微波及超声法提取苦丁茶中熊果酸的对比研究

采用微波法和超声法辅助提取苦丁茶中的熊果酸。建立苦丁茶中熊果酸的分析测定方法,通过单因素及正交实验确定较佳的提取方法——微波提取,最佳提取工艺条件为:乙醇浓度85%,粒径100目,微波提取时间150 s,料液比1:30,此时的熊果酸得率为11.824%。     

蛇床子挥发性成分的GC/MS分析

用超临界二氧化碳和水蒸气蒸馏法提取蛇床子挥发性化学成分,采用毛细管气相色谱-质谱联用技术对2种提取方法所提取的挥发性成分进行分析鉴定。共鉴定出48个挥发性化合物,从水蒸气蒸馏提取物中鉴定出31个化学成分,从超临界二氧化碳提取物中鉴定出21个化学成分,超临界二氧化碳提取方法对蛇床子挥发性成分的提取具有较高的选择性。从蛇床子中检测到蛇床子素、欧前胡素、异虎尔草素、佛手内酯、花椒毒素和花椒毒酚6个香豆素类化合物,并应用质谱学规律对蛇床子中的有效成分蛇床子素的结构进行鉴定和讨论。     

微波辅助法提取红景天有效成分的研究

目的：优化微波辅助法提取红景天有效成分的工艺。方法：采用单因素和正交实验设计,以红景天苷的含量为评价指标,对红景天有效成分进行微波辅助法提取。结果：其最佳工艺条件为：20倍量的水浸泡过40目药粉30min后用中低火微波处理40s,然后在70℃提取10min,提取次数2次。该条件下红景天苷含量达到4．43mg／g。结论该法对红景天有效成分提取率高、成本低,值得推广使用。     

星点设计—效应面优化法在中药提取中的应用

在科学实验中,星点设计—效应面优化法是同时考察多个因素对结果的影响时常用的实验设计和优化方法,具有预测性好、实验简单、高效等特点,可以很好地应用在中药有效成分提取的研究领域。现介绍了星点设计—效应面优化法的基本原理和操作步骤,综述了该方法在中药有效成分提取过程优化中的应用。     

天然产物中有效成分不同提取方法的研究与分析

天然产物中的有效成分活性明显,是其发挥疗效的关键因素,但有效成分在天然产物中的含量一般都较低,因此选择正确的提取方法至关重要。随着科学技术的进步,不断涌现出了提取天然产物有效成分的新方法、新工艺。现综述了近年来天然产物中黄酮、多糖、挥发油、生物碱与萜类的提取方法及特点,并对各有效成分的不同提取方法进行了比较与分析,以期为天然产物有效成分的提取提供参考。     

熊果酸的提取、分离及分析方法的研究进展探析

综述了近年来熊果酸的提取、分离纯化及分析方法的研究进展,以期为熊果酸的研究发展提供参考借鉴。     

外场微波辅助提取技术在植物有效成分提取中的应用

介绍了微波辅助萃取方法的原理、特点、工艺过程以及设备,并列举了近5年来在植物有效成分提取过程中的应用。     

高效液相色谱—质谱联用法在分析检测中的运用分析

介绍了高效液相色谱-质谱联用技术法的技术优点及其分析方法,并综述了该技术在中草药有效成分提取分离等领域中的研究与应用。     

高效液相色谱法测定蜂胶中的黄酮成分

蜂胶是一种纯天然物质,具有生理和药理活性。本文提出一种分析蜂胶及其制品中总黄酮成分的高效液相色谱法(HPLC)。该法采用甲醇回流提取其有效成分,能同时分离测定9种黄酮成分。回收率96.7％,变质系数4.1％。     

一种多级组合连续逆流超声提取机组

介绍一种用于中药及天然植物有效成分提取的多级组合连续逆流超声提取设备。其突出特点是具有应用柔性，适应多品种大规模提取生产使用需求。     

不同花色映山红花中熊果酸和齐墩果酸的含量比较

结合超声技术提取不同花色映山红花中熊果酸和齐墩果酸,建立RP—HPLC法测定其含量。采用KromasilC18色谱柱（250mm×4．6mm,5μm）,流动相为甲醇-0．2％磷酸水溶液（88：12）,光电二极管阵列检测器,检测波长210nm,流速0．8mL／min,柱温30℃。以保留时间和紫外光谱对分离出的组分予以定性确证,用峰面积进行定量。组分的质量浓度与其峰面积在一定的范围内呈现良好的线性关系,相关系数均为0．9999,熊果酸进样量在0．443～7．088μg,齐墩果酸进样量在0．247～3．952μg时呈现良好的线性关系,平均加样回收率分别为98．53％和98．36％,RSD分别为1．3％和1．5％（n=5）。方法灵敏、准确,重现性好,可用于不同花色映山红花中熊果酸和齐墩果酸含量的测定。     

Morphoanatomical and phytochemical studies of Salvia lachnostachys (Lamiaceae)

Salvia lachnostachys Benth., Lamiaceae, is a endemic species from southern Brazil. The essential oil of its leaves and flowers is mainly constituted by aliphatic compounds, such as dodecanoic acid, with sesquiterpenes as minor constituents. This work evaluated the morphology, anatomy, microchemistry, and phytochemistry of S. lachnostachys to provide advanced knowledge of Brazilian plants with medicinal potential. Light and scanning electron microscopy techniques were used in the anatomical and microchemical studies. Compounds were isolated by chromatographic techniques, identified by analysis of their NMR spectra and compared with published data. S. lachnostachys can be distinguished from other related species mainly by its petiolate leaves, terminal inflorescence, persistent bracts, and villous‐glandular corolla. The stem and leaves of S. lachnostachys display anatomical characteristics common to the family Lamiaceae. However, this species can be distinguished from other family members by the morphology and the presence of eglandular and glandular trichomes, as well as the organization of the vascular bundles of the petiole. The phytochemical results revealed that S. lacnostachys produces oleanolic and ursolic acids in addition to the diterpene fruticuline A, which is a rare compound, previously found only in Salvia fruticulosa Benth. and S. corrugata Vahl. Ursolic and oleanolic acids are bioactive triterpenes that exhibit antiatherosclerotic, anticancer, antihypertensive, antinflammatory, antileukemic, antimutagenic, antioxidant, antiproliferative, and antiviral activities, and fruticuline A has antibacterial activity. Microsc. Res. Tech. © 2012 Wiley Periodicals, Inc.     

Investigation of foreign substances in food

Scanning electron microscopy (SEM) together with energy-dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to investigate foreign substances from seven categories of foreign substances in food. (1) Naturally occurring foreign substances--Using FTIR, a foreign substance was identified as a natural resin probably from the product. (2) Foreign substances introduced during food processing. Scanning electron microscopy-EDS was used to identify a foreign material found on surf clams as calcium phosphate from a product/ingredient interaction. Using SEM-EDS, a crystalline material in a meat product was identified as calcium salts of chloride and phosphate. Fourier transform infrared spectroscopy was used to identify foreign material that clogged an aerosol valve as chipboard. Using SEM-EDS, the metal in the heel of a glass bottle was identified as copper sulfide-containing metal inclusion. (3) Insects, reptiles, and rodents--Scanning electron microscopy was used to determine that a mouse found in food was not processed with the food, but entered the container after it left the factory. (4) Glass fragments--Glass from various sources can be distinguished from one another using SEM-EDS either by the level of the major elements in glass or by the presence of elements in one glass, but not in another. (5) Glass-like particles--Using SEM-EDS, glass-like particles found on beets were determined to be a fatty acid. (6) Metal foreign objects--Using SEM-EDS, metals from a variety of sources can be easily distinguished. For example, a tin-soldered container can be distinguished from a lead-soldered can. Using SEM-EDS, the metal fiber found on the bottom of a two-piece can likely enter the can during the final stage of the manufacture of the drawn and ironed food can. (7) Drug capsule identification--Fourier transform infrared spectroscopy was used to determine that a pill found in food was ibuprofen.     

Functional mechanism of formation of friction polymer with dihydroxydocosanoic acid

The results of wear tests with a four-ball machine showed that dihydroxydocosanoic acid has good antiwear properties, comparatively approaching those of zinc dialkyldithiophosphate (ZDDP): the four-ball wear-scar diameters, d 30 min/294 N, with dihydroxydocosanoic acid, ZDDP, and 400 neutral base oil are 0.36, 0.35, and 0.62 mm, respectively. In order of effectiveness the antiwear ability of the C₂₂ acids is: 13,14-dihydroxydo-cosanoic acid (I) 13(14)-mono-hydroxydocosanoic acid (II) docosanoic acid (III), showing that their antiwear properties are remarkably improved after introduction of the hydroxy group into fatty acids. Work on dihydroxy acid as an antiwear agent is not much reported in the literature up to now. In the present work, it was verified with infrared spectroscopy that polyester is formed on the rubbing surfaces with I and II by tribochemical reaction. An oxygen-rich protective film on the rubbing surfaces was identified with Auger Electron Spectroscopy analysis. These results are identical to the high oxygen-containing polyester film shown by IR analysis. It is preliminarily confirmed that the functional antiwear mechanism is, principally, the formation of a polymeric friction film on the rubbing surfaces.     

二羟基廿二酸的抗磨作用机理

四球机磨损试验表明,二羟基廿二酸具有良好的抗磨性,与传统的抗磨剂二烷基二硫代磷酸锌(ZDDP)比较接近。C22酸的抗磨性优劣次序为13,14－二羟基廿二酸(DHDA)＞13(14)－羟基廿二酸(MHDA) ＞廿二酸(DA),表明羟基的引入能显著地提高基础油的抗磨性。红外光谱说明DHDA和MHDA可能与摩擦表面起摩擦化学反应形成聚酯。俄歇电子能谱分析揭示DHDA在摩擦表面形成富氧保护膜,这与IR分析结果二羟基廿二酸能形成含氧较高的网状聚酯膜相一致。初步结果说明了二羟基廿二酸通过形成摩擦聚合物膜而起抗磨作用。     

A spectroscopic study of a copper surface under boundary lubrication: I. Chemisorbed stearic acid multilayers

The thickness of chemisorbed stearic acid films on copper surfaces was deduced by Fourier transform infrared (FTIR) spectroscopy and Auger electron spectroscopy (AES). The chemisorption was detected by FTIR from the carboxyl (COO) asymmetric stretching band at 1585 cm⁻¹. Multilayer growth was observed by monitoring the intensity increase in the asymmetric CH₂ stretching mode at 2915 cm⁻¹. The growth of the chemisorbed layer was found to depend on the concentration of the stearic acid/hexadecane solution. The chemisorption kinetic profile had a step-function due to the change in the number of layers. High carbon concentration in Auger spectroscopic characterisation indicated that the surface was coated with a stearic acid film. AES depth profiling analysis supports this step-function model and agrees well with the FTIR results.     

Near-field photothermal microspectroscopy for adult stem-cell identification and characterization

The identification of stem cells in adult tissue is a challenging problem in biomedicine. Currently, stem cells are identified by individual epitopes, which are generally tissue specific. The discovery of a stem-cell marker common to other adult tissue types could open avenues in the development of therapeutic stem-cell strategies. We report the use of the novel technique of Fourier transform infrared near-field photothermal microspectroscopy (FTIR–PTMS) for the characterization of stem cells, transit amplifying (TA) cells and terminally differentiated (TD) cells in the corneal epithelium. Principal component analysis (PCA) data demonstrate excellent discrimination of cell type by spectra. PCA in combination with linear discriminant analysis (PCA–LDA) shows that FTIR–PTMS very effectively discriminates between the three cell populations. Statistically significant differences above the 99% confidence level between IR spectra from stem cells and TA cells suggest that nucleic acid conformational changes are an important component of the differences between spectral data from the two cell types. FTIR–PTMS is a new addition to existing spectroscopy methods based on the concept of interfacing a conventional FTIR spectrometer with an atomic force microscope equipped with a near-field thermal sensing probe. FTIR-PTMS spectroscopy currently has spatial resolution that is similar to that of diffraction-limited optical detection FTIR spectroscopy techniques, but as a near-field probing technique has considerable potential for further improvement. Our work also suggests that FTIR–PTMS is potentially more sensitive than synchrotron radiation FTIR spectroscopy for some applications. Microspectroscopy techniques like FTIR–PTMS provide information about the entire molecular composition of cells, in contrast to epitope recognition that only considers the presence or absence of individual molecules. Our results with FTIR–PTMS on corneal stem cells are promising for the potential development of an IR spectral fingerprint for stem cells.     

Investigation of tribo-chemistry by means of stable isotopic tracers: Mechanism for durability of monomolecular boundary film

A monomolecular film of octadecanoic acid on a Si(1 0 0) surface was prepared using a computer-controlled Langmuir trough. The tribological properties were acquired by a ball-on-flat type tribo-tester under reciprocating motion. Considerable effects of ball material on lifetime for low friction were observed; a glass ball was excellent while a steel ball was poor. The rubbed surfaces on ball and flat were studied by time-of-flight secondary ion mass spectroscopy. Transfer of the carboxylic acid and silicon onto the ball surface from the flat specimen was found. The role of the transferred acid that prolongs the lifetime of low friction was proposed. It should be emphasized that deuterium-labeled carboxylic acid makes the target of TOF-SIMS analysis clear.     

Electrochemical study of the interaction between fatty acid and oxidized copper

Boundary lubrication involving reactions between the metal oxide layers and adsorbed polar species has been reported by several authors. In this study, the effect of an oxide layer on the mechanism of boundary lubrication during copper wire drawing was examined by electrochemical and surface analysis techniques. The minimum oxide thickness to initiate chemical and electrochemical reactions, and the oxide growth rate were determined by electrochemical methods. The oxide formed prior to chemical reaction with a fatty acid during boundary lubrication, and the chemical products were analyzed by electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES). The properties of adsorbed layers were characterized by AC impedance spectroscopy. Optimum boundary lubrication can only be achieved during copper deformation, if the oxide thickness exceeds the minimum thickness of 60 Å and is cornposed of cuprous oxide.     

Surface Films and Soluble Degradation Products Formed in a PFPAE Fluid and Their Implications to the Wear of Steel

The soluble degradation products were generated in a linear perfluoropolyalkylether (PFPAE) fluid in boundary lubrication. Perfluoropolyalkylether carboxylic acid species were found in the residual fluids from the sliding tests by vibration spectroscopy. Surface-bound organic and inorganic reaction products were identified by vibration microspectroscopy with a grazing angle objective attachment and X-ray photoelectron spectroscopy (XPS), respectively. Inorganic surface films were found to be composed primarily of FeF₃. A monodentate perfluorocarboxylate surface species was found on the sliding surfaces in 50° and 100°C tests but not found in 150°C tests. The higher friction and wear in 150°C tests as compared to 50° and 100°C tests were attributed to the absence of the perfluorocarboxylate species over the sliding surfaces at high temperatures.