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991.
Pinxuan Huang Qiutao Liu Jiabo Wang Zhijie Ma Jinghua Lu Weijun Kong 《Journal of separation science》2019,42(2):491-500
Rapid, economic, and highly effective determination of multiple mycotoxins in complex matrices has given huge challenges for the analytical method. In this study, an economic analytical strategy based on sensitive and rapid ultrafast liquid chromatography coupled to hybrid triple quadrupole/linear ion trap mass spectrometry technique was developed for the determination of seven mycotoxins of different chemical classes (aflatoxin B1, B2, G1, and G2, ochratoxin A, T‐2 toxin, and HT‐2 toxin) in Polygonum multiflorum. Target mycotoxins were completely extracted using a modified quick, easy, cheap effective, rugged, and safe method without additional clean‐up steps. The types of extraction solvents and adsorbents for the extraction procedure were optimized to achieve high recoveries and reduce coextractives in the final extracts. Due to significant matrix effects for all analytes (≤68.9% and ≥110.0%), matrix‐matched calibration curves were introduced for reliable quantification, exploring excellent linearity for the seven mycotoxins with coefficients of determination >0.9992. The method allowed high sensitivity with limit of detection in the range of 0.031–2.5 μg/kg and limit of quantitation in the range of 0.078–6.25 μg/kg, as well as satisfactory precision with relative standard deviations lower than 8%. Recovery rates were between 74.3 and 119.8% with relative standard deviations below 7.43%. The proposed method was successfully applied for 24 batches of P. multiflorum samples, and six samples were found to be positive with aflatoxin B1, B2, G1, or ochratoxin A. The method with significant advantages, including minimum analytical time, low time and solvent consumption, and high sensitivity, would be a preferred candidate for economic analysis of multiclass mycotoxins in complex matrices. 相似文献
992.
Bao Zhang Chunjuan Dong Qingmao Shang Yuan Cong Weijia Kong Pinglan Li 《Applied biochemistry and biotechnology》2013,171(8):2262-2272
Bacillus amyloliquefaciens K103 isolated from a lemon sample was used as a biocontrol agent to suppress Rhizoctonia solani Kühn and other fungal plant pathogens. Two antifungal compounds were purified from the culture broth using acid precipitation, gel permeation chromatography, and reversed-phase high-performance liquid chromatography. Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis indicated that the antifungal compounds were two isomers similar to bacillomycin L. One of the predominant active fractions was subjected to quadrupole time-of-flight mass spectrometry and amino acid analysis to determine its structural characteristics, revealing that the antifungal compound with a molecular mass of 1,034.5464 was identical to bacillomycin L. This is the second report of lemon microflora producing bacillomycin L or any antifungal compound, suppressing the growth of R. solani Kühn. Meanwhile, the study provided insights into the enormous potential of food microbial resources and bacillomycin L antibiotics in biological control and sustainable agriculture. 相似文献
993.
Lu Y Luo J Xu D Huang X Kong L 《Rapid communications in mass spectrometry : RCM》2008,22(16):2447-2452
High-performance liquid chromatography with an evaporative light scattering detector and electrospray ionization multistage tandem mass spectrometry (HPLC/ELSD/ESI-MS(n)) was used to identify spirostanol saponins in a saponin extract of Solanum torvum. The fragmentation behavior of saponins was studied using ESI-MS(1-3) in positive ion mode. The MS(n) spectra of the [M+H](+) ions provide structural information including aglycone type and the nature and sequence of sugars. The use of ELSD allowed the profiling of the nonchromophore-containing saponins in this plant. The MS analysis established in this study with known saponins was successfully applied to tentatively identify two new siprostanol glycosides, neosolaspigenin 6-O-beta-D-quinovopyranoside and solagenin 6-O-[beta-D-xylopyranosyl-(1 --> 3)-O-beta-D-quinovopyranoside]. 相似文献
994.
995.
Structural and Magnetic Properties of CoGen− (n=2–11) Clusters: Photoelectron Spectroscopy and Density Functional Calculations 下载免费PDF全文
Xiao‐Jiao Deng Dr. Xiang‐Yu Kong Dr. Xi‐Ling Xu Dr. Hong‐Guang Xu Prof. Dr. Wei‐Jun Zheng 《Chemphyschem》2014,15(18):3987-3993
A series of cobalt‐doped germanium clusters, CoGen?/0 (n=2–11), are investigated by using anion photoelectron spectroscopy combined with density functional theory calculations. For both anionic and neutral CoGen (n=2–11) clusters, the critical size of the transition from exo‐ to endohedral structures is n=9. Natural population analysis shows that there is electron transfer from the Gen framework to the Co atom at n=7–11 for both anionic and neutral CoGen clusters. The magnetic moments of the anionic and neutral CoGen clusters decrease to the lowest values at n=10 and 11. The transfer of electrons from the Gen framework to the Co atom and the minimization of the magnetic moments are related to the evolution of CoGen structures from exo‐ to endohedral. 相似文献
996.
In this study, the antibacterial effect and mode of Coptidis rhizoma on Escherichia coli was evaluated by microcalorimetry coupled with chemometric techniques. Using an isothermal microcalorimeter, the metabolic profiles of E. coli growth at 37 °C affected by 15 batches of C. rhizoma were measured. Through principal component analysis (PCA) on nine quantitative thermo-kinetic parameters obtained from the metabolic power-time profiles of E. coli, the antibacterial effects of C. rhizoma from various sources could be easily evaluated by analyzing the change of the two main thermo-kinetic parameters, growth rate constant k(2) and maximum heat-output power P(2)(m), in the second exponential phase of E. coli growth. Then, hierarchical clustering analysis (HCA) was carried out on the two parameters to distinguish those C. rhizoma samples in respect to their antibacterial effects. Clear results were obtained to show that all 15 C. rhizoma samples with different antibacterial effects could be successfully grouped in accordance with their origins. Ranked in decreasing order, the antibacterial mode of C. rhizoma samples that were from Sichuan province had the strongest antibacterial effects, followed by samples from Chongqing city and Hubei province. Our results revealed that the developed microcalorimetry with chemometric techniques had the potential perspective for evaluating the effect and mode of Coptidis rhizoma and other Chinese materia medicas. 相似文献
997.
Self-assembled Ge islands were grown on Si(100) substrate by Si2H6-Ge molecular beam epitaxy. After being subjected to chemical etching, it is found that the photoluminescence from the etched Ge islands became more intense and shifted to the higher-energy side compared to that of the as-deposited Ge islands. This behaviour was explained by the effect of chemical etching on the morphology of the Ge islands. Our results demonstrate that chemical etching can be a way to change the luminescence property of the as-deposited islands. 相似文献
998.
Chang Yi Kong Yuan Yuan Gu Masato Nakamura Toshitaka Funazukuri Seiichiro Kagei 《Fluid Phase Equilibria》2010
Binary diffusion coefficients, D12, of the metal acetylacetonates, palladium(II) acetylacetonate and cobalt(III) acetylacetonate, were measured from 308.2 to 343.2 K over the pressure range from 9 to 40 MPa at infinite dilution in supercritical carbon dioxide using the chromatographic impulse response method. The effects of pressure, temperature, density, and viscosity on D12 values were examined. It was observed that the D12 values of palladium(II) acetylacetonate and cobalt(III) acetylacetonate were larger than those of lipids with similar molecular weights, such as arachidonic acid and monoolein, respectively. Furthermore, the measured D12 data of each metal acetylacetonate were well correlated by the hydrodynamic equation D12/T as a function of carbon dioxide viscosity. 相似文献
999.
1000.
Lu Bai Xiaodong Wang Shengwen Kong Ying Song Xiaozhi He Yuehua Cong 《Liquid crystals》2019,46(4):503-511
A series of quaternary phosphonium salts based on ionic liquid-crystalline polymers which were synthesised by triphenylphosphine and brominated polysiloxanes containing cholesteryl mesogens. The chemical structures, liquid crystalline properties and antimicrobial performance of [ChP]Brs were investigated by a series of test methods. [ChP]Brs showed smectic A mesophase with a wide temperature range of liquid crystalline phase in the heating and cooling cycles. The glass transition temperature and clearing point temperature decreased with the increase of triphenylphosphine content. While the increase of phosphorus content lead to the increase of antibacterial properties of polymers. The liquid crystal polymer provides full spatial support for complete contact between phosphorus ions and bacteria, So that the quaternary phosphonium salt can be fully sterilised. 相似文献