大黄素键合硅胶柱高效液相色谱法分离酸性芳香族化合物

本文以传统的C18和苯基柱为参比,将自制的大黄素键合硅胶液相色谱柱(ESP柱)应用于14种芳香族酸性化合物,以及实际样品复方水杨酸搽剂的高效液相色谱(HPLC)分离分析,考察了流动相pH值和甲醇含量对ESP柱分离芳香族酸性化合物的影响,研究ESP柱对酸性化合物的选择性和分离机理。结果表明,在甲醇-0.02mol·L-1KH2PO4(pH=2.5)流动相体系中,三组酸性物质混合样品和实际样品中四种主要成分在ESP柱上实现基线分离。与C18和苯基柱相比,在相同条件下,ESP柱对这类酸性化合物具有较好的选择性,部分芳香酸类化合物的洗脱顺序与C18和苯基柱具有显著差异,其中6种溶质在ESP柱上的保留明显强于C18柱和苯基柱,这说明不同保留机理的存在。研究表明ESP与酸性化合物之间除了存在疏水作用外,p-π和π-π作用、氢键作用、电荷转移作用、偶极-偶极作用对分离也有贡献。与C18和苯基柱相比,丰富的作用机制使ESP柱对极性、电离性物质如对甲苯磺酸、对氨基苯磺酸、苦杏仁酸、间苯二甲酸、对苯二甲酸和水杨酸等具有较强的保留,且分离度有一定的改善。     

Nitric Acid on Silica Gel: A Useful Nitrating Reagent for Activated Aromatic Compounds

Phenols and arylmethyl ethers are rapidly mononitrated by nitric acid adsorbed in silica gel at room temperature in high yields.     

姜黄素键合硅胶固定相高效液相色谱分离取代芳香酸类化合物

研究了13种取代芳香酸类化合物在姜黄素键合硅胶固定相(CCSP)上的色谱行为,考察了甲醇含量、流动相pH值对CCSP分离取代芳香酸类化合物的影响,探讨了该固定相对芳香酸类化合物的色谱保留机理,并应用于实际样品复方水杨酸搽剂的分离分析。结果表明,在不同含量的甲醇-0.02 mol.L-1NaH2PO4(pH=2.5)流动相体系中,三组芳香酸标准混合样和实际样品中四种主要成分在CCSP上实现基线分离。与ODS柱相比,在相同条件下,CCSP对这类酸性化合物具有较高的选择性,且对13种取代芳香酸类化合物的洗脱顺序与ODS具有显著差异,其中5种溶质在CCSP上的保留强于ODS,这说明不同保留机理的存在。研究表明,CCSP具有典型的反相色谱特征,但疏水性较ODS弱;除疏水作用外,n-π和π-π作用、氢键作用、电荷转移作用、偶极-偶极作用对分离也有贡献。CCSP对极性、电离性物质如水杨酸、对硝基苯甲酸、3,4,5-三羟基苯甲酸、邻苯二甲酸和邻溴苯甲酸等具有较强的保留;由于CCSP较弱的疏水性和多种分离机制,邻氯苯甲酸和苯甲酸在CCSP上的保留不会像在ODS上那么强,且分离度明显优于ODS。     

Chromatographic Separation on Silica of Polar Aromatic Compounds

Abstract

Our goal in this work, was to seek the best experimental conditions which allow the migration and partition in thin layer chromatography of numerous aromatic compounds, essentially those of polar character, according to a predominating adsorption process. We then studied the modification of different coefficients intervening in these chromatographies according to accepted experimental conditions. The results with different modes of adsorbent deactivation show that the adsorption process is possible and must be interpreted by the SNYDER Model.     

Ion-Pair Chromatography of Nitrogen-Bridged Compounds on Silica Gel

Abstract

New adsorption operations of high-performance ionpair chromatography have been investigated, using certain types of pharmacologically active nitrogen-bridged compounds. Various chromatographic data are reported. The effect of the counter ion concentration has been studied. Numerous examples of separations are presented.     

Liquid Chromatography of Isomeric Phenols and Aromatic Acids Using a Poly (Ethyleneimine) Coated Silica Gel Micro-Column

Abstract

Ortho-, meta- and para-isomers of various derivatives of phenols and aromatic acids have been separated on a cross-linked poly (ethyleneimine) coated silica gel micro-column liquid chromatography with very dilute carbonate or phosphate eluents.     

A Polymer Coated Silica Gel for High-Performance Liquid Chromatography

Abstract

The treatment of microparticulate silica gel with Carbowax 20M results in a stable and reproducible support which greatly reduces the irreversible adsorption effects observed for polyoxyethylene compounds on untreated silica gel. The selectivity of this coated support, likely a result of selective deactivation, permits the rapid separation of oligomers differing by ≤ 3% in molecular weight. The advantages and disadvantages of this support and a C₁₈ reversed-phase support for the separation and analysis of polyoxyethylene oligomers and their adducts are illustrated and discussed.     

Spherical Versus Irregular-Shaped Silica Gel Particles in HPLC

Abstract

With optimised packing procedures, spherical shaped silica gel particles produce 1.5 to 2 times more plates in HPLC than irregular shaped silica gel particles. The lowest reduced plate height obtained by us so far is for 5 μm ROSiL-C₁₈-HL-D and is h: 1.62 for k': 4.5. It is suggested to transform h into 100/h% and to name this the “Chromatographic efficiency”, or a % of the ideal 100% limit. This limit would be an h value equal to the mean particle diameter. Spherical and irregular silica gel particles of 5 and 10 μm particle diameter and with similar physical characteristics have the same permeability in HPLC columns.

Whether a correct column packing procedure is used can be shown by the constancy of plate number and column permeability in function of different packing pressures.     

无孔单分散离子交换硅胶键合相用于蛋白质的高效液相色谱分离

将新合成的无孔硅胶二乙基氨基新型离子交换填料 (NPS-DEA)用于蛋白质的液相色谱分离。考察了流动相的pH值、盐浓度、流速及梯度程序对蛋白质分离的影响 ,并考察了蛋白质的质量回收率。实验结果表明 ,所得阴离子交换固定相的色谱性能良好。在梯度淋洗条件下 ,卵清蛋白、牛血清蛋白、胰岛素、γ-球蛋白、核糖核酸酶、溶菌酶获得了较好的分离。蛋白质的保留符合一般的保留值规律。柱填充床稳定 ,而柱负载较小 ,可用于高纯度的微量制备。     

硅胶自环己烷中吸附含氧芳香化合物的研究

测定了15℃和30℃时硅胶自环己烷中吸附苯甲醇、苯甲醚、苯甲醛和苯甲酸的吸附等温线,这些等温线皆可用Langmuir公式表示。利用Langmuir常数n_m^s和b值计算了吸附过程的△G⁰、△H⁰和△S⁰;四种化合物的△S⁰皆为正值。测定了在较大复盖度时红外光谱图上硅胶表面自由羟基峰的移动值△v_OH。结果表明△H⁰和△v_OH及△v_OH^1/2间有线性关系。文中对所得结果做了初步的解释。     

Caro's Acid Supported on Silica Gel. Part V: A Mild and Selective Reagent for Conversion of Trimethyl Silyl ethers to the Corresponding Hydroxy Compounds

Mild and efficient method for deprotection of silyl ethers to alcohols is described using Caro's acid supported on silica gel. Reactions are carried out in dichloromethane at room temperature and their parent hydroxy compounds obtained in good to excellent yields. Using this procedure, tetrahydropyranyl ethers (THP) remain intact during desilylation reaction.

     

姜黄素键合硅胶固定相HPLC分离碱性化合物

反相高效液相色谱法;姜黄素键合硅胶固定相;碱性化合物;色谱保留机理     

Analysis of Quaternary Ammonium Compounds by Ion-Pair Thin Layer Chromatography on Silica Gel

Abstract

A general approach to the chromatographic analysis of quaternary ammonium compounds on silica gel thin layers is described. The quaternary cations migrate as ion pairs with bromide or iodide as counter ions. Methanol or chloroform-methanol mixtures serve as developing solvents, in which excess amounts of NaBr or NaI are dissolved. If the solvent cannot dissolve sufficient quantities of halide salts, the latter can be sprayed onto the plate as a methanol solution prior to development. The separation patterns of the quaternary ammonium compounds can be influenced by the choice of counter ion and by the choice of the organic solvent components.     

高速逆流色谱与硅胶柱色谱结合分离制备高纯度芦荟素异构体

芦荟素是芦荟叶中主要的蒽醌类成分,通常以芦荟素A和B两种非对映异构体形式并存,目前已成为许多芦荟产品质量控制指标之一。采用高速逆流色谱和硅胶柱色谱结合的方法,从老芦荟干粉中分离制备了高纯度的芦荟素A(纯度为98%)和芦荟素B(纯度为96%)样品,并采用快原子轰击质谱(FAB-MS)和核磁共振氢谱(1H NMR)以及GOESY(gradient-enhanced nuclear Overhauser effect spectroscopy)等方法对所得的两个芦荟素异构体的立体构象进行了确认。该法具有制备量大和分离效率高的特点。     

Preparative Electrochromatography of Tea Polyphenols and Caffeine

A novel low-pressure preparative electrochromatography apparatus was set up to implement the separation of small polar compounds. In this apparatus, a distinguished bottom “T”-shape electrode chamber was designed to remove electrolysis gas and meanwhile enable the apparatus to separate small-molecule solutes. Partial separation of the model sample, crude tea extract (mainly containing (−)-epigallocatechin gallate, (−)-epicatechin gallate and caffeine) by hydrophobic macroporous adsorption column (maximum 40 cm × 20 mm ID) with electric field (maximum 111.0 V cm⁻¹) proved the effectiveness of the electrochromatography apparatus. The fact that the total solute recoveries were over 90% showed the qualification of the apparatus for preparative purpose. The stronger the electric field, the more obvious the electrically induced effects. An alternative in-liquid load manner (loading sample in liquid after the electric field was applied) was proposed, which could further enhance the electrically induced effects than in-column load manner (loading sample on resin bed before applying electric field). Scale-up on electrochromatography by column diameter from 6 to 20 mm resulted in similar electrically induced effects on peak resolutions. All of these investigations revealed that the new technology was feasible and promising on separating small polar compounds, for it inherits the advantages of both liquid chromatography and electrophoresis.

     

Preparative Electrochromatography of Tea Polyphenols and Caffeine

A novel low-pressure preparative electrochromatography apparatus was set up to implement the separation of small polar compounds. In this apparatus, a distinguished bottom “T”-shape electrode chamber was designed to remove electrolysis gas and meanwhile enable the apparatus to separate small-molecule solutes. Partial separation of the model sample, crude tea extract (mainly containing (?)-epigallocatechin gallate, (?)-epicatechin gallate and caffeine) by hydrophobic macroporous adsorption column (maximum 40 cm × 20 mm ID) with electric field (maximum 111.0 V cm^?1) proved the effectiveness of the electrochromatography apparatus. The fact that the total solute recoveries were over 90% showed the qualification of the apparatus for preparative purpose. The stronger the electric field, the more obvious the electrically induced effects. An alternative in-liquid load manner (loading sample in liquid after the electric field was applied) was proposed, which could further enhance the electrically induced effects than in-column load manner (loading sample on resin bed before applying electric field). Scale-up on electrochromatography by column diameter from 6 to 20 mm resulted in similar electrically induced effects on peak resolutions. All of these investigations revealed that the new technology was feasible and promising on separating small polar compounds, for it inherits the advantages of both liquid chromatography and electrophoresis.     

HPLC法同时测定尿样中芳香族化合物的6种代谢产物

建立了同时测定尿样中反,反-粘康酸、马尿酸、苯乙醇酸、苯乙醛酸、对氨基酚和对硝基酚的高效液相色谱法(HPLC).优化了色谱分离及检测条件,并采用时间程序波长检测.确定了最佳样品预处理条件:以5 mL二氯甲烷-异丙醇(7∶3)为萃取溶剂;样品用量5 mL;NaCI加入量0.75 g;萃取时间2 min,分别在酸性和中性条...     

Preparative HPLC of carotenoids

Summary A method is described for the preparative HPLC of up to 50mg of carotenoid using a self-packing axially-compressed column. Oxygenated carotenoids, xanthophylls, are separated with silica as the stationary phase and acetone/petroleum ether as the mobile phase, while carotenes are separated using magnesium oxide/polyamide as the stationary phase and undiluted petroleum ether as the mobile phase.     

Preparation and Evaluation of 3,5-Dinitrobenzoyl-Bonded Silica Gel Stationary Phase for HPLC

Column packing materials are always a key factor influencing the development of high-performance liquid chromatography (HPLC). In this paper, a new preparation method of 3,5-dinitrobenzoyl-bonded silica gel stationary phase (DNB) for HPLC was developed by using N-(β-aminoethyl)-γ-aminopropyl-methyldimethoxy silane as coupling reagent. Its structure was characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy, and thermal analysis. The surface concentration of 3,5-dinitrobenzoyl ligand is 2.082 μmol m⁻², according to the carbon content of elemental analysis. The chromatographic performance of new packing was evaluated by using different solute probes, such as alkylbenzenes, polycyclic hydrocarbons (PAHs), phenols, naphthalene derivatives, nitrophenol positional isomers, and sulfonamides. The results show that DNB was of the reversed-phase packing kind with weak hydrophobicity and versatile chromatographic property compared with octadecyl silane. The charge transfer between the dinitrobenzoyl ligand and the analytes plays a significant role in the separation of phenols and naphthalene derivatives. In addition, electrostatic, hydrogen-bonding, and dipole-dipole interactions are responsible for the above separations, which improve the selectivity of DNB for solutes. An advantage of DNB is that it is suitable for the separation of the basic compounds containing nitrogen atoms without a capped process because the spacer containing nitrogen atoms can shield the residual silanols from DNB. Translated from Chinese Journal of Chromatography, 2005, 23(3) (in Chinese)