Batch chromatography

The following examples illustrate a few effects encountered in model validation based on our research (Epping, 2005 Jupke, 2004). All process simulations are based on the transport-dispersive model. Model equations were solved by the gPROMS Software (PS Enterprise, UK) using the OCFE method (Section 6.4). 

EMD53986 racemic mixture using single- and multicomponent isotherms (exp., experimental  

The validity of the transport-dispersive model was further successfully confirmed by experiments with other chromatographic systems such as Trbger s base (Mihlbachler et al., 2001 Jupke, 2004), the WMK-Keton (Epping, 2005), and fructose-glucose (Jupke, 2004). 

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There are many advantages of the SMB technology compared to batch preparative chromatography. The process is continuous and the solvent requirement is minimal compared to batch. In SMB, the whole stationary phase is used for the separation while in batch chromatography only a small part of the column is involved in the separation. This allows optimization of productivity with respect to the stationary phase. 

Column efficiency (number of theoretical plates) As in batch chromatography, one needs to determine the efficiency of the column in order to evaluate the dispersion of the fronts due to hydrodynamics dispersion or kinetics limitations. The relationship of N proportional to L can be expressed in terms of the equation for height equivalent to a theoretical plate (HETP) as ... 

Batch carbon dioxide foaming, 24 21 Batch chromatography, for enantiomeric purification of pharmaceutical intermediate, l 685t Batch compartment dryers, 9 118-119 Batch compression filters, mechanical, 11 370-373... 

On the other hand, SMB requires strict process control and is less versatile than normal elution chromatography. In that sense, SMB should be viewed predominately as a very powerful tool for production plants, while batch chromatography with its higher flexibility is equally well suited for development purposes. The fact that efficient simulation software is needed to set up an SMB, while an empirical approach is often sufficient for success in batch chromatography points in the same direction. 

LARGE-SCALE ELUTION (CYCLIC BATCH) CHROMATOGRAPHY... 

Batch chromatography can be used to analyse many samples at once, increasing the speed of analysis, and can be automated. 

In the second example the separation of two optical isomers by batch chromatography using box car injections demonstrates one approach to purification by chiral chromatography. 

The absorption spectra of the fractions obtained during the purification of the PSI particles are shown in Fig la. Both the sonicate and the original 40,000 xg supernatant showed a major peak at 620 nm due to soluble phycobiliproteins, which can be completely removed by batch chromatography on DE AE-cellulose. Thus, the A620/A676 ratio, which compares the absorption maxima of blue pigments to that of chlorophyll was 2.73 in the sonicate, 3.81 in the 40,000 xg supernatant, and only 0.27 in the DE-52 eluate. 

The chromatographic process we have defined is also known as zonal or batch chromatography because the sample is applied to the system all at once in one narrow zone. By contrast, the sample can be applied continuously during a run this process is called frontal analysis, and it will not be discussed further because of its limited use. 

Some work has been done to perform the separation of fatty acids. The first results were published by Szepy52 and were associated with the separation of C16 to C22 methyl esters. An interesting patent has been granted to Pronova53 which associates classical (batch) chromatography with an SMB with two inlets to obtain pure EPA(C2o) and pure DHA(C22) from... 

The SMB is basically a binary separator that presents three main advantages over batch chromatography. 

It enables us to maximize productivity. The value of SMBs with respect to batch chromatography is maximized for low selectivity problems or low efficiency systems. 

However, SMB utilization requires a strict procedure, an efficient simulation software and is less versatile than batch chromatography. In fact these two modes are more complementary than competitive SMB is really a production tool, when batch chromatography, thanks to its flexibility, has some interesting advantages during the first stages of development. 

Conventional batch chromatography with CSPs and column dimensions that allow injection of reasonable amounts of racemate (reviewed by Francotte [96,420,4211) is still a very favourable technique in the early stage of drug development. 

Automation allows batch chromatography to be run as a continuous process. Multiple injections using a separate pump and fraction collection provide an opportunity for continuous unattended operation. In iso-cratic separations, sample injection is often made before previously injected product elutes from the column, thus reducing cycle time and solvent consumption. Continuous and automated processes are always used with smaller columns and lower amounts of expensive enantioselective stationary phases. One of the future goals for modern PHPLC optimization would be the creation of software that would allow computer simulation modeling of nonlinear effects in preparative chromatography. 

Gao W. and Engell S., Iterative set-point optimization of batch chromatography , Comput Chem Eng 29(6y.l40l-l409,2005. 

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