Preparative medium pressure liquid chromatographic (MPLC) and semipreparative HPLC separation of furocoumarin isomers

Chromatographia - Preparative medium pressure liquid chromatography and semi-preparative high performance liquid chromatography on silica were employed for the isolation of eight furocoumarin...     

New stationary phases for normal-phase HPLC based on silica gel modified with cobalt,nickel, zinc,and cadmium salts

Several new stationary phases for normal-phase high-performance liquid chromatography were synthesized by the modification of silica gel with cobalt, nickel, zinc, and cadmium salts and subsequent calcination at 700°C. These sorbents exhibit an increase in the retention of organic compounds of the basic character, an increase in the selectivity of separation, and an eightfold increase in efficiency in comparison with initial silica gel. The experimental results were explained on the basis of the interpretation of the IR spectra of pyridine adsorbed on the synthesized and initial silica gel. It was demonstrated that the surface of silica gel modified with cadmium ions exhibits the highest acidity. The advantage of the synthesized sorbents was demonstrated with the example of the separation of fullerenes containing diethylamino and hydroxy groups.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 412–416.Original Russian Text Copyright © 2005 by Pirogov, Kuzavlev, Shpigun.     

Preparative isolation and purification of celastrol from Celastrus orbiculatus Thunb. by a new counter-current chromatography method with an upright coil planet centrifuge

A new counter-current chromatography (CCC) method with an upright coil planet centrifuge, which holds four identical multilayer coil columns in the symmetrical positions around the centrifuge axis, was applied to the isolation and purification of celastrol from the roots of Celastrus orbiculatus Thunb. The crude celastrol was obtained by elution with light petroleum from ethanol extracts using 15 cm x 5 cm i.d. silica gel flash chromatography. Preparative CCC with a two-phase system composed of light petroleum (bp 60-90 degrees C)-ethyl acetate-tetrachloromethane-methanol-water (1:1:8:6:1, v/v) was successfully performed, yielding 798 mg celastrol at 99.5% purity from 1020 mg of the crude sample in one step separation.     

Recent progress in carbohydrate separation by high-performance liquid chromatography based on hydrophilic interaction

This article surveys recent developments in the separation and analysis of carbohydrates by high-performance liquid chromatography, in adsorption or partition modes, on polar sorbents with less polar eluents, a technique that is now termed hydrophilic interaction chromatography. A variety of chromatographic methods are included under this generic heading, the most important being adsorption chromatography on silica and partition chromatography on silica-based sorbents bearing bonded polar phases. Examples are given of the applications of these stationary phases, as well as the newer polymer-based polar sorbents, in high-performance liquid chromatography of carbohydrates and their derivatives.     

Utilization of Weak Acid-Base Interactions to Improve Separations in Normal Phase Liquid Preparative Chromatography

Abstract

Three 40 μm derivatized silicas, two aminoalkyl and one carboxyalkyl, have been compared to 40 μm silica gel for performance in normal phase preparative liquid chromatography. The three derivatives showed higher selectivity for compounds capable of hydrogen-bond formation or acid-base interactions. Retention times were related to the basicity of the amine bonded derivatives or the acidity of the carboxylic acid derivative and the pK values of the solutes. The advantages for each of the four sorbents for neutral, acidic and basic compounds have been described.     

Protein Purification on a New Preparative Ion Exchanger

Abstract

The ACCELL chromatographic media is a new packing designed specifically for the isolation and purification of proteins. The anionic and cationic functional groups are bonded to an encapsulated 40μ silica particle which can be readily packed into any size column. These columns can be operated on both high performance and medium performance liquid chromatographic equipment. The optimization of the separation conditions on the anion exchange media for the preparative purification of a monoclonal antibody (Mab) from ascites will be discussed as well as a multi-step purification of the enzyme prostatic acid phosphatase (PAP) from seminal fluids on the anion and cation exchangers.     

A Quarter Century of Thin-Layer Chromatography—An Interim Report

Thin-layer chromatography (TLC) has been in general use since 1958. The prerequisites were the use of very small particle size material in the layers and the demonstration that not only lipophilic mixtures but also mixtures of cardiac glycosides, alkaloids, sugars, and amino acids could be separated quickly and simply on silica gel layers. The impressive separations obtained using the method later encouraged attempts to use adsorbants having such, narrow-range small particles in column chromatography. In order to achieve sufficient flow rates the use of high pressures was necessary. Thus, high pressure or high performance liquid chromatography (HPLC) was born, whose godfather, as far as instrumental development is concerned, was gas chromatography (GC). Today, chromatography is classified according to the nature of the transport phase: liquid, gas, or “electro” chromatography. Sample preparation often requires more time than the actual separation. rapid thermal separation and application techniques (TAS, TFG) have brought advantages to TLC. As before, the art of chromatography consists in choosing the appropriate mobile phase, stationary phase, and separation technique. Gradient TLC offers new possibilities; for example, gradient layers make it possible to obtain selective information on the individual components of a mixture and also allow significant focussing effects to be achieved. Sequential and centrifugal TLC have paved the way for further advances. The questions arise whether the standard conditions, formulated 25 years ago, are still applicable and how the variations which have been introduced should be judged. Group- and substance specific methods of detection are discussed in addition to universal methods. Quantitation is critically discussed and it is concluded that HPLC has the better chance in the furture. Combination and coupling techniques ease the positive identification of individual substances. Finally, it is discussed why TLC is the simplest, most versatile, most cost effective, and most widely used chromatographic method and reasons are proposed as to why it will remain so for the foreseeable future.     

应用新型立式逆流色谱制备分离南蛇藤中的南蛇藤素

A versatile countercurrent chromatography with upright multilayer coil planet centrifuge, named upright countercurrent chromatography (UCCC), was applied to the isolation and purification of celastrol from the roots of Celastrus orbiculatus Thunb. The crude celastrol was obtained by elution with petroleum ether from ethanol extracts using a 15 cm length and 5 cm I.D. of silica gel flash chromatography. Preparative UCCC (Fig. 1) with a two-phase system composed of petroleum ether (b. p. 60 ～ 90 ℃ )-ethyl acetate-tetrachloromethanemethanol-water ( 1:1:8:6: 1, v/v) was successfully performed, yielding 705 mg celastrol at 99.5 % purity from 1020 rng of the crude extract in one step separation.     

Preparative isolation and purification of syringin and edgeworoside C from Edgeworthia chrysantha Lindl by high-speed counter-current chromatography

The bioactive compound syringin along with edgeworoside C were separated from the n-butanol extract of the stems and barks of Edgeworthia chrysantha Lindl (E. papyrifera) by high-speed counter-current chromatography (HSCCC) while it was difficult to purify each compound by silica gel column chromatography. Syringin was isolated from this plant for the first time. The two-phase solvent system used was composed of ethyl acetate-ethanol-water at an optimized volume ratio of 15:1:15 (v/v/v). Preparative HSCCC yielded, from 110mg of the partially purified extract, 28mg of syringin and 45 mg edgeworoside C each at over 96% purity by high-performance liquid chromatography analysis. Their structures were identified by electron impact ionization MS, 1H NMR and 13C NMR.     

高效制备液相色谱柱技术的研究进展

本文概述了高效制备液相色谱柱的柱型结构、填料以及柱填充方法等研究的最新进展,讨论了制备柱与分析柱的不同特征,对目前普遍使用的压缩型制备柱的类型、结构及填充方法作了较为全面的评述,总结比较了工业化制备色谱填料不同于分析色谱填料的特点,探讨了高效制备液相色谱柱技术的应用和发展前景.     

Preparative Purification and Isolation of Pyranoanthocyanins from Red Wine and Evaluation of Their Antioxidant Activity

Untreated silica gel was used as the stationary phase for a simple and cost-effective prepurification of 5-carboxypyranoanthocyanins from red wine enriched by the addition of pyruvic acid. The composition of the fractions obtained was analyzed by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC/MS²) and the results enabled the changes in 5-carboxypyranoanthocyanin profile during preparative separation to be described and explained. Repeated purification on silica gel followed by reversed-phase separation enabled the isolation of 5-carboxypyranomalvidin-3-glucoside in high purity and represents a cheap and robust alternative to the commonly used procedures. Reversed-phase preparative chromatography with an isocratic elution [15 % acetonitrile in water (v/v)] provided sufficient resolution, showing that the addition of an acid is not necessary in anthocyanin separation. The antioxidant capacity of 5-carboxypyranomalvidin-3-glucoside was compared with malvidin-3-glucoside and a group of common polyphenols (e.g., gallic acid, quercetin, rutin, and catechin).     

Preparative argentation reversed-phase high performance liquid chromatography

In this study, a preparative chromatography method named preparative argentation reversed-phase high performance liquid chromatography (Ag-RP-HPLC) was developed by adding silver ion to the mobile phase of preparative HPLC. Firstly, an analytical Ag-RP-HPLC method was developed, and the effects of silver content and acid content in the mobile phase on the column efficiency were studied. Based on the method of linear amplification, a preparative Ag-RP-HPLC technique with optimized separation conditions was developed. The new technique was applied successfully to the separation of the unsaturated aliphatic acid amide isomers contained in Asarum forbesii Maxim. Compared with the commonly used technique of argentation normal phase chromatography, this method with little solvent consumption is simple, fast, efficient, and flexible for the isolation and purification of the unsaturated compounds.     

Preparative separation of five flavones from flowers of Polygonum cuspidatum by high‐speed countercurrent chromatography

A preparative high‐speed countercurrent chromatography method was successfully used for the isolation of five minor flavones from Polygonum cuspidatum flowers. Among them, three compounds were obtained from P. cuspidatum for the first time. A twin two‐phase solvent system composed of n‐hexane/ethyl acetate/ethanol/water (1:6:3:6, v/v/v/v) and petroleum ether/ethyl acetate/methanol/water (2:4:3:3, v/v/v/v) was developed. Compounds were obtained from the fraction B and fraction C prepurified by silica gel column chromatography. Five minor compositions, 6.8 mg of hesperidin, 11.2 mg of phloridzin, 4.9 mg of luteolin, 5.3 mg of hyperin, and 3.7 mg of luteoloside were obtained from 140 mg of the fraction B and 110 mg of fraction C with a purity of 95.3, 96.4, 98.0, 96.8, and 95.3%, respectively, as determined by high‐performance liquid chromatography. The structures of these compounds were identified by ¹H and ¹³C NMR spectroscopy.     

应用立式逆流色谱和反相液相色谱制备性分离荜菝中的酰胺类化合物

A versatile countercurrent chromatography with upright type-J multilayer coil planet centrifuge,named upright countercurrent chromatography (UCCC),was applied to the isolation and purification of amides from Piper Longum L., which is widely used as an anodyne and a treatment for stomach disease in China. After saponification by KOH of the ethanol extracts solution of crud drug "Piper Longi Fructus", the fruits of Piper Longum L., the remaining solution was extracted with petroleum ether and red crude oil was obtained. Using 2.5 g red crude oil as sample, the preparative UCCC with a two-phase system composed of petroleum ether (b. p. 60 ～ 90 ℃)-ethyl acetate-tetrachloromethanemethanol-water ( 1: 1: 8: 6: 1, v/v) was successfully performed, yielding ten fractions. Then these fractions were further purified by use of reversed-phase liquid chromatography with a glass column of 500 × 10 mm I. D.packed with reversed - phase silica gel. As a result,nine amides with more than 98% purity, i.e., (2E,4E)-N-isobutyl-eicosa-2,4-dienamide, (2E, 4E, 8Z)-N-isobutyl-eicosa-2,4,8-trienamide, (2E, 4E, 8Z)-N-isobutyl-ocatadeca-2,4,8-trienamide, guineensine, pipemonaline, ( 2E, 4E )-N-isobutyl-2, 4-didecadienamide, piperine, piperanine, and piperlonguminine were isolated preparatively.     

Modelling of n-alkane retention and optimization of the conditions for analysis in gas adsorption chromatography with temperature programming

Summary The possibility of constructing a mathematical model of n-alkanes retention upon their separation by gas solid chromatography with temperature programming has been studied. The functional dependence between the number of the carbon atoms in n-alkane molecules, their retention in isothermal conditions and temperature of chromatographic column was used for constructing this mathematical model. It showed necessary to take into account the variance in the process temperature programming of both the carrier gas volume velocity and the column inlet pressure to obtain the adequate mathematical model of the chromatographic retention. With the use of the specific retention parameters of substances i.e. relative to the surface or the mass of sorbents the proposed model can be used not only for Silochrom C-80 but for the whole class of macroporous silica sorbents.     

高速逆流色谱法从蝙蝠蛾拟青霉中快速分离制备麦角甾醇纯品

建立了用高速逆流色谱从蝙蝠蛾拟青霉中高效、快速分离制备高纯度麦角甾醇的方法。将蝙蝠蛾拟青霉的乙酸乙酯提取物直接进行高速逆流色谱分离,考察了不同溶剂系统的分离效果。结果表明,最佳的溶剂系统为正己烷-乙酸乙酯-甲醇-水(体积比为6:1.7:6:0.3),以上相为固定相,下相为流动相,转速为850 r/min,流速为2 mL/min,检测波长为280 nm。制备所得的麦角甾醇经紫外光谱(UV)和高分辨质谱(HRMS)鉴定及与标准品对照定性;纯度经高效液相色谱(HPLC)分析为99.2%(峰面积归一化法)。该方法制备麦角甾醇简便、快速,所得产物的纯度高,适合于麦角甾醇对照品的制备。     

烷基酚聚氧乙烯醚在不同液相色谱分离模式中的分离研究

考察了烷基酚聚氧乙烯醚在反相色谱、正相键合色谱、硅胶吸附色谱、体积排阻色谱4种不同液相色谱分离模式中的分离效果,分别采用Kromasil C_(18)(250 mm× 4.6 mm,5 μm)、Agilent ZORBAX NH2(250 mm× 4.6 mm,5 μm)、Waters Spherisorb S3W(150 mm×2.0 mm,3 μm)和Shodex MSpak GF-310 2D(150 mm×2.0 mm,5 μm)色谱柱,以225 nm为紫外检测波长,对不同液相色谱分离模式的流动相组成、梯度洗脱条件、柱温、流速等进行了优化,并对烷基酚聚氧乙烯醚在不同液相色谱分离模式中的保留机理进行了初步探讨.结果表明,正相键合色谱实现了烷基酚聚氧乙烯醚的最佳分离;硅胶吸附色谱和体积排阻色谱的分离效果较正相键合色谱稍差.     

Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high‐performance liquid chromatography

In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high‐performance liquid chromatography. The new stationary phase could be used in both reversed‐phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π‐electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero‐dimensional GNPs.