基于信息融合的中药多元色谱指纹图谱相似性计算方法

摘要用信息融合算法合并多张色谱指纹图谱, 解决中药多元指纹图谱相似性评价难题, 提出一种多元色谱指纹图谱相似度计算方法. 用该方法先对各单元指纹图谱进行串行或并行象素级信息融合, 再对融合了各指纹峰信息的多元色谱指纹图谱进行相似度评价. 计算机仿真和复方丹参滴丸多元HPLC指纹图谱应用结果表明, 该法能够评价中药多元色谱指纹图谱相似度, 定量表征中成药产品批次间质量波动情况.     

大黄酸键合硅胶固定相的简便制备及色谱性能评价

以大黄酸为原料,γ-氨丙基三乙氧基硅烷(KH-550)为偶联剂,简便制备了一种新型羧基键合硅胶固定相(RBSP),并用红外光谱、热重分析及元素分析对其结构进行表征.考察了流动相中甲醇含量对键合固定相色谱性能的影响,并以含酸性、中性和碱性化合物的混合物为溶质,评价了RBSP的色谱性能.以甲醇-水为流动相,用C18柱作参比,研究了该键合硅胶作为HPLC固定相对两种大豆异黄酮化合物和几种生物碱基的分离,并对其色谱分离机理进行了初步探讨.实验结果表明,该固定相(RBSP)具有较好的反相色谱性能,同时由于键合相中含有酚羟基及酰胺基团,能为多种溶质提供作用位点,对极性化合物的分离具有明显优势,且分离速度快,可有效用于极性化合物的分离分析.     

Catalysts Based on Fiberglass Supports: I. Physicochemical Properties of Silica Fiberglass Supports

The physicochemical properties and structure of supports prepared by leaching soda–silica fiberglass materials were studied using a set of physicochemical techniques (BET; IR spectroscopy; transmission electron microscopy; and ²⁹Si, ²³Na, ²⁷Al, ¹³³Cs, and ¹²⁹Xe (of adsorbed molecules) NMR spectroscopy). A matrix that corresponded in chemical composition to SiO₂was formed at high degrees of leaching; however, it was considerably different from ordinary silica gels in properties. The structure and properties of this matrix are most adequately described by the model of a pseudolayer intercalation structure, which includes alternating layers of several silicon–oxygen tetrahedrons separated by narrow (<4 Å) cavities. Considerable amounts of OH groups (5000 mol/g) are contained in these cavities, and these OH groups are different from the surface hydroxyl groups of ordinary globular silica. Although the interlayer spaces are small, comparatively bulky cations can be intercalated into them.     

Effect of Variant Counterions on Stability and Particle Size of Silica Sol

The effects of variant counterions with ionic strength of 0.05, 0.10, 0.20 and 0.25 mol·kg^-1 on the stability and particle size of silica sols have been studied using the traditional methods of Ubbelohde viscosity measurement, TEM and titration respectively, finding that the stability and particle size of the silica sols are all concerned with the acidic, positively electric properties and the sizes of the counterions, as well as the attraction between the counterions and surface silicon hydroxyl groups of the silica sols. The small positively charged counterions lead to the decrease in particle sizes, making the silica sol the most stable. But the larger weakly acidic counterions can restrict the particle sizes of the silica sols and easily make the sols coagulate. It was also found that there existed a linear relationship between log r and log η, which has not ever been reported. The effect of temperature on the stability and particle sizes was also discussed.     

基于超大孔聚合物微球的混合色谱模式层析介质的制备

以甲基丙烯酸缩水甘油酯与乙二醇二甲基丙烯酸酯共聚的超大孔聚合物微球为基质,采用聚乙烯亚胺和丁基缩水甘油醚先后衍生微球的表面,制备成兼具阴离子交换与疏水相互作用的混合色谱模式层析介质。考察离子交换基团、疏水配基密度对蛋白载量、回收率的影响,结果表明,在离子交换容量0.2~0.5 mol/mL范围内,随着介质离子交换容量的增大,蛋白载量及回收率均呈增加趋势,蛋白载量最高值达40 mg/mL,回收率大于90%。当疏水配基的密度大于0.03 mol/mL时,介质开始表现疏水相互作用。此超大孔混合模式色谱介质在大于2000 cm/h 的流速下依然能保持低于2 MPa 的柱背压,同时在高流速下(2880 cm/h)纯化人血清中的抗体应用中表现良好的分辨率。此介质在高通量分离纯化应用方面具有巨大潜力。     

Effect of Particle Size on Rate of Coalescence of Silica Nanoparticles

In high temperature processes, at high concentrations, aerosol particles grow by collisions and coalescence. The rate of coalescence is an important parameter for predicting the final primary particle size. For some materials, particularly silica, predictions of final primary particle size using coalescence rates based upon bulk material properties are not in agreement with experimental results. One explanation may be that the high internal pressure in very small particles (less than 10 nm in diameter) affects the mobility of material within the particles and hence the coalescence rate. In this Note, a new approach for estimating rates of coalescence of particles in the initial stages of growth is presented. Coalescence of liquid particles is assumed to be rate-limited by atomic mobility, and the effect of internal pressure on diffusivity is considered. Copyright 1999 Academic Press.     

A Simple Liquid Chromatographic Method for the Simultaneous Determination of Antidepressants in Pharmaceutical Preparations

Fluoxetine (FT), fluvoxamine (FX), sertraline (ST) and trazodone (TD) are new type of antidepressants acting as selective serotonin reuptake inhibitors (SSRIs). In structures, they all have chromophore and can be easily monitored by UV absorption spectrophotometry. A simple isocratic high‐performance liquid chromatographic method with ultraviolet detection (215 nm) was developed for the simultaneous quantification of FT, FX, ST and TD. The determination range of the method is over 10.0–400.0 μM for each drug. The detection limits (S/N = 3, injection 20 μL) are about 0.1 μM for TD, 0.2 μM for FT, FX and ST. The relative standard deviation and relative error of the method for intra‐ and inter‐day analyses of FT, FX, ST and TD were all below 3.7%. Application of the method to the analysis of FT, FX or ST in pharmaceutical product proved feasible. The method could be used for the quality control assay of the analytes in bulk and in formulations.     

A Simple Liquid Chromatographic Method for Quantitative Extraction of Hydrophobic Compounds from Aqueous Solutions

Abstract

We are reporting a rapid, high-capacity liquid chromatographic method for quantitative extraction and concentration of hydrophobic compounds from biological fluids and aqueous solutions. Samples are injected into commerically-available cartridges (Sep-Pak C^18R) containing a microparticulate, reversed phase packing which retains hydrophobic compounds. Inorganic salts and organic hydrophilic contaminants are removed with a water wash. Hydrophobic compounds are eluted quantitatively with minimal volumes (～5 ml) of organic solvents. As demonstrated with radiolabeled taurocholate, thin-láyer chromatography, enzymatic fluorimetry and capillary gas chromatography, complete recovery of bile salts from large volumes of urine, serum, amniotic fluid and hydrolysis reaction mixtures was achieved at flow rates up to 20 ml/min. A single cartridge concentrated approximately 50 mg of either taurocholate or the more polar bile salt, taurolithocholate sulfate. The technique is simple and applicable to the isolation of a wide range of hydrophobic compounds from aqueous solutions.     

具有可控分散性的不同粒径氨基酸双功能化介孔二氧化硅纳米颗粒

通过表面活性剂,共结构导向剂（CSDAs）和硅源的自组装合成了具有分散性的不同粒径氨基酸双功能化介孔二氧化硅纳米颗粒. 通过表面活性剂头部与带相反电荷的CSDAs之间的静电相互作用使氨基和羧基基团均匀排列在介孔孔道表面. 通过调节助溶剂或分散剂的加入量来控制颗粒粒径,调节合成溶液pH改变纳米颗粒表面羧基和氨基基团的电荷切换性及其量来控制颗粒的分散性.     

A Simple Liquid Chromatographic Method for Analysis and Isolation of the Unsaturated Components of Anacardic Acid

Abstract

Good analytical and preparative separation of the saturated, monoene, diene and triene components of anacardic acid have been achieved by reverse phase HPLC on a C₁₈ column by isocratic elution with methanol-aqueous acetic acid.     

A Simple Gas Chromatographic Method for the Measurement of Dichloroacetic Acid in Plasma or Urine

Abstract

A method has been developed for measurement of dichloroacetic acid in plasma or urine. The procedure is based on derivatization of dichloroacetic acid with methanol-boron trifluoride, extraction of the resulting methyl ester and gas chromatography. The method has good accuracy and precision, and can be used to determine concentrations as low as 0.04 μg/ml.     

动态光散射法测量颗粒粒径的溯源性

分别对动态光散射粒径测量仪的入射波长、散射角度、测量池温度进行校准,并对影响测量结果准确性各因素的不确定度分量进行了评价,校准后动态光散射仪的测量结果可溯源至国家计量标准。为消除多重散射、颗粒间相互作用、颗粒粒径分布对动态光散射测量结果的影响,建立了动态光散射测量结果修正方法。其中为消除多重散射及颗粒间相互作用的影响,需采用多浓度测量或线性回归的方法得到特定浓度下的颗粒粒径;为修正颗粒粒径分布对动态光散射测量结果的影响,需先采用SEM方法准确测量颗粒粒径分布,然后根据光强加权动力学平均粒径和数量平均粒径的理论公式,得到二者之间的差异。     

A Rapid and Simple High Pressure Liquid Chromatographic Method for Pharmacokinetic Study of Ciprofloxacin in Human Serum

Abstract

A rapid, accurate and sensitive method has been developed for the quantitative determination of ciprofloxacin, a new second-generation quinolone carboxylic acid antimicrobial agent, with high in vitro activity against a wide range of Gram- negative pathogens and Gram-positive cocci.

A Lichrosorb RP-18 250 x 4.0 mm, 5 μm analytical column was used with an eluting system consisting of a mixture of CH₃CN-CH₃OH-Citric acid 0.4 M (1:3:6 v/v). Detection was performed with a variable wavelength UV-visible detector at 275 nm resulting in a limit of detection of 0.2 ng per 20 μl injection. For the quantitative determination theophylline was used as chromatographic internal standard at a concentration of 1.56 ng/μl. A rectilinear relationship was observed up to 20 ng/μl. Analysis time was less than 6 min. The statistical evaluation of the method was examined performing intra-day (n=8) and inter-day calibration (n=8) and was found to be satisfactory with highly accurate and precise results. The method was applied to the direct determination of ciprofloxacin in human blood serum. Sample pretreatment involved only protein precipitation with acetonitrile. Recovery of ciprofloxacin in spiked samples was 98 ± 4% over the range of 0.5–5 mg/μl.     

Thin-Layer Chromatographic Method for Separation of Wheatgrass Pigments on Sucrose Impregnated Silica Gel Plates

JPC – Journal of Planar Chromatography – Modern TLC -     

基于遗传算法的色谱指纹峰配对识别方法

指纹峰配对识别是色谱指纹图谱分析中的关键环节之一，本文提出一种基于遗传算法的色谱指纹峰配对识别方法。该法根据对照色谱指纹图谱的峰分布特性初选出若干标定蜂，将其存入一个候选标定蜂库；同时根据这些候选标定峰从待测指纹图谱中选出相应的候选标定峰，也存入候选标定峰库；再用遗传算法从库中选取一组标定峰用于校正待测指纹图谱中各峰的峰位，并自动识别出与对照色谱指纹图谱相对应的各指纹峰。仿真实验及实际分析实验结果均表明，该法识别指纹峰准确可靠，可用于色谱指纹图谱相似度的快速自动计算。     

Photo-oxidation of Isoprene with Organic Seed: Estimates of Aerosol Size Distributions Evolution and Formation Rates

ondary organic aerosol (SOA) formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investi-gated. It was shown that in the presence of high-level seed aerosol and low-level isoprene (typical urban atmospheric conditions), particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene (typical atmospheric conditions in rural re-gion), bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles indifferent conditions were also estimated.     

Synthesis of Highly ordered Large Size Mesoporous Silica and Effect of Stabilization as Enzyme Supports in Organic Solvent

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Genetic Algorithm Approach to the Determination of Particle Size Distributions from Static Light-Scattering Data

The application of genetic algorithms to the inversion of static light-scattering (SLS) measurements is investigated. The approach is illustrated using simulated data on samples with unimodal, bimodal, and trimodal distributions of spherical particles. Particles having diameters in the range from 100 to 4000 nm are treated. Results are compared with other inversion procedures. It is found that genetic algorithms yield very good results in this situation.     

超大孔聚合物亲和色谱层析介质的制备及评价

探索了用席夫碱法在超大孔聚合物微球表面偶联Protein A配基制备亲和层析介质的方法,以亲水化后的聚丙烯酸酯类超大孔微球为基质,考察了氧化剂浓度(H5IO6)对配基偶联量的影响,以扫描电子显微镜表征微球表面形貌,结果发现其偶联Protein A后微球仍能够保持其大孔结构。考察了该类亲和介质在不同操作流速(361~3 600 cm/h)下的动态载量,在3 600 cm/h操作流速下,人抗体载量与361 cm/h相比仅下降10%左右,表明该类介质适合抗体大分子的快速传质,能够满足快速、高效、高通量分离纯化的需求。     

Use of a Cross-Sectional Model for Determining Rheology in Settling Slurries: Effect of Solvent,Particle Size,and Density

Transport models for partially settling slurries need accurate rheology correlations, particularly describing viscosity relationship to the particle concentration. A method is needed to untangle the effects of settling on apparent viscosity and the real effects of particle concentration on viscosity during rheology measurements. Our approach is based on model inversion of a cross-section model for the vertical particle concentration gradient and the local rheologies in the gap of a Couette type rheometer, established by a balance between gravitational particle settling and shear induced migration of the particles. The Krieger-Dougherty rheology correlation with adjustable parameters has been applied, where the parameters are determined by minimizing the difference between the measured viscosity data and those calculated by the model. Fairly mono-disperse silver coated polystyrene particles with two sizes and densities were used in both the aqueous and oil phase. In the raw data an apparent shear thinning tendency is observed. Through the model inversion process, this is accounted for by the shear dependent settling and the steep increase of viscosity with particle concentration. Maximum packing fraction was obtained through settling experiments. The difference between this value and the maximum packing fraction from the model inversion was less than 3% for oil-based suspensions. The larger difference was found for smaller particle size in water which is attributed to the larger effect of interparticle forces.