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对来自不同地区的板蓝根粉末样品用X射线衍射傅立叶(Fourier)指纹图谱技术进行鉴定.由于不同产地的板蓝根样品的指纹图谱不同,因此,采用这一技术可对板蓝根样品作出区别和鉴定.试验结果表明该方法尚可应用于其他中药的鉴别. 相似文献
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色谱指纹图谱组合相似度的算法 总被引:1,自引:0,他引:1
色谱指纹图谱相似度是评价中药质量稳定性的有效手段之一,其中向量夹角余弦相似度应用最为广泛。但是当色谱峰面积分布范围宽时,夹角余弦对数据的差异响应不灵敏。以土茯苓色谱指纹图谱数据为实例证实了当两样本数据间比例相差较大时,夹角余弦相似度对共有峰和非共有峰响应的灵敏程度相差很大。组合相似度在共有峰的夹角余弦相似度基础上纳入了非共有峰的影响,分别计算非共有峰和共有峰对相似度的贡献,并以最大峰比例同态性为指标,确定非共有峰的合适权重。基于样本峰面积数据建立的组合相似度模型能灵敏地反映待测样本与参照样本内在成分的峰比例变化,适合衡量多个药材样本间的相似程度,已成为评价药材质量相似度的新方法。 相似文献
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建立了菌陈挥发油GC-MS指纹图谱,将正交投影算法用于不同样本中共有峰的提取,提高了共有峰的识别能力,降低了由于保留时间的漂移、质谱检索匹配度不高以及色谱峰重叠而引起的共有峰识别的难度.采用共有峰率、变异率及相似度等几个指标对4个不同产地的菌陈挥发油成分进行了评价,从共性、差异和整体性等多个方面全面表征菌陈挥发油的化学模式特征.结果表明,不同产地的菌陈挥发油成分大致相同,该指纹图谱可用于菌陈中挥发油成分的质量控制. 相似文献
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在恒温恒压条件下,以丙酮和样本中底物作为主要耗散物的不同成分的样本对非线性化学反应机理产生不同影响,从而引起反应体系电位-时间曲线形状不同变化为特征的B-Z化学振荡体系为例,就非线性化学指纹图谱原理进行了详细研究和讨论,并提出了计算非线性化学指纹图谱系统相似度的通用方法.利用系统相似度和欧氏距离、相关系数及夹角余弦对不同生产批次古汉养生精和18种其他样本的非线性化学指纹图谱的相似度进行了计算与分析.结果表明,相关系数和夹角余弦都不能用来作为评价非线性化指纹图谱相似度的指标.利用欧氏距离公式计算指纹图谱的非参数型相似度时,能正确反映指纹图谱的特征差异,但用其计算参数型相似度时,则有时不能正确反映样本非线性化学指纹图谱特征差异的相对程度.系统相似度能最真实反映样本指纹图谱之间差异程度,是4种相似度计算方法中最好的,可用于非线性化学指纹图谱相似度计算与评价.成功提出了一种经济、简便、易行和有效的鉴别样本真伪与评价其质量的科学方法. 相似文献
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该文以研究指纹图谱在绿茶等级判别方面应用的可行性为目的。以信阳毛尖茶为研究对象,以茶汤香气成分为研究目标,采用顶空固相微萃取与气相色谱-质谱联用技术,筛选其香气特征成分,建立不同等级信阳毛尖茶香气成分GC-MS指纹图谱。发现运用判别分析法可以对2个系列7个等级41个信阳毛尖茶样进行很好的等级区分;通过不同等级色谱指纹图谱的相似度计算发现,相似度与茶样等级之间具有较好的相关性,尤其是对于品质较好的茶样,这种相关性更好。表明运用判别分析法和相似度计算方法能够反映绿茶等级之间的差异性,且基于相似度评价的方法具有客观量化的特征。 相似文献
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高效液相色谱法分离/蒸发光散射和紫外检测法测定天麻中天麻甙含量 总被引:2,自引:0,他引:2
天麻(Gastrodia elata Blume)系兰科多年生寄生植物,用于治疗头错、眩晕、肢体麻木等症,冯孝章和周俊等分离并鉴定出天麻的活性成分有天麻甙(对羟甲基苯β-D-吡喃葡萄糖式,亦称天麻素)、天麻甙元(对羟基苯甲醇)等,其中天麻甙为主要成分,一些药理实验也证实了这一点,在测定天麻甙含量的方法中,采用高效液相色谱法9HPLC)最多,正相PHLC和反相HPLC都可用于天麻及其占天麻甙的分离,-通常采用紫外检测法,检测波长在220nm或270nm处。 相似文献
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The thermotropic behaviour of sodium oleate (NaOl) has been studied in the temperature range 10–125°C by using Fourier transform-Raman spectroscopy, X-ray diffraction and differential scanning calorimetry (DSC). The temperature dependence of conformationally sensitive bands in the CH2 stretching (2800–2900 cm−1), C–C stretching (1050–1150 cm−1) and CH3 rocking region (830–900 cm−1) has been used to characterize the order/disorder behaviour of alkyl chains. It is found that in phase I, NaOl exhibits the crystalline ordered lamellar structure with a repeat period of 4.51 nm. The first broad peak in the DSC trace is due to superposition of two transitions (phase I to phase II and phase II to phase III), therefore, it is not possible to determine the lamellar structure of phase II. This broad transition from phase I to phase III is associated with the melting of methyl-sided chains and increase in gauche conformers in carboxylate-sided chains. Finally, NaOl undergoes a transition from crystalline to a liquid crystalline phase IV, which is associated with the melting of the carboxylate-sided chain. 相似文献
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大黄游离羟基蒽醌的TG—DTA和XRD谱图特征分析 总被引:1,自引:0,他引:1
中药大黄属蓼科植物,性寒味苦,是中医临床常用药物,具有攻坚破积、活血化瘀、泻火凉血、清热解毒及抗菌、抗炎、调节免疫、抗肿瘤、止血和保健等作用[1]. 相似文献
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J. Kikuma M. Tsunashima S. Matsuno K. Matsui 《Journal of solid state chemistry》2011,184(8):2066-2074
Hydrothermal synthesis process of tobermorite (5CaO·6SiO2·5H2O) has been investigated by in-situ X-ray diffraction using high-energy X-rays from a synchrotron radiation source in combination with a purpose-build autoclave cell. Dissolution rates of quartz were largely affected by its particle size distribution in the starting mixtures. However, the composition (Ca/Si) of non-crystalline C-S-H at the start of tobermorite formation was identical regardless of the quartz dissolution rate. An effect of water-to-solid ratio (w/s) was investigated for samples using fine particle quartz. Tobermorite did not occur with w/s of 1.7 but occurred with w/s higher than 3.0. Surprisingly, however, the dissolution curves of quartz were nearly identical for all samples with w/s from 1.7 to 9, indicating that the dissolution rate is predominated by surface area. Possible reaction mechanism for tobermorite formation will be discussed in terms of Ca and/or silicate ion concentration in the liquid phase and distribution of Ca/Si in non-crystalline C-S-H. 相似文献
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Foresti E Gazzano M Gualtieri AF Lesci IG Lunelli B Pecchini G Renna E Roveri N 《Analytical and bioanalytical chemistry》2003,376(5):653-658
A new analytical method for the determination of low levels (0.01–1 wt%) of free fibres of chrysotile in contaminated clayey, sandy and sandy-organic soils is described. The detection limit of 0.01 wt% is reached with an enrichment of free fibres of chrysotile in the sample using a standard laboratory elutriator for sedimentation analysis. The chrysotile quantitative determination is performed both by X-ray powder diffraction, using the internal standard and reference intensity ratio methods, and by Fourier-transform infrared absorption spectroscopy. The procedure can be successfully applied to different soils after removal, by a thermal treatment, of the matrix components which can interfere. This straightforward method fulfils the request of public institutions and private companies for an appropriate quantitative determination of chrysotile-free fibres in contaminated soils. 相似文献
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Mitsuhiro Kanakubo Takafumi Aizawa Hiroshi Nanjo Yasuo Kameda Yuko Amo Takeshi Usuki 《Fluid Phase Equilibria》2010
X-ray diffraction measurements for the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4], mixed with CO2 were carried out at high pressures using our developed polymer cell. The intermolecular distribution functions obtained for [BMIM][BF4]–CO2 mixtures showed that CO2 molecules are preferentially solvated to the [BF4]− anion. The similar preferential solvation was previously observed in analogous 1-btuyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], with a different anion, which is in harmony with the present results in [BMIM][BF4]–CO2. 相似文献
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B. Fouconnier L. Komunjer M. Ollivon P. Lesieur G. Keller D. Clausse 《Fluid Phase Equilibria》2006,250(1-2):76-82
Differential scanning calorimetry (DSC) and time-resolved synchrotron X-ray diffraction as a function of temperature (XRDT) were combined in a novel way in order to study conditions of formation and the amount of gas clathrate formed in dispersed systems. The formation and dissociation of trichlorofluoromethane hydrate CCl3F·(H2O)17 in a water-in-oil emulsion were followed by using these combined techniques. An emulsion containing 3 wt.% NaCl was submitted to a cooling and heating cycle between 20 and −50 °C. During cooling, a single exothermic peak at −43 °C, found in DCS thermograms was assigned to the freezing of under-cooled water droplets; however, no noticeable signal related to hydrate crystallisation was detected. Conversely, during subsequent heating, the progressive melting of ice was followed by an endothermic signal indicative of hydrate decomposition. From X-ray diffraction performed on an emulsion sample, it was possible to identify the exact condition of CCl3F·(H2O)17 formation. XRDT diffraction patterns clearly demonstrated that only ice crystallised in the aqueous droplets during cooling and that the hydrate only formed during heating simultaneously with melting of ice. From the solid–liquid phase diagrams of systems H2ONaCl and CCl3FH2ONaCl and from the DSC and XRDT experiments, the composition of the droplets was deduced. The upper limit of the amount of hydrate that could form in the system was calculated. 相似文献
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Eugene Y. Cheung Kenneth D.M. Harris Barbara R. Conway 《Journal of solid state chemistry》2007,180(3):1068-1075
We report the formation and structural properties of co-crystals containing gemfibrozil and hydroxy derivatives of t-butylamine H2NC(CH3)3−n(CH2OH)n, with n=0, 1, 2 and 3. In each case, a 1:1 co-crystal is formed, with transfer of a proton from the carboxylic acid group of gemfibrozil to the amino group of the t-butylamine derivative. All of the co-crystal materials prepared are polycrystalline powders, and do not contain single crystals of suitable size and/or quality for single crystal X-ray diffraction studies. Structure determination of these materials has been carried out directly from powder X-ray diffraction data, using the direct-space Genetic Algorithm technique for structure solution followed by Rietveld refinement. The structural chemistry of this series of co-crystal materials reveals well-defined structural trends within the first three members of the family (n=0, 1, 2), but significantly contrasting structural properties for the member with n=3. 相似文献
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The effect of a self-assembly nucleating agent, N,N′,N″-tricyclohexyl-1,3,5-benzenetricarboxylamide (BTCA), on the crystallization behavior of poly(lactic acid) (PLA) was probed by time-resolved Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). The vibrational changes associated with inter- and intra-chain interactions during crystallization were monitored. In the initial period of crystallization, the order of intensity changes is as follows: 1458 cm−1 > 1210 cm−1 » 921 cm−1, 1458 cm−1 ∼ 1210 cm−1 > 921 cm−1, and 1458 cm−1 ∼ 1210 cm−1 ∼ 921 cm−1 for neat PLA, PLAs containing 0.1 wt% and 0.3 wt% BTCA, respectively. This indicates that BTCA can accelerate both the formation of skeletal conformational-ordered structure and, especially, the 103 helix one. The incorporation of BTCA changes the crystallization mechanism but has no impact on the crystal form of PLA. 相似文献
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Maxim Avdeev Sergey Yakovlev Aleksey A. Yaremchenko Vladislav V. Kharton 《Journal of solid state chemistry》2007,180(12):3535-3544
The results of in situ high-temperature X-ray and neutron powder diffraction experiments reconcile inconsistencies in previous reports on the symmetry of high-temperature phases of SrAl2O4. The material undergoes two reversible phase transitions and at 680 and 860 °C, respectively, and the latter one is experimentally observed and characterized for the first time. The higher symmetry above the transition is gained by disordering off-center split site of oxygen atoms around trigonal axis rather than by unbending Al–O–Al angle to the ideal value 180°. The analysis of the literature suggests that it is a common feature of the P6322 phases of stuffed tridymites. 相似文献