Loop Recycling Chromatography

The main advantage of CLRC is the possibility of isolating even components of low selectivity with good purity and yield, as no fractions with insufficient purities are withdrawn from the system. A second interesting aspect is that the consumption of mobile phase is not increased by this concept. During the closed-loop operation no eluent is consumed as the complete mobile phase is circulated within the system. Fresh eluent has to be introduced only during the intervals when the original feed is injected and the fractions are collected. 

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J. Dingenen and J. N. Kinkel, Preparative chromatographic resolution of racemates on chiral stationary phases on laboratory and production scales by closed-loop recycling chromatography , J. Chromatogr. 666 627 -650 (1994). 

Closed-loop recycling chromatography (reviewed by Dingenen and Kinkel 422)) may be necessary for separations of compt)unds with low enantioselectivity. 

The critical point in closed-loop recycling chromatography is the increase in axial dispersion due to the additional hold-up volume generated by the pump head and... 

Fig. 5.9 Closed-loop recycling chromatography with peak shaving.

Fig. 5.10 Development of concentrations during closed loop recycling chromatography operation with peak shaving.

Table 6. Selected examples of preparative enantioseparation of chiral drugs, drug candidates and drug intermediates using closed-loop recycling chromatography (CLRC)...

Figure 5.5 Closed-loop recycling chromatography with peak shaving. A corresponding chromatogram is shown in Figure 5.6.

Figure 7.17 Scale-up strategy for closed loop recycling chromatography.

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