Purification of alkaloids from Corydalis yanhusuo W. T. Wang using preparative 2‐D HPLC

Two‐dimensional preparative multi‐channel parallel high performance liquid chromatography was successfully applied for the first time to isolate and purify alkaloids from Corydalis yanhusuo. The experiments were performed in off‐line mode using the same preparative chromatographic column with pH 3.5 in the first and pH 10.0 in the second separation dimension. In the preparative process, UV‐triggered fraction collection was used in the first dimension while UV and MS‐triggered collection were used in the second dimension for reasons of sensitivity and complementarity. Two pure compounds and nine fractions were obtained in the first dimension. Then two representative fractions were further purified in the second dimension and six pure compounds were obtained. The results demonstrated that this procedure is an effective approach for the preparative isolation and purification of alkaloids from Corydalis yanhusuo. Based on the different pH values of the mobile phase in this method, it is also suitable for the preparative isolation and purification of other compounds from TCMs which are sensitive to the pH of the solutions. Moreover, this method will be a promising tool for the purification of low content compounds from natural products.     

修正高斯模型在制备液相色谱收集区间优化中的应用

近年来制备液相色谱得到了越来越广泛的应用。制备液相色谱操作条件的优化对提高其效率及节约成本非常重要。对制备高效液相色谱而言,其样品收集区间的确定及优化是其操作条件优化的重要步骤。该文以修正高斯模型(EMG模型)为理论基础,编写了一个小软件,可有效地帮助用户确定合理的样品收集区间。此软件对制备液相色谱实际应用有积极的指导及参考意义。     

Simultaneous isolation of artemisinin and its precursors from Artemisia annua L. by preparative RP-HPLC

It is still a major challenge to simultaneously isolate artemisinin and its precursors, especially dihydroartemisinic acid and artemisinic acid, from herbal Artemisia annua. A rapid, economical and automatical chromatographic separation process to isolate and purify artemisinin, dihydroartemisinic acid and artemisinic acid at the same time on a preparative scale was developed. The procedure included solvent extraction of ground Artemisia annua leaves by refluxing and purification of crude extract by preparative reverse-phase high-performance liquid chromatography (RP-HPLC). Fractions containing artemisinin and its precursors were collected and identified by gas chromatography and mass spectrometry. High purity of artemisinin, dihydroartemisinic acid and artemisinic acid was obtained by preparative HPLC with a C(18) column and 60% acetonitrile in water as the mobile phase. The techniques described here are useful tools for the preparative-scale isolation of artemisinin and its precursors in a fast, cost-effective and environmental friendly manner.     

Preparative HPLC. Part 1: A comparison of three types of equipment for the purification of steroids

Two commercial preparative liquid chromatographs have been evaluated for gram-scale purification of steroid esters. The Jobin-Yvon and Waters chromatographs both allow fast separations. Neither system has a high intrinsic column efficiency, but the resolving power of the Waters system can be increased by the use of recycle. A laboratory-assembled preparative liquid chromatograph is described which is economical both in construction and operation, versatile, and considerably more efficient than the two commercial alternatives for single runs on up to a gram scale.     

Preparative separation of isoquinoline alkaloids from Corydalis impatiens using middle chromatogram isolated gel column coupled with positively charged reversed‐phase liquid chromatography

Positively charged reversed‐phase liquid chromatography was employed for the efficient preparative separation of isoquinoline alkaloids from Corydalis impatiens. Ten commercially available columns were compared for isoquinoline alkaloids analysis. While tailing, overloading, lower resolution, and buffer salts limited the application in purification of isoquinoline compounds of many of these columns, one positively charged reversed‐phase C18 column (XCharge C18) overcame these drawbacks, allowing for favorable separation resolution, even when loading isoquinoline compounds on a larger, preparative scale. The general separation process is as follows. First, isoquinoline alkaloids are enriched with Corydalis impatiens extract via a middle chromatogram isolated gel column. After column selection, separation is performed on an XCharge C18 analytical column, from which two evident chromatographic peaks are readily obtained. Finally, two isoquinoline alkaloids (protopine and corydamine) are selectively purified on the XCharge C18 preparative column. These results demonstrate that a middle chromatogram isolated gel column coupled with positively charged reversed‐phase liquid chromatography is effective for the preparative separation of isoquinoline alkaloids from Corydalis impatiens.     

Purification of flavonoids from licorice using an off‐line preparative two‐dimensional normal‐phase liquid chromatography/reversed‐phase liquid chromatography method

An orthogonal (71.9%) off‐line preparative two‐dimensional normal‐phase liquid chromatography/reversed‐phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self‐made Click TE‐Cys (60 μm) solid‐phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE‐Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co‐eluted in the first dimension were selected for further purification using reversed‐phase liquid chromatography. Multiple compounds could be isolated from one normal‐phase fraction and some compounds with bad resolution in one‐dimensional liquid chromatography could be prepared in this two‐dimensional system owing to the orthogonal separation. Moreover, this two‐dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off‐line two‐dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.     

酪蛋白多肽的制备和色谱分离方法

为了得到低成本的多肽,本文利用胰蛋白酶对酪蛋白进行了充分的酶解。采用分析级反相高效液相色谱-电喷雾质谱联用技术(RP-HPLC/ESI-MS)分析了酶解产物各组分的组成,并通过改变流动相的梯度洗脱程序,优化了分析级色谱条件以充分分离相对含量较高的多肽组分;将优化的分析级色谱条件直接放大到制备级RP-HPLC中,在程序控制下通过紫外吸收信号结合ESI-MS信号共同引导实现了多肽的全自动化分离和收集。整个过程方便快捷,经过这样一个单一的分离步骤,得到了多个纯度较高的多肽。除此之外,本文还考察了流动相的酸碱性、柱上样量等因素对该体系制备级分离的影响,并对一次分离中分辨率不好的亲水性多肽混合物进行了二次分离,得到了多个新的多肽。本文建立的多肽制备方法为多肽和多肽材料的广泛应用提供了一种选择。     

Preparative isolation of flavonoid glycosides from Sphaerophysa salsula using hydrophilic interaction solid‐phase extraction coupled with two‐dimensional preparative liquid chromatography

An offline preparative two‐dimensional reversed‐phase liquid chromatography/hydrophilic interaction liquid chromatography coupled with hydrophilic interaction solid‐phase extraction method was developed for the preparative isolation of flavonoid glycosides from a crude sample of Sphaerophysa salsula . First, the non‐flavonoids were removed using an XAmide solid‐phase extraction cartridge. Based on the separation results of three different chromatographic stationary phases, the first‐dimensional preparation was performed on an XAqua C18 prep column, and 15 fractions were obtained from the 5.2 g target sample. Then, three representative fractions were selected for additional purification on an XAmide preparative column to further isolate the flavonoid glycosides. In all, eight flavonoid glycosides were isolated in purities over 97%. The results demonstrated that the two‐dimensional liquid chromatography method used in this study was effective for the preparative separation of flavonoid glycosides from Sphaerophysa salsula . Additionally, this method showed great potential for the separation of flavonoid glycosides from other plant materials.     

Trends in countercurrent chromatography

Since the early 1970s countercurrent chromatography has achieved a remarkable advance and is currently yielding rapid and efficient chromatographic separations that are comparable with those obtained with preparative high-performance liquid chromatography. The method further provides unique applications such as partition with polymer phase systems, foam separation and liquid—liquid dual countercurrent chromatography.     

Preparative isolation of oligodeoxynucleotides

Summary DNA can be degradated on a preparative scale to mixtures of oligonucleotides by various chemical methods. The resulting highly complex oligonucleotide mixture can be almost completely separated by liquid chromatography. The separation procedures are demonstrated by the isolation of pyrimidine oligonucleotides from a partial hydrolysate of herring sperm DNA. The partial hydrolysate is fractionated into oligonucleotide mixtures of defined compositions by a separation route in which ion exchangers are used at different pH-values. From the resulting mixtures of sequence isomers pyrimidine oligonucleotides of defined sequences are obtained by ion exchange and/or reversed phase HPLC. Oligonucleotides which can not be isolated by this separation route are obtained from the preseparated partial hydrolysate by template chromatography using the specificity of the base-pairing mechanism. Purity and sequence of the isolated oligonucleotides are determined by the “fingerprint” method. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

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.     

Separation of structurally similar nocathiacin analogues by reversed phase chromatography

The complete separation of structurally similar compounds has been a challenge due mainly to their similarity on physical and chemical properties. In the present study, a simple and effective chromatographic method to separate and purify nocathiacin acid from its structural analogue nocathiacin I was developed. After evaluating mobile phase compositions on the retention characteristics by reversed phase high-performance liquid chromatography (HPLC), the elution order of nocathiacin I and nocathiacin acid was completely reversed, and the resolution value between the two analogues was improved, by varying pH value and ionic strength, to greater than 10 from merged peaks under initial conditions. In addition, a preparative isolation of nocathiacin acid was performed by reversed phase column chromatography under the guidance of the HPLC study. This chromatographic method resulted in an efficient process to obtain pure nocathiacin acid with a recovery rate of 83%. The present approach offers a new methodology for the separation of structurally closely related secondary metabolites.     

High-Pressure Liquid Chromatography (HPLC) of Proteins [New Analytical Methods (29)]

The application of high-pressure liquid chromatography (HPLC) to proteins has undergone a dramatic development in recent years. Nowadays its many variants expand the repertoire of high-performance analysis methods available to the protein chemist, which, until now, have been dominated by electrophoretic techniques. The advent of gene technology has resulted in a renaissance of protein chemistry. The new analytical and preparative problems that have thereby emerged are often ideally solved by HPLC methods. HPLC has long since ceased to be solely a laboratory technique; HPLC systems are now being developed for the separation of proteins–particularly those of great pharmaceutical interest – on a 100-g scale. The range of applications of analytical and preparative HPLC will be illustrated by two examples of pharmaceutical importance—insulin and interleukin 2.     

Identification of very long chain fatty acids by atmospheric pressure chemical ionization liquid chromatography‐mass spectroscopy from green alga Chlorella kessleri

A method is described for the enrichment of very long chain fatty acids (VLCFAs) from total fatty acids of heterotrophically cultivated green freshwater alga Chlorella kessleri and their identification as picolinyl esters by means of liquid chromatography‐mass spectrometry with atmospheric pressure chemical ionization (LC‐MS with APCI). The method is based on the use of preparative reversed phase HPLC of hundred‐milligram amounts and their subsequent identification by microbore APCI LC‐MS. A combination of these two techniques was used to identify unusual VLCFAs up to C₄₇, both saturated and monounsaturated, with two positional isomers (ω‐9 and ω‐26).     

Direct analytical and preparative resolution of enantiomers using albumin adsorbed to silica as a stationary phase

A rapid and simple method for the preparation of high-performance liquid chromatography columns for chiral separations is described. The stationary phase is prepared by adsorbing bovine serum albumin on silica. Both analytical and preparative applications are described. A polarimeter was used as a detector to determine the enantiomer elution orders.     

The Use of Polystyrene Gels in Preparative Recycle-HPLC for the Separation of Structurally Related Molecules

Abstract

This paper deals with the use of polystyrene gels in high performance liquid chromatography for preparative separations of small molecules with very similar structures. The preparative chromatograph, equipped with a recycle device and made in our laboratory, is described. The column set, consisted of three columns packed with low porosity polystyrene gel. The mobile phase was diisopropylether. Three particle sizes (10μ, 20μ, 50μ) were studied for improving the preparative performance. We checked the very high efficiency of our recycling system versus sample load. High sample loadings (up to 100 grams) can be injected when the separation does not require a large number of plates but typical sample loads are 10–20 grams for high performance separations. Some examples of separation of diastereoisomers, configurational isomers or related structure molecules are given. The advantages of our preparative system are discussed.     

Preparation of five high‐purity iridoid glycosides from Gardenia jasminoides Eills by molecularly imprinted solid‐phase extraction integrated with preparative liquid chromatography

Five iridoid glycosides were prepared using molecularly imprinted solid‐phase extraction combined with preparative high‐performance liquid chromatography. Hydrophilic molecularly imprinted polymers were synthesized using α‐1‐allyl‐2‐N‐acetyl glucosamine, which introduced an abundance of hydrophilic groups into the polymers. Using molecularly imprinted solid‐phase extraction as the sample pretreatment procedure, five iridoid glycosides, gardenoside, geniposide, shanzhiside, geniposidic acid, and genipin‐1‐O‐gentiobioside, were selectively enriched from Gardenia fructus extracts. Preparative high‐performance liquid chromatography then provided iridoid glycosides with a purity >98%. The structures were elucidated by using nuclear magnetic resonance spectroscopy, optical rotation and melting point measurements, and mass spectrometry. The results demonstrate that molecularly imprinted solid‐phase extraction combined with preparative high‐performance liquid chromatography was an efficient, rapid, and economical method for the preparation of bioactive compounds from natural products.     

Application of an efficient strategy based on liquid–liquid extraction,high‐speed counter‐current chromatography,and preparative HPLC for the rapid enrichment,separation, and purification of four anthraquinones from Rheum tanguticum

This study presents an efficient strategy based on liquid–liquid extraction, high‐speed counter‐current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid–liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe‐emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high‐speed counter‐current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe‐emodin, physcione, and chrysophanol.     

A Low Cost Gram Quantity Preparative Reverse Phase Chromatography System

Abstract

The preparation of a low cost reverse phase preparative liquid chromatography system is described. The described system is capable of providing gram quantity scale-up from analytical reverse phase hplc systems. Load capacity is in the two gram range.     

HPLC Purification of Solid-Phase Generated Synthetic Bombesin

Abstract

A scheme based on ion-exchange and reverse-phase high pressure liquid chromatography has been utilized for the semi-preparative and preparative purification of the solid phase generated model peptide bombesin. The final product showed a purity ≥ 99% in analytical reverse-phase high pressure liquid chromatography and was identical to authentic bombesin as demonstrated by different physico-chemical and biological criteria. The results are discussed and compared to those obtained using countercurrent chromatography.