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1.
《Comptes Rendus Chimie》2016,19(6):754-765
Rosemary (Rosmarinus officinalis L.) is a perennial herb with an intensive aromatic flavor. Its most important chemical constituents are essential oils (e.g., 1,8-cineole and camphor) and antioxidants (e.g., carnosic acid and rosmarinic acid). The common methods to extract the essential oil of rosemary are steam or hydro distillation. The aim of this work is to investigate the residual antioxidants after hydro distillation, especially rosmarinic acid and carnosic acid. For this purpose, the hydro distillation water residues were analyzed by HPLC-UV. Moreover, the influence of the extraction duration on the concentration of the antioxidants was investigated. Also, the residual amount of these compounds in the leaves was examined. The total antioxidant activity of the extracts and of the pure compounds was determined by DPPH assays. It is shown that after 2.5 h of hydro distillation the amount of rosmarinic acid and the antioxidant activity in the water residue reaches a maximum value. In addition, the yield and the quality of the essential oil were investigated to draw a comparison between steam and hydro distillations of Moroccan rosemary leaves.  相似文献   
2.
杨新林 《高分子科学》2012,30(3):359-369
Tri-layer CdS/SiO2/polymer hybrid nanospheres were synthesized by distillation precipitation polymerization of either ethyleneglycol dimethacrylate(EGDMA) or EGDMA together with comonomers having different functional groups, such as methacrylic acid,4-vinylpyridine and 2-hydroxyethylmethacrylate,in the presence of 3-(methacryloxy)propyl trimefhoxysilane(MPS)-modified CdS/SiO2 nanoparticles as seeds in acetonitrile with 2,2’-azobisisobutyronitrile(AIBN) as initiator.In this approach,MPS-modified inorganic seeds were prepared by the modification of CdS/SiO2 nanoparticles via the self-condensation reaction between the hydroxyl groups of sinaols,in which the CdS/SiO-2 nanoparticles were afforded by a reverse microemulsion technique for the synthesis of CdS core nanoparticles with the subsequent coating of silica layer. The polymer shell-layers encapsulated over the MPS-modified CdS/SiO2 inorganic seeds via the efficient capture of the monomers and oligomers from the solution with the aid of the vinyl groups incorporated by the MPS modification,in which the polymer shell-thickness and functional groups including carboxyl,pyridyl and hydroxyl,were facilely controlled by the feed of EGDMA as well as the types of comonomers used for the polymerization.These nanospheres were characterized by transmission electron microscopy(TEM),Fourier-transform infrared spectroscopy(FT-IR),thermogravimetric analysis (TGA),fluorescence spectroscopy and zeta potential.  相似文献   
3.
高含量锗物料中锗的滴定法测定   总被引:4,自引:0,他引:4  
从碘酸钾容量法测定高含量锗物料中锗量的关键步骤蒸馏分离入手,分析了方法误差的原因,推出了一套设计合理、无泄漏、易于操作的蒸馏装置,使用该蒸馏装置蒸馏分离效果好,标准回收率高,测定结果精密高,具有推广价值。  相似文献   
4.
The analysis of complex fluids such as crude oils, fuels, vegetable oils and mixed waste streams poses significant challenges arising primarily from the multiplicity of components, the different properties of the components (polarity, polarizability, etc.) and matrix properties. We have recently introduced an analytical strategy that simplifies many of these analyses, and provides the added potential of linking compositional information with physical property information. This aspect can be used to facilitate equation of state development for the complex fluids. In addition to chemical characterization, the approach provides the ability to calculate thermodynamic properties for such complex heterogeneous streams. The technique is based on the advanced distillation curve (ADC) metrology, which separates a complex fluid by distillation into fractions that are sampled, and for which thermodynamically consistent temperatures are measured at atmospheric pressure. The collected sample fractions can be analyzed by any method that is appropriate. The analytical methods we have applied include gas chromatography (with flame ionization, mass spectrometric and sulfur chemiluminescence detection), thin layer chromatography, FTIR, corrosivity analysis, neutron activation analysis and cold neutron prompt gamma activation analysis. By far, the most widely used analytical technique we have used with the ADC is gas chromatography. This has enabled us to study finished fuels (gasoline, diesel fuels, aviation fuels, rocket propellants), crude oils (including a crude oil made from swine manure) and waste oils streams (used automotive and transformer oils). In this special issue of the Journal of Chromatography, specifically dedicated to extraction technologies, we describe the essential features of the advanced distillation curve metrology as an analytical strategy for complex fluids.  相似文献   
5.
GC-MS分析香独活挥发油成分   总被引:4,自引:0,他引:4  
采用水蒸气蒸馏法从香独活中提取挥发油,用气相色谱一质谱联用技术(GC-Ms)检测并分析其化学成分,用归一化法测定其相对含量,结果鉴定出39个成分.占挥发油总成分的83.10%。其中主要成分为4-甲氧基-6-(2-丙烯基)-1.2-亚甲二氧基苯和1-[3-甲氧基-5-羟基苯]-1,2.3,4-四甲基-异喹啉。  相似文献   
6.
Tri-layer magnetite/silica/poly(divinylbenzene) (Fe3O4/SiO2/PDVB) core-shell hybrid microspheres were prepared by distillation precipitation polymerization of divinylbenzene (DVB) in the presence of magnetite/3-(methacryloxyl)propyl trimethoxysilane (MPS) modified silica core-shell particles as seeds. The polymerization of DVB was performed in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator to coat magnetite/MPS-modified silica particles through the capture of DVB oligomers with the aid of vinyl groups on the surface of inorganic seeds in absence of any stabilizer or surfactant. Other magnetite/silica/polymer tri-layer hybrid particles, such as magnetite/silica/poly(ethyleneglycol dimethacrylate) (Fe3O4/SiO2/PEGDMA) and magnetite/silica/poly(ethyleneglycol dimethacrylate-co-methacrylic acid) (Fe3O4/SiO2/P(EGDMA-co-MAA)) with various polarity and functionality, were also prepared by this procedure. Magnetite/silica/poly(N,N′-methylenebisacrylamide-co-methacrylic acid) (Fe3O4/SiO2/P(MBAAm-co-MAA)) were synthesized with unmodified magnetite/silica particles as seeds. The resultant tri-layer hybrid particles were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), dynamic light scattering, and vibrating sample magnetometer (VSM).  相似文献   
7.
讨论了用共沸蒸馏法浓缩处理水、土壤、固废样品或其萃取液中不易吹除、具挥发性、且易溶于水的非卤代挥发性有机物,并用气相色谱质谱联用仪定性定量的方法.  相似文献   
8.
对于氨水吸收式制冷的精馏过程,其稳态传热传质平衡模型一旦破坏,精馏效果会迅速恶化。文中以筛板式精馏塔为研究对象,人为控制精馏过程塔板在冲塔和淹塔两种液泛工况下,分析了精馏段和整机性能。结果表明,发生液泛时,精馏塔的精馏操作和整机性能完全破坏。  相似文献   
9.
提出了用催化极谱法测定复杂物料中微量砷的含量。选择测定的溶液介质中含碲(Ⅳ)硫酸溶液5mL和150g.L-1碘化钾溶液5mL。仪器扫描速率为250mV.s-1,并采用二阶导数测定。试样(0.01~1.0g)用氯酸钾0.5g、氢氟酸5滴、硝酸5~10mL溶解,用蒸馏法分离其中的砷。砷的质量浓度在0.4mg·L-1以内与相应的峰电流呈线性关系。按此方法测定了12个矿样中砷含量,其测定值与已知值相符。方法的回收率在97%~100%之间,相对标准偏差(n=6)在2.3%~7.2%之间。  相似文献   
10.
An integrated microfluidic distillation system is proposed for separating a mixed ethanol-methanol-water solution into its constituent components. The microfluidic chip is fabricated using a CO2 laser system and comprises a serpentine channel, a boiling zone, a heating zone, and a cooled collection chamber filled with de-ionized (DI) water. In the proposed device, the ethanol-methanol-water solution is injected into the microfluidic chip and driven through the serpentine channel and into the collection chamber by means of a nitrogen carrier gas. Following the distillation process, the ethanol-methanol vapor flows into the collection chamber and condenses into the DI water. The resulting solution is removed from the collection tank and reacted with a mixed indicator. Finally, the methanol concentration is inversely derived from the absorbance measurements obtained using a spectrophotometer. The experimental results show the proposed microfluidic system achieves an average methanol distillation efficiency of 97%. The practicality of the proposed device is demonstrated by detecting the methanol concentrations of two commercial fruit wines. It is shown that the measured concentration values deviate by no more than 3% from those obtained using a conventional bench top system.  相似文献   
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