Liquid chromatography preparative-scale

Preparative liquid chromatography. Any scale of operation in which the objective is the collection of sample components for subsequent identification or use. Preparative LC may involve submilligram or multigram quantities. 

HPLC separations are one of the most important fields in the preparative resolution of enantiomers. The instrumentation improvements and the increasing choice of commercially available chiral stationary phases (CSPs) are some of the main reasons for the present significance of chromatographic resolutions at large-scale by HPLC. Proof of this interest can be seen in several reviews, and many chapters have in the past few years dealt with preparative applications of HPLC in the resolution of chiral compounds [19-23]. However, liquid chromatography has the attribute of being a batch technique and therefore is not totally convenient for production-scale, where continuous techniques are preferred by far. 

Racemic mixtures of sulfoxides have often been separated completely or partially into the enantiomers. Various resolution techniques have been used, but the most important method has been via diastereomeric salt formation. Recently, resolution via complex formation between sulfoxides and homochiral compounds has been demonstrated and will likely prove of increasing importance as a method of separating enantiomers. Preparative liquid chromatography on chiral columns may also prove increasingly important it already is very useful on an analytical scale for the determination of enantiomeric purity. 

The last several years have seen an enormous growth in the number and use of chiral stationary phases in liquid chromatography [742,780-791]. Some problems with the gas chromatographic approach are that the analyte must be volatile to be analyzed and larger-scale preparative separations are frequently difficult. For entropic reasons relatively high temperatures tend to minimize the stability differences between the diastereomeric complexes and racemization of the stationary phase over time may also occur. The upper temperature limit for phases such as Chirasil-Val is about 230 C and is established by the rate of racemization of the chiral centers and not by column bleed. Liquid chromatography should be s ior in the above... 

The purpose of preparative-scale liquid chromatography is the isolation of materials conforming to a specified purity in cUBOunts that depend on the intended use of the product [8,570-572]. Possible uses Include the isolation of materials for structural elucidation, for biological or sensory evaluation, for organic synthesis or commercial applications. The scale of the... 

Colin, H., Large-scale high-performance preparative liquid chromatography, in Preparative and Production Scale Chromatography, Ganetsos, G. and Barker, P. E. Eds., Marcel Dekker, New York, 1988, 11. 

Nicoud R. M., Fuchs G., Adam P., Baftly M., Kiisters E., Antia F., Reuille R., Schmid E. (1993) Preparative Scale Enantioseparation of a Chiral Epoxide Comparison of Liquid Chromatography and Simulated Moving Bed Adsorption Technology, Chirality 5 267-271. 

These incubations are often carried out at 37 °C for 1-2 h. At different time points, 20-200 /aL of incubation mixture is withdrawn from each incubation and mixed with equal volume of ice-cold acetonitrile by vortexing. For preparation of acyl glucuronide, ice-cold acetonitrile containing 1% of formic acid is used to minimize acyl-migration [3,14]. After centrifugation at 13 000 rpm for 5-15 min, the supernatant (10-30 /aU) is analyzed by high-performance liquid chromatography (HPUC)-UV-MS. The metabolite of interest is identified based on HPLC retention time, UV spectrum and MS/MS data. Conversion yield is estimated based on UV absorption peak areas. A suitable in vitro enzyme system for scale-up is then... 

Subramanian, G. (ed.) Preparative and Process-Scale Liquid Chromatography (Ellis Horwood, 1991) Subramanian, G. (ed.) Process-Scale Liquid Chromatography (VCH Verlagsgesellschaft, 1995)... 

A light beam is refracted to different extents by different compounds. This mechanism is used for refractive index detection. This detector is not sensitive and the selectivity differences are negligible for homologous compounds, but any solvent with a different refractive index to the analyte can be used as the eluent. This detector is mainly applied to size-exclusion and preparative-scale liquid chromatography. 

Like dissolves like is the basic concept for the selection of solvents in the eluent for liquid chromatography. Controlling the solubility of analytes is the key to success. If the selected solvent or mixture of solvents does not interfere with detection, it is a good eluent. The selection of a suitable solvent for low-wavelength absorption detection and post-column derivatization detection is important to obtain highly sensitive detection. The selection of a volatile solvent is the key for preparative-scale liquid chromatography and for mass spectro-metric detection. 

The synthesis of 6-hydroxy fluvastatin with M. rammaniana DSM 62752 gave high conversion (>95 %) in shake flask culture on 400 mL scale with 0.1 g L of fluvastatin as well as on 22 L scale in a Wave bioreactor-fed batch process at a final substrate concentration of 0.4 g L Instead of the partial purification by a second solid-phase extraction described above, 6-hydroxy fluvastatin can be obtained in high purity ( 95 %) by, for example, preparative medium-pressure liquid chromatography (MPLC) on RP18 silica gel. ... 

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