eutectic solvent (DES) has become a new type of eco-friendly solvent due to its non-toxicity. Therefore, it is of great value to establish a new MEEKC method by replacing conventional organic reagents as the oil phase with DES. RESULTS: The novel DES/W MEEKC method was established for phenolic compounds in Senecio scandens samples. Single-factor experiments and response surface methodology were performed to systematically optimize the crucial parameters for the method, including the type and content of the oil phase, surfactant content, concentration of borax buffer, and pH of the background solution. Under the optimized conditions, satisfactory regression curves were established for all standard analytes with correlation coefficients ≥0.9990. The method featured high sensitivity and favorable accuracy, with the instrumental detection limit in the range of 0.22-1.04 µg/mL, and intraday and interday precision for migration time expressed as relative standard deviations of 0.18-0.82% and 1.25-2.50%, respectively. The DES/W MEEKC method was successfully applied to Senecio scandens with good recoveries of 87.72-106.99%. In conclusion, the newly established DES/W MEEKC method is highly efficient, green and environmentally friendly. SIGNIFICANCE: DES is considered a green and efficient solvent. The DES/W MEEKC method is highly efficient and environmentally friendly. Actually, the method provides a novel and effective analytical tool for the simultaneous separation and determination of multiple phenolic compounds, especially in complex plant matrices. In the future, the DES/W MEEKC method still has the prospect of being widely used in the separation of other complex phytochemicals.

Nontargeted metabolomics and enzyme inhibitory and antioxidant activities for chemical and biological characterization of jujube (Ziziphus jujuba) extracts.

The chemical and biologically active characterization of jujube samples (fruits, cores, and leaves) were carried out by the integrated nontargeted metabolomics and bioassay. Firstly, collision cross-section values of active compounds in jujubes were determined by ultrahigh-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry. Then, a multidimensional statistical analysis that contained principal component analysis, partial least squares-discriminant analysis and hierarchical clustering analysis was employed to effectively cluster different tissues and types of jujubes, making identification more scientific. Furthermore, angiotensin-converting enzyme (ACE) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) were used to evaluate the quality of jujubes from a double activity dimension. The analytical results obtained by using ACE and DPPH to evaluate the quality of jujube were different from multivariate statistics, providing a reference for the application of jujube. Therefore, integrating chemical and biological perspectives to evaluate the quality of jujube provided a more comprehensive evaluation and effective reference for clinical needs.

Two-step pressure injection-assisted online enrichment of herbicides from foods with affinity micelle sweeping by micellar electrokinetic chromatography.

A novel online two-step pressure injection-assisted stacking preconcentration method, which involves sweeping and affinity micelles in micellar electrokinetic chromatography was developed to simultaneously measure various organic anions. The micellar solution was a mixed solution that contained 0.3 mM didodecyldimethylammonium bromide and 20 mM borax. After the micellar solution was injected for 60 s, the tested analytes prepared in 20 mM borax were introduced into the capillary for 150 s. The key experimental factors that influenced the separation and sensitivity were investigated and optimized, including the concentration and injection time of the micellar solution, the concentration of borax in the sample solution, the concentration of sodium dodecyl sulfate and borax in the background electrolyte (BGE), the content of acetonitrile in the BGE and the injection time of the sample solution. Compared with typical injection methods, this method achieved sensitivity enhancement factors ranging from 85 to 97 under optimized conditions. Good linearity for matrix-matched calibration was established for all analytes with R2 values of 0.9986-0.9996. The intraday (n = 6) and interday (n = 6) precisions of the method were less than 2.85% when expressed as relative standard deviations. When the method was applied to analyze rice and dried ginger samples, analyte recoveries ranged from 85.81% to 106.59%. Through sweeping and affinity micelles, stacking preconcentration method was successfully employed to analyze trace amounts of fenoprop and 2,4-dichlorophenoxyacetic acid in rice and dried ginger samples.

Enzyme activity- and chemometrics-assisted comprehensive two-dimensional liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry for the analysis of honeysuckle.

A unique and effective comprehensive two-dimensional liquid chromatography system was established and applied for the analysis of bioactive components in honeysuckle. Under the optimal conditions, Eclipse Plus C18 (2.1 × 100 mm, 3.5 µm, Agilent) and SB-C18 (4.6 × 50 mm, 1.8 µm, Agilent) columns were chosen for the first dimension (1D) and the second dimension (2D) separation. The optimal flow rates of 1D and 2D were 0.12 mL/min and 2.0 mL/min, respectively. Additionally, the proportion of organic solution was optimized to enhance orthogonality and integrated shift, and full gradient elution mode was adopted to improve chromatographic resolution. Furthermore, a total of 57 compounds were identified by molecular weight, retention time and collision cross-section value obtained from ion mobility mass spectrometry. Based on the data obtained from the principal component analysis, partial least squares discriminant analysis, and hierarchical cluster analysis, the categories of honeysuckle in different regions were significantly different. Moreover, the half maximal inhibitory concentration values of most samples were between 0.37 and 1.55 mg/mL, and most samples were potent α-glucosidase inhibitors, which is better for the evaluation of the quality of drugs from two aspects of substance content and activity.

Influences of Ni Doping on the Morphology, Optical and Magnetic Properties of ZnO Nanostructures Synthesized by Solvothermal Process.

Pure and Ni-doped ZnO nanostructures have been synthesized by a solvothermal process. The structure, morphology and properties of as-synthesized samples have been investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), selected-area electron diffraction (SAED), UV-vis spectrometer as well as by vibrating sample magnetometer (VSM). XRD and EDS studies indicated that the as-prepared products were well-crystallized wurtzite hexagonal structure. The SEM and TEM images show that the individual Zn0.96Ni0.04O nanostructure is composed of several nanorods with average diameter of 200 nm and lengths of 500 nm. The structure and morphology analyses show that Ni doping can influence the nanostructures morphology, but cannot change the crystal structures of ZnO samples. The UV-vis spectra showed that Ni dopant can result in an appreciable blue-shift for the absorption edge of the Ni-doped ZnO samples. The band gap energy of the Zn0.96Ni0.04O nanostructure was about 3.23 eV. By magnetic measurements, it was observed that the pure ZnO nanostructure exhibits diamagnetic property while the sample of 4% Ni shows an obvious ferromagnetic behavior at room temperature due to the formation of solid solution Zn0.96Ni0.04O, sp-d and d-d carrier exchange interactions, and the presence of abundant defects and oxygen vacancies.

Analysis of limb segments length and body proportion of southern Chinese children and adolescents.

AIM: This cross-sectional study was designed to characterize by age the ratios of limb segments length to height and extremities-trunk ratio and body proportions of southern Chinese children. METHODS: Data were collected from students (n = 4715) from five school, aged 6-17 years, in the city of Chongqing. Their standing height, sitting height, arm span, forearm length, upper arm length, leg length, lower leg length, and ratios of extremities to trunk length were determined. RESULTS: Sitting height, forearm length, upper arm length, arm span, and lower leg length were highly correlated with standing height (r > 0.9; P < 0.05). The ratio of extremities to trunk increased till about 13 years of age for both genders. CONCLUSIONS: The length of extremities and their ratio to sitting height reflect regular changes of growth in Chinese children as their age, and limb segments length is highly correlated with height.