快速色谱

基于柱液相色谱和薄层色谱之间的关系,讨论如何为快速色谱选择流动相,并介绍此技术手工操作的步骤.     

Extraction chromatography of common anions in liquid-liquid anion exchange systems. Part. III. Monobasic aliphatic organic acids and their sodium salts as eluants

Summary The chromatographic behaviour of anions on paper strips treated with tri-n-octylamine (TOA) salts or Aliquat 336 and developed with aqueous solutions of acetic, formic, monochloroacetic or trifluoroacetic acids and their sodium salts was investigated. Liquid-liquid extraction of organic acids by 0.1 M solution of TOA in benzene as well as the anion exchange between benzene solutions of TOA salts or Aliquat 336 (in acetate form) in benzene and aqueous solutions of sodium halides was also studied. It was found that extraction increases in the following order of the acids: CH₃COOOH<HCOOH<CH₂CICOOH<CF₃COOH; the relative affinity of organic anions to the quaternary alkyl-ammonium cation also increase in a similar order. The extraction of acid in excess over the amount necessary to neutralize the amine was observed for all four acids. The R_F values of anions investigated depend markedly on the type of organic acids or their salts and their concentration in the mobile phase. Halide ions are more strongly retained on paper treated with Aliquat 336 as compared with TOA salts. The chromatographic systems investigated offer many possibilities to separate various anion mixtures.Parts and II: refs. [1, 2].     

Unified chromatography: Fundamentals,instrumentation and applications†

The concept of unified chromatography has been in existence for 50 years after the work of Giddings proposing that all modes of chromatography (gas chromatography, liquid chromatography, supercritical fluid chromatography and so on) may be treated together under a single unified theory. His idea was partially fulfilled 23 years later by Ishii, Takeuchi and colleagues, who demonstrated for the first time the possibility to analyze a complex sample containing substances with a wide range of boiling points and polarities in the same instrument and column, just by varying the mobile phase pressure and temperature to change from one chromatographic mode to another. This approach has been demonstrated through application to the separation of complex mixtures in several areas including crude oil, edible oils and polymers. Still, unified chromatography has not yet been fully developed. In the present work, we will review the fundamentals, instrumentation and several applications of the technique. Also discussed are the drawbacks that still hinder development, as well as the recent developments and trends in instrumentation and columns that suggest the most feasible ways forward to the full development of unified chromatography.     

A review of advances in two-dimensional thin-layer chromatography

Although there are many simple thin-layer chromatography (TLC) separations, many more are complex and involve more than a few components, that means having to use special high-performance TLC (HPTLC) plates or microspotting or banding devices to increase its resolving power if developing in only one direction. However, adding a second development to perform two-dimensional TLC (2D TLC) allows even better resolution of complex samples. This is because different modes of chromatography are being invoked by the use of one stationary phase with two mobile phases, bilayer plates, graft TLC, or multidimensional TLC. This paper is a review of recent applications that have benefitted from using 2D TLC in its various forms. They were chosen for their variety of sample types as well as the unique choices of plates and/or mobile phases made by the researchers to yield improved separations.     

TLC as a pilot technique for the optimization of gradient HPLC II. Use of data obtained from RP-18 plates for the prediction of gradient programs in reversed-phase liquid chromatography

Summary A method is described and experimentally verified permitting the determination of the optimal gradient programs in HPLC on the basis of isocratic TLC data. The proposed method has many advantages and can also be used in reversed-phase systems. A satisfactory agreement between the theoretical and experimental of V_R/V_O values has been confirmed. Some discrepancies for more strongly retained solutes are, probably due to the respective equilibrium and nonequilibrium state of the column in isocratic and gradient elution.Part I: Ref. [1].     

Exhibition of the first gas chromatographic work of Erika Cremer and Fritz Prior

Summary In November 1995, theDeutsches Museum, the world's largest technical museum, opened a new branch in Bonn, devoted to achievements after 1945. There, the first gas chromatographic system used by Erika Cremer and Fritz Prior, in 1945–47, in Innsbruck, is exhibited. The new display is described and the early activities of Erika Cremer and her students are summarized.     

茶多酚的色谱分析法

 对茶多酚的主要成分――儿茶素的色谱分析法进行了综述。重点介绍了应用最多的反相高 效液相色谱法,同时简述了平板色谱法、气相色谱法以及目前出现的新的色谱分析方法。     

Affinity monolith chromatography: A review of general principles and recent developments

Affinity monolith chromatography (AMC) is a liquid chromatographic technique that utilizes a monolithic support with a biological ligand or related binding agent to isolate, enrich, or detect a target analyte in a complex matrix. The target-specific interaction exhibited by the binding agents makes AMC attractive for the separation or detection of a wide range of compounds. This article will review the basic principles of AMC and recent developments in this field. The supports used in AMC will be discussed, including organic, inorganic, hybrid, carbohydrate, and cryogel monoliths. Schemes for attaching binding agents to these monoliths will be examined as well, such as covalent immobilization, biospecific adsorption, entrapment, molecular imprinting, and coordination methods. An overview will then be given of binding agents that have recently been used in AMC, along with their applications. These applications will include bioaffinity chromatography, immunoaffinity chromatography, immobilized metal-ion affinity chromatography, and dye-ligand or biomimetic affinity chromatography. The use of AMC in chiral separations and biointeraction studies will also be discussed.     

Investigation of some modes of flat-bed chromatography

A comparison of different chromatographic methods is presented: column liquid chromatography (CLC), thin layer chromatography (TLC), and continuous-elution flat-bed chromatography (CEFBC), which is in fact a combination of the first two methods. In CEFBC a sample is applied to a sorbent layer in a steady flow of eluent, and the components are detected directly on the layer, or immediately upon leaving it, during the separation process. It is shown that evaluation of the separation processes in CEFBC is best accomplished in terms of the parameters applicable in CLC. The reproducibility of the analytical results obtained by CEFBC is better than in the case of TLC by a factor of 6 to 10, and approaches that known for CLC.     

Two-dimensional ion chromatography using tandem ion-exchange columns with gradient-pulse column switching

A two-dimensional ion chromatography (2D-IC) approach has been developed which provides greater resolution of complex samples than is possible currently using a single column. Two columns containing different stationary phases are connected via a tee-piece, which enables an additional eluent flow and independent control of eluent concentration on each column. The resultant mixed eluent flow at the tee-piece can be varied to produce a different eluent concentration on the second column. This allows analytes strongly retained on the first column to be separated rapidly on the second column, whilst maintaining a highly efficient, well resolved separation of analytes retained weakly on the first column. A group of 18 inorganic anions has been separated to demonstrate the utility of this approach and the proposed 2D-IC method provided separation of this mixture with resolution of all analytes greater than 1.3. Careful optimisation of the eluent profiles on both columns resulted in run times of less than 28 min, including re-equilibration. Separations were performed using isocratic or gradient elution on the first column, with an isocratic separation being used on the second column. Switching of the analytes onto the second column was performed using a gradient pulse of concentrated eluent to quickly elute strongly retained analytes from the first column onto the second column. The separations were highly repeatable (RSD of 0.01–0.12% for retention times and 0.08–2.9% for peak areas) and efficient (typically 8000–260,000 plates). Detection limits were 3–80 ppb.     

蛋白质制备色谱的研究

研究了蛋白质纯化制备的二种运行模式,其一,在色谱柱超载下纯化制备蛋白质模式,并成功地用离子交换色谱纯化制备了大豆中的胰蛋白酶,用反相液相色谱纯化了细胞色素Ｃ;其二,用溶质－溶质顶替色谱纯化制备了核糖核酸酶－Ａ,并对顶替色谱过程中诸参数进行了讨论和选择。     

A reversed-phase/hydrophilic interaction mixed-mode C18-Diol stationary phase for multiple applications

A mixed-mode chromatographic packing material, C18 and diol groups modified silica (C18-Diol), was prepared with controllable hydrophobicity and hydrophilicity. It demonstrated excellent aqueous compatibility and stability in aqueous mobile phase; compared to the traditional C18 column, improved peak shape of basic analytes was also obtained. Additionally, it exhibited both reversed-phase liquid chromatographic (RPLC) and hydrophilic interaction chromatographic (HILIC) performance; the analyte separation scope was thus enlarged, demonstrated by simultaneous separation of twenty acids, bases and neutrals. More interestingly, a novel on-line two-dimensional liquid chromatography on the single column (2D-LC-1C) was established by modifying the high performance liquid chromatographic instrument only with the addition of an extra six-port two-position valve. The early co-eluted components of the extract of Lonicera japonica on the 1st-dimension (RPLC) were collected for the online re-injection to the 2nd-dimension (HILIC) by conveniently varying the mobile phase components. Six more peaks were obtained. The established system was simple, easy operation and low cost, which had advantages in analyzing complicated samples.     

高效膜色谱的发展和应用

对新兴的高效膜色谱的基质材料、膜形态、分离机理以及应用进行了综述,并对其用于对映体分离作了展望。共７６篇。     

Studies on separation mechanisms of biological molecules on a polyvinyl alcohol column

Summary The chromatographic separation mechanism on a polyvinyl alcohol (PVA) column in aqueous systems was explored utilizing several different types of compound such as polyethylene glycols, carbohydrates, pyrimidine and purine bases, fatty acids, monophosphate nucleotides and glycyl-peptides. Two types of separation mechanisms were found to occur for these substrates. The polyethylene glycols and the carbohydrates were eluted by size-exclusion chromatography. The retention behavior of the other substrates could be explained by the solvophobic theory, suggesting that the predominant separation mode was reversed-phase chromatography. The occurrence of reversed-phase chromatography was also indicated by the remarkable effect of the addition of ion-association reagents to the chromatographic system on the retention of the monophosphate nucleotides.     

Preparation,evaluation, and application of a novel reversed-phase/zwitterionic/hydrophilic interaction liquid chromatographic mixed-mode stationary phase

The present study described the preparation and application of a reversed-phase/zwitterionic/hydrophilic interaction liquid chromatography stationary phase, named as SIL-PS. The SIL-PS was prepared through a four-step reaction, chemical bonding, nucleophilic addition, SN1 substitution, and sulfonation on the silica matrix. It was featured with C₁₂ alkyl chain, quaternary ammonium, tertiary amine, and sulfonate groups. After SIL-PS was packed into the stainless steel column (150?× 2.1 mm i.d.), chromatographic parameters, including acetonitrile content, pH, and ionic strength of the mobile phase, and the column temperature, were systematically investigated to study the retention mechanism. Electrostatic adsorptive/repulsive, partition, and hydrogen-bonding interactions were demonstrated to contribute to the retention. The stability of the SIL-PS was satisfactory, with relative standard deviations of retention factors of 1.93, 2.08, and 1.90% for loxoprofen, adenosine, and liquiritin, respectively. Additionally, to investigate the separation selectivity, the non-steroidal anti-inflammatory drugs, nucleobases/nucleotides, and alkaloids/glycosides were separated; the HPLC fingerprinting of the Cortex phellodendri extract was also conducted, and the separation performance was superior to that of the C18 column in terms of peak shape, resolution, and analytical time. The results revealed that the prepared SIL-PS possessed multifunctionalities for multiretention and could be promising for complicated samples.     

Fast and efficient size-based separations of polymers using ultra-high-pressure liquid chromatography

Ultra-high-pressure liquid chromatography (UHPLC) has great potential for the separations of both small molecules and polymers. However, the implementation of UHPLC for the analysis of macromolecules invokes several problems. First, to provide information on the molecular-weight distribution of a polymer, size-exclusion (SEC) columns with specific pore sizes are needed. Development of packing materials with large pore diameters and pore volumes which are mechanically stable at ultra-high-pressures is a technological challenge. Additionally, narrow-bore columns are typically used in UHPLC to minimize the problem of heat dissipation. Such columns pose stringent requirements on the extra-column dispersion, especially for large (slowly diffusing) molecules. Finally, UHPLC conditions generate high shear rates, which may affect polymer chains. The possibilities and limitations of UHPLC for size-based separations of polymers are addressed in the present study. We demonstrate the feasibility of conducting efficient and very fast size-based separations of polymers using conventional and wide-bore (4.6 mm I.D.) UHPLC columns. The wider columns allow minimization of the extra-column contribution to the observed peak widths down to an insignificant level. Reliable SEC separations of polymers with molecular weights up to ca. 50 kDa are achieved within less than 1 min at pressures of about 66 MPa. Due to the small particles used in UHPLC it is possible to separate high-molecular-weight polymers (50 kDa ≤ M(r) ≤ 1-3 MDa, upper limit depends on the flow rate) in the hydrodynamic-chromatography (HDC) mode. Very fast and efficient HDC separations are presented. For very large polymer molecules (typically larger than several MDa, depending on the flow rate) two chromatographic peaks are observed. This is attributed to the onset of molecular deformation at high shear rates and the simultaneous actions of hydrodynamic and slalom chromatography.     

Large-scale isolation and purification of geniposide from the fruit of Gardenia jasminoides Ellis by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) was applied to the isolation and purification of geniposide from Gardenia jasminoides Ellis. Analytical HSCCC was used for the preliminary selection of a suitable solvent system composed of ethyl acetate-n-butanol-water (2:1:3, v/v/v). According to the above solvent system, preparative HSCCC was successfully performed with the optimal solvent system composed of ethyl acetate-n-butanol-water (2:1.5:3, v/v/v) yielding 389 mg of geniposide at over 98% purity from 1g of the partially purified extract with 38.9% recovery in a one-step separation.