Separation and Scale-Up of an Achiral Compound Utilizing the RegisCell® CSP

Eric E. Pullen, Andrew G. Geyer, and Vinay M. Edwin, Regis Technologies, Inc.

Although supercritical fluid chromatography (SFC) is generally regarded as a technique to separate enantiomers, it has also been proven in many laboratories as a fast approach for the purification of impurities in achiral samples.

Figure 1

A proprietary active pharmaceutical ingredient (API) was examined by both RP-HPLC and SFC methodology for the elimination of a ~0.8% impurity. The compound of interest and the impurity have a M.W. > 350 daltons and differ structurally by only an acetamide versus a formamide group.

The best RP-HPLC method found for the separation was isocratic with a high percentage of an R-OH solvent with H₂0 on a C₁₈ column.

Figure 2

A method utilizing 35% MeOH in CO₂ on a RegisCell® column was developed for SFC. Figure 1 illustrates the analytical separation and subsequent loading calculations.

Experimentally Determined Production Rates

Single Column:

25 cm X 4.6 mm – 190 mg/h

25 cm X 21.1 mm – 4.6 gm/h

Serially Coupled Columns:

Two - 25 cm X 4.6 mm – Not performed

Two - 25 cm X 21.1 mm – 16 gm/h

Conclusions

As shown, the ability to separate the desired compound from the main impurity would be extremely time consuming and costly by RP-HPLC on a large scale. However, by using SFC the gains in efficiency are obvious and significant with this sample. Extrapolation of the experimentally derived data to two 25 cm X 50 mm columns would result in a production rate of over 90 grams/h.

Regis Technologies, Inc.

8210 Austin Ave, Morton Grove, IL 60053

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Website: www.registech.com