Modeling the performance of pilot-scale countercurrent chromatography: scale-up predictions and experimental verification of erythromycin separation

Centrifugal partition chromatography in a biorefinery context: Separation of monosaccharides from hydrolysed sugar beet pulp

A critical step in the bioprocessing of sustainable biomass feedstocks, such as sugar beet pulp (SBP), is the isolation of the component sugars from the hydrolysed polysaccharides. This facilitates their subsequent conversion into higher value chemicals and pharmaceutical intermediates. Separation methodologies such as centrifugal partition chromatography (CPC) offer an alternative to traditional resin-based chromatographic techniques for multicomponent sugar separations. Highly polar two-phase systems containing ethanol and aqueous ammonium sulphate are examined here for the separation of monosaccharides present in hydrolysed SBP pectin: l-rhamnose, l-arabinose, d-galactose and d-galacturonic acid. Dimethyl sulfoxide (DMSO) was selected as an effective phase system modifier improving monosaccharide separation. The best phase system identified was ethanol:DMSO:aqueous ammonium sulphate (300gL(-1)) (0.8:0.1:1.8, v:v:v) which enabled separation of the SBP monosaccharides by CPC (200mL column) in ascending mode (upper phase as mobile phase) with a mobile phase flow rate of 8mLmin(-1). A mixture containing all four monosaccharides (1.08g total sugars) in the proportions found in hydrolysed SBP was separated into three main fractions; a pure l-rhamnose fraction (>90%), a mixed l-arabinose/d-galactose fraction and a pure d-galacturonic acid fraction (>90%). The separation took less than 2h demonstrating that CPC is a promising technique for the separation of these sugars with potential for application within an integrated, whole crop biorefinery.

A priori selection of the mobile and stationary phase in centrifugal partition chromatography and counter-current chromatography

The selection of the mobile and the stationary phase in support-free liquid-liquid chromatography (centrifugal partition chromatography and counter-current chromatography) is equivalent to a selection of a biphasic liquid system and its global composition. There is an immense number of choices of biphasic liquid systems. On one hand what makes this technique extremely versatile, on the other hand turns the selection of the appropriate system for a particular separation problem into a challenging and demanding task. In this work a systematic procedure for the selection of biphasic liquid systems for preparative scale separations is presented. The procedure is adaptable to the production scale requirements including production cost and safety. The experimental effort of different stages of the selection procedure is minimized by using a fully predictive method, the conductor-like screening model for real solvents (COSMO-RS). The COSMO-RS is used to assess properties relevant for the selection of a biphasic liquid system, such as the solute solubility and the partition coefficient.

Separation of natural products by countercurrent chromatography

Countercurrent Chromatography (CCC) provides the natural product chemist with a high-resolution separatory method, which is uniquely applicable to sensitive (unstable) compounds and which allows virtually quantitative recovery of the load sample. Different instruments use different means of retaining a stationary liquid phase. The solvent system (SS) can be chosen to optimize the separatory power and the number of systems available is limitless. Several examples are provided to illustrate the power of the method and to guide the chemist in choice of an appropriate SS.

Countercurrent separation of natural products

An assessment of the technology and method development in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CS), is provided. More than six decades of CS theory and applications are critically reviewed and developed into a practical guide to CS for natural products research. The necessary theoretical foundation is given for better use of CS in the separation of biological molecules of any size, small to large, and from any matrix, simple to complex. The three operational fundamentals of CS--instrumentation, biphasic solvent systems, and theory--are covered in a prismatic fashion. The goal of this review is to provide the necessary background and references for an up-to-date perspective of CS and to point out its potential for the natural products scientist for applications in natural products chemistry, metabolome, and proteome research involving organisms from terrestrial and marine sources.

Recent progress on the industrial scale-up of counter-current chromatography

The pharmaceutical industries are looking for rapid methods of purification and predictable scale-up for their drug development process that will cut their costs and enable them to reduce the time to market. In this paper, recent progress is reviewed in the development and demonstration of two types of industrial scale centrifugal liquid-liquid chromatography: hydrostatic and hydrodynamic. Industrial scale hydrostatic processes by Partus Technologies and Armen Instrument are just emerging. Results demonstrating scalability are presented for hydrodynamic processes by Dynamic Extractions. The review concludes that the time is now right, with this appropriate commercial support, for high performance counter-current chromatography to emerge as a major enabling technology for industry.

Preparative isolation and purification of atractylon and atractylenolide III from the Chinese medicinal plantAtractylodes macrocephala by high-speed counter-current chromatography

The medicinal plant Atractylodes macrocephala (Baizhu in Chinese) has been widely used in traditional Chinese medicine for energy and stomach complaints, treatment of dyspepsia and anorexia, anti-inflammation, anticancer and for increasing assimilation. A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of two main bioactive components, namely, atractylon and atractylenolide III from A. macrocephala by using light petroleum (60-90 degrees C)-ethyl acetate-ethanol-water (4:1:4:1 v/v) as the two-phase solvent system in dual-mode elution. Compared with the separation using the normal-mode elution, the dual-mode HSCCC can be achieved with shorter elution time. Atractylenolide III (32.1 mg) at 99.0% purity and 319.6 mg atractylon at 97.8% purity could be obtained from 1000 mg crude sample in a single run. The recoveries of atractylenolide III and atractylon were 95.4 and 92.6%, respectively.

How to achieve rapid separations in counter-current chromatography

A new generation of high performance coil planet centrifuges is now making it possible to realize the enormous potential of liquid-liquid partition chromatography for the rapid and predictable scale up of separation processes. This paper uses a separation of flavonoids to demonstrate how rapid fractionations can be obtained at high flow rates with limited loss of resolution and with significant increase in throughput. Furthermore, it is shown that chromatograms at various flows can be modeled so that optimum conditions can be rapidly assessed.

Antibiotic purification from fermentation broths by counter-current chromatography: analysis of product purity and yield trade-offs

Counter-current chromatography (CCC) is a low pressure, liquid-liquid chromatographic technique which has proven to be a powerful purification tool for the high-resolution fractionation of a variety of active pharmaceutical compounds. The successful integration of CCC into either existing or new manufacturing processes requires the predictable purification of target compounds from crude, fermentation-derived, feed streams. This work examines the feasibility of CCC for the purification of fermentation-derived erythromycin A (EA) from its structurally and chemically similar analogues. At the laboratory scale, the effect of feed pre-treatment using either clarified, forward extracted (butyl acetate) or back extracted broth on EA separation was investigated. This defined the degree of impurity removal required, i.e. back extracted broth, to ensure a reproducible elution profile of EA during CCC. Optimisation and scale-up of the separation studied the effects of mobile phase flow (2-40 ml.min(-1)) and solute loading (0.1-10 g) on the attainable EA purity and yield. The results in all cases demonstrated a high attainable EA purity (>97% w/w) with throughputs up to 0.33 kg.day(-1). Secondly, a predictive scale-up model was applied demonstrating, that from knowledge of the solute distribution ratio of EA (K(EA)) at the laboratory scale, the EA elution time at the pilot scale could be predicted to within 3-10%, depending upon the solute injection volume. In addition, this study has evaluated a "fractionation diagram" approach to visually determine the effects of key operational variables on separation performance. This resulted in accurate fraction cut-point determination for a required degree of product purity and yield. Overall, the results show CCC to be a predictable and scaleable separation technique capable of handling real feed streams.